Article

Spatial Scaling in Ecology

January 1989
Functional Ecology 3:385-397

January 1989
3:385-397

Authors:

Oregon State University

Considers the effects of scale using various examples and ways of dealing with scale. Outlines the definition of dependence on objectives and on organisations, and the domains of scale. Discusses the development of science in ecology and the development of a scaling theory which could generate testable hypotheses. -S.J.Yates

Exploring benthic habitat assessments on coral reefs: a comparison of direct field measurements versus remote sensing

Article

Full-text available

Feb 2024
CORAL REEFS

Coral reefs are spatially variable ecosystems that form biogenic structures ranging in size from 10 to 1000s of meters. Their changes in response to anthropogenic stress are occurring across increasingly broad scales, yet our ability to detect, understand and respond to these changes at relevant scales is limited. Traditional in-water observation-based coral reef ecology and remote sensing-based methods both offer valuable insights into benthic change, but their relative scalability and use to-date must be understood to inform optimal future research approaches. We conducted a systematic literature review comparing the approaches used to quantify benthic habitat, through traditional in-water ecological studies and remote sensing studies, with respect to: (a) their geographic distribution, (b) reef zone selection, and c) their focal questions. Among the 199 studies reviewed, traditional ecological studies primarily concentrated on community composition (89%), using high-detail direct measurements, especially from the reef slope (80%). By contrast, remote sensing studies provided spatially explicit datasets at coarser spatial and thematic resolutions, with a predominant focus on benthic mapping (72%) across entire reef systems. Only 3% of studies integrated both approaches, combining comprehensive in-situ observations with broadscale remote sensing. As anthropogenic stressors continue to increase in scale, bridging these scientific disciplines offers a promising way to upscale observations to entire reef-scape scales. We identify steps to harness the strengths of both fields and integrate multiple tools at various levels of resolution and scale. Such bridging approaches offer a way forward in understanding and managing coral reef functioning in the Anthropocene.

GEE_xtract: High-quality remote sensing data preparation and extraction for multiple spatio-temporal ecological scaling

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May 2024
ECOL INFORM

Environmental sensing via Earth Observation Satellites (EOS) is critically important for understanding Earth’ biosphere. The last decade witnessed a “Klondike Gold Rush” era for ecological research given a growing multidisciplinary interest in EOS. Presently, the combination of repositories of remotely sensed big data, with cloud infrastructures granting exceptional analytical power, may now mark the emergence of a new paradigm in understanding spatio-temporal dynamics of ecological systems, by allowing appropriate scaling of environmental data to ecological phenomena at an unprecedented level. However, while some efforts have been made to combine remotely sensed data with (near) ground ecological observations, virtually no study has focused on multiple spatial and temporal scales over long time series, and on integrating different EOS sensors. Furthermore, there is still a lack of applications offering flexible approaches to deal with the scaling limits of multiple sensors, while ensuring high-quality data extraction at high resolution. We present GEE_xtract, an original EOS-based (Sentinel-2, Landsat, and MODIS) code operational within Google Earth Engine (GEE) to allow for straightforward preparation and extraction of remote sensing data matching the multiple spatio-temporal scales at which ecological processes occur. The GEE_xtract code consists of three main customisable operations: (1) time series imageries filtering and calibration; (2) calculation of comparable metrics across EOS sensors; (3) scaling of spatio-temporal remote sensing time series data from ground-based data. We illustrate the value of GEE_xtract with a complex case concerning the seasonal distribution of a threatened elusive bird and highlight its broad application to a myriad of ecological phenomena. Being user-friendly designed and implemented in a widely used cloud platform (GEE), we believe our approach provides a major contribution to effectively extracting high-quality data that can be quickly computed for metrics time series, converted at any scale, and extracted from ground information. Additionally, the framework was prepared to facilitate comparative research initiatives and data-fusion approaches in ecological research.

Assessing the functional vulnerability of woody plant communities within a large scale tropical rainforest dynamics plot

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Apr 2024

Introduction Tropical forests are characterized by intricate mosaics of species-rich and structurally complex forest communities. Evaluating the functional vulnerability of distinct community patches is of significant importance in establishing conservation priorities within tropical forests. However, previous assessments of functional vulnerability in tropical forests have often focused solely on isolated factors or individual disturbance events, with limited consideration for a broad spectrum of disturbances and the responses of diverse species. Methods We assessed the functional vulnerability of woody plant communities in a 60-ha dynamic plot within a tropical montane rainforest by conducting in silico simulations of a wide range disturbances. These simulations combined plant functional traits and community properties, including the distribution of functional redundancy across the entire trait space, the distribution of abundance across species, and the relationship between species trait distinctiveness and species abundance. We also investigated the spatial distribution patterns of functional vulnerability and their scale effects, and employed a spatial autoregressive model to examine the relationships between both biotic and abiotic factors and functional vulnerability at different scales. Results The functional vulnerability of tropical montane rainforest woody plant communities was generally high (the functional vulnerability of observed communities was very close to that of the most vulnerable virtual community, with a value of 72.41% on average at the 20m×20m quadrat scale), and they exhibited significant spatial heterogeneity. Functional vulnerability decreased with increasing spatial scale and the influence of both biotic and abiotic factors on functional vulnerability was regulated by spatial scale, with soil properties playing a dominant role. Discussion Our study provides new specific insights into the comprehensive assessment of functional vulnerability in the tropical rainforest. We highlighted that functional vulnerabilities of woody plant communities and their sensitivity to environmental factors varied significantly within and across spatial scales in the tropical rainforest landscape. Preserving and maintaining the functionality of tropical ecosystems should take into consideration the variations in functional vulnerability among different plant communities and their sensitivity to environmental factors.

Integrating Landscape Ecology in Urban Green Infrastructure Planning: A Multi-scale Approach for Sustainable Development

Article

Feb 2024

In response to the growing global recognition of the need to achieve sustainable development, significant efforts are underway to actively integrate nature into the urban environment by implementing green infrastructure. However, due to rapid urban growth, there is a need for novel approaches that integrate ecological knowledge and methods into urban green infrastructure design and development. Traditionally, the planning of green in frastructures in large metropolises has primarily approached from a unique city scale perspective. Here, we advocate for a multi-scale approach, encompassing both spatial and temporal dimensions. This is because by considering space, time, and scale, it is possible to identify relevant elements and constraints at each level and integrate them in an overall solution. This paper combines methodologies and concepts derived from the fundamentals of landscape ecology and proposes their integration into the planning of functional green infrastructures within an urban context. We explore distinct strategies to integrate nature into large cities through three perspectives: urbanism, landscaping, and ecology. The approach used assumes the necessity of a multi-scale framework to establish an integrated and sustainable green system, exemplified by the case study of the city of Madrid (Spain). Considerable progress has been made in the planning of a green belt within Madrid city. However, this initiative has focused primarily on a large-scale, leading to a minimal impact on the city core. To address this limitation, the proposed solution employs a multi-scale approach. By developing a connected network, we aim to provide a comprehensive plan for the integration of green infrastructure throughout the whole urban area.

Dynamic, multi-scale analyses indicate site- and landscape-level forest cover drive Yellow-billed and Black-billed Cuckoo interannual turnover

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Feb 2024

Studies of habitat use in breeding birds often assume species have relatively stable breeding distributions. Some species, however, display considerable year‐to‐year variability, complicating efforts to determine suitable or preferred habitats. After returning to their breeding range, Black‐billed Cuckoos (Coccyzus erythropthalmus) and Yellow‐billed Cuckoos (C. americanus) are thought to range widely before nesting, resulting in high rates of interannual breeding‐site turnover, potentially contributing to conflicting habitat associations found in past studies. However, difficulty detecting these rare and declining species could lead to overinflated estimates of interannual turnover. Using broadcast surveys to increase detection probability, we collected detection/non‐detection data in 2019 and 2020 at 41 publicly owned sites in Illinois and performed a dynamic, multi‐scale occupancy analysis for each species to separate detection probability from potential interannual turnover and determine landscape and small‐scale variables driving habitat use and occupancy dynamics. We found strong support for interannual turnover for both species based on poor performance of non‐dynamic models and variation in estimated annual occupancy (20% and 21% increase between years for Black‐billed and Yellow‐billed Cuckoos, respectively). Black‐billed Cuckoos persisted at sites with less forest in the surrounding landscape and used areas with denser understory vegetation. Yellow‐billed Cuckoos colonized sites with greater canopy cover, avoided developed landscapes, and used areas with a shorter subcanopy layer. The dynamic nature of habitat use in these two cuckoo species suggests the importance of coordinating management and conservation across a broader spatial scale. Managing for larger patches of dense shrubs in less forested landscapes would benefit Black‐billed Cuckoos while Yellow‐billed cuckoos would benefit from management creating forested areas with open understories in less‐developed landscapes.

Specialist or refugee: Microhabitat use and competition between two sympatric woodland salamanders

Article

Full-text available

Feb 2024
J ZOOL

Co‐occurrence between species may be mediated by ecological differences or competitive interactions, but the nature of these interactions can vary across spatial scales. At coarse scales, species may appear to broadly co‐occur, but at fine scales, particularly for species with small home ranges, species may utilize different aspects of the microhabitat such that co‐occurrence is limited and competitive interactions are reduced or eliminated. We investigated the microhabitat use of two morphologically and ecologically similar woodland salamanders (the Red‐backed Salamander, Plethodon cinereus, and the Northern Ravine Salamander, P. electromorphus) that are distributed throughout the Alleghany Plateau in eastern North America to determine whether they partition habitat at finer scales. We also tested if P. electromorphus is a specialist on habitat types that allow it to exclude P. cinereus, or if P. electromorphus uses lower quality habitat as a refuge to avoid P. cinereus. At a site of microsympatry, we repeatedly sampled plots during two seasons, each within a different area of the landscape, and used occupancy and abundance modeling to assess the extent of co‐occurrence and test whether the species use different microhabitat conditions. Plethodon cinereus greatly outnumbered P. electromorphus and occupied a greater proportion of plots, most plots where we detected P. electromorphus we also detected P. cinereus. In contrast to patterns documented in some montane species pairs, in which a high‐elevation habitat specialist excludes a low‐elevation generalist, we found that P. electromorphus primarily used microhabitat conditions favorable for both species, such as north‐facing slopes, yet did not have a negative effect on the abundances of P. cinereus. In the presence of an abundant competitor, microhabitat use of the less abundant species may narrow toward optimal conditions with sufficient resources to facilitate co‐occurrence.

Area -effect in breeding bird communities occurring in an archipelago of urban holm oak fragments (Rome, Central Italy)

Article

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Feb 2012
VIE MILIEU

We carried out a study on breeding bird communities occurring in an archipelago of 32 holm oak fragments in an urbanized landscape (Rome, central Italy). The log-transformed species-area relationship is comparable with other “insular” situations obtained from analogous mainland fragmented landscapes. We observed a quick decrease of species number when area size is lower than 2 hectares, with a significant threshold at 1 ha, unlike rural areas in which a quick species decrement occurs on a higher area size range (< 10 hectares). Species appear differently sensitive to area size of the fragments with significant responses in Dendrocopos major, Aegithalos caudatus, Sitta europaea, Parus major, Certhia brachydactyla and Fringilla coelebs. Considering the recreational role of the biodiversity for human populations inhabiting large metropolitan areas, the threshold in size (about 1 ha in fragment area) evidenced in this study may be useful for urban park management strategies.

Assessment of the Influence of Spatial Scale and Type of Land Cover on Urban Landscape Pattern Analysis Using Landscape Metrics

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Feb 2024

Landscape metrics are widely used to measure the spatial pattern of landscapes. However, there are important gaps in their application. For instance, landscape metrics are sensitive to the spatial scale of analysis (i.e., extent and resolution) but while the influence of extent and resolution has been previously studied, their interaction has rarely been studied. In addition, studies assessing the influence of spatial scale on landscape metrics have scarcely paid attention to the impacts of land cover on this assessment, which reduces the generalisability or comparability of studies. Furthermore, as there are numerous landscape metrics that have been developed, these metrics exhibit degrees of correlation. Considered together, these limitations make it challenging to compare results across studies and form synthesis. We suggest that identifying a parsimonious set of metrics to promote comparability of studies will be desirable. We used Singapore as a case study to analyse how 11 commonly used landscape metrics responded to changing extents (ranging from 60 m × 60 m to 1200 m × 1200 m) in relation to resolution (Landsat 8, Sentinel-2, and WorldView-3) and land cover (vegetation and impervious surface). We used principal component analysis to identify bundles of metrics and recommend a set of common metrics across a combination of extent-resolution-land cover combinations. We highlight key observations from the study: 1) the response of all metrics to changes in spatial scale and land cover can be modelled with reasonable accuracy (indicated by model performance: R² > 0.8); 2) different types of mathematical functions (e.g., linear, logarithmic) were found suitable for the response curve of metrics, suggesting different metrics responded differently to changing scales; 3) a consistent pattern of change for individual metrics was observed across extents, resolutions, and land covers; and 4) four metrics, PLAND (the proportional area of a landscape occupied by a certain land cover, expressed as percentage), SHAPE_AM (indicates the geometrical shape complexity of patches of a given land cover), PD (indicates the number of patches of a certain land cover type per hectare of the landscape that is an indication of the fragmentation level), and ENN_AM (indicates how close the patches of a certain land cover are in relation to one another), can adequately explain the spatial pattern across the studied extents, resolutions, and land covers. Our findings advance the knowledge of and promote comparability of studies on spatial pattern quantification using landscape metrics.

Spatial prediction of plant invasion using a hybrid of machine learning and geostatistical method

Article

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Jun 2024

Modeling ecological patterns and processes often involve large‐scale and complex high‐dimensional spatial data. Due to the nonlinearity and multicollinearity of ecological data, traditional geostatistical methods have faced great challenges in model accuracy. As machine learning has increased our ability to construct models on big data, the main focus of the study is to propose the use of statistical models that hybridize machine learning and spatial interpolation methods to cope with increasingly large‐scale and complex ecological data. Here, two machine learning algorithms, boosted regression tree (BRT) and least absolute shrinkage and selection operator (LASSO), were combined with ordinary kriging (OK) to model plant invasions across the eastern United States. The accuracies of the hybrid models and conventional models were evaluated by 10‐fold cross‐validation. Based on an invasive plants dataset of 15 ecoregions across the eastern United States, the results showed that the hybrid algorithms were significantly better at predicting plant invasion when compared to commonly used algorithms in terms of RMSE and paired‐samples t‐test (with the p‐value < .0001). Besides, the additional aspect of the combined algorithms is to have the ability to select influential variables associated with the establishment of invasive cover, which cannot be achieved by conventional geostatistics. Higher accuracy in the prediction of large‐scale biological invasions improves our understanding of the ecological conditions that lead to the establishment and spread of plants into novel habitats across spatial scales. The results demonstrate the effectiveness and robustness of the hybrid BRTOK and LASOK that can be used to analyze large‐scale and high‐dimensional spatial datasets, and it has offered an optional source of models for spatial interpolation of ecology properties. It will also provide a better basis for management decisions in early‐detection modeling of invasive species.

The Drape: a new way to characterize ecosystem states, dynamics, and tipping points from process-based models

Article

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Jul 2023

There are many ways to study ecosystem dynamics, all having several issues. Main limitations of differential equation systems are the necessarily small number of interactions between few variables used, and parameter values to be set before the system dynamics can be studied. Main drawbacks of large-scale snapshot observation datasets to build a stability landscape are assuming that the most represented conditions are the most stable states, and using the computed landscape to directly study the system’s dynamics. To remedy these aforementioned shortcomings and study complex systems based on the processes that characterize them without having to limit the number of variables, neither set parameter values, nor to use observations serving both model buildup and system’s dynamics analysis, we propose a geometric model as an additional and novel aid to study ecosystem dynamics. The Drape is a generic multi-dimensional analysis, derived from process-based model datasets that include disturbances. We illustrate the methodology to apply our concept on a continental-scale system and by using a mechanistic vegetation model to obtain values of state variables. The model integrates long-term dynamics in ecosystem components beyond the theoretical stability and potential landscape representations currently published. Our approach also differs from others that use resolution of differential equation systems. We used Africa as example, representing it as a grid of 9395 pixels. We simulated each pixel to build the ecosystem domain and then to transform it into the Drape – the mean response surface. Then, we applied a textural analysis to this surface to discriminate stable states (flat regions) from unstable states (gradient or crest regions), which likely represent tipping points. Projecting observed data onto the Drape surface allows testing ecological hypotheses, such as illustrated here with the savanna-forest alternative stable states, that are still today debated topics, mainly due to methods and data used. The Drape provides new insights on all ecosystem types and states, identifying likely tipping points (represented as narrow ridges versus stable states across flat regions), and allowing projection and analysis of multiple ecosystem types whose state variables are based on the same three variables.

Using the full potential of Airborne Laser Scanning (aerial LiDAR) in wildlife research

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Jun 2024

Species' habitats are strongly influenced by the 3‐dimensional (3D) structure of ecosystems. The dominant technique used to measure 3D structure is Airborne Laser Scanning (ALS), a type of LiDAR (Light Detection and Ranging) technology. Airborne Laser Scanning captures fine‐scale structural information over large spatial extents and provides useful environmental predictors for habitat modeling. However, due to technical complexities of processing ALS data, the full potential of ALS is not yet realized in wildlife research, with most studies relying on a limited set of 3D predictors, such as vegetation metrics developed principally for forestry applications. Here, we highlight the full potential of ALS data for wildlife research and provide insight into how it can be best used to capture the environmental conditions, resources, and risks that directly determine a species' habitat. We provide a nontechnical overview of ALS data, covering data considerations and the modern options available for creating custom, ecologically relevant, ALS predictors. Options included the following: i) direct point cloud approaches that measure structure using grid, voxel, and point metrics, ii) object‐based approaches that identify user‐defined features in the point cloud, and iii) modeled environmental predictors that use additional modeling to infer a range of habitat characteristics, including the extrapolation of field acquired measurements over ALS data. By using custom ALS predictors that capture species‐specific resources, risks, and environmental conditions, wildlife practitioners can produce models that are tailored to a species' ecology, have greater biological realism, test a wider range of species‐environment relationships across scales, and provide more meaningful insights to inform wildlife conservation and management.

Ecological scales of effect vary across space and time

Article

Full-text available

Jun 2024
ECOGRAPHY

Brent Pease

The spatial scale at which an environmental variable is summarized can have considerable impacts on ecological inference of species distribution and abundance. While several analytical approaches have emerged to determine biologically relevant spatial scales – the spatial scale that most strongly influences the ecological patterns observed – identifying key ecological drivers of scale of effect is still underway. Additionally, several predicted ecological drivers of scale of effect can vary across space and time, but little research on spatiotemporal patterns has occurred. Here, I assessed spatial and temporal variation in scales of effect across 32 North American bird species using 18 years of empirical data from the North American breeding bird survey. Scale estimation was then coupled with trait‐based analyses and hypotheses testing of underlying processes of spatial and temporal variation in scales of effect. All 32 species tested exhibited varied scales of effect across years (average annual scales of effect ranging from 0.2 to 4.97 km) and Bird Conservation Regions (BCR), with spatial variability being the most pronounced. Trait‐based analyses revealed a contrary relationship between hand‐wing index, body size, and scale of effect, though the strength of this relationship was contingent on migratory status. Temporal variation in scales of effect was best explained by changes in human development over time, indicating that avian space use can be explained by an increasing human footprint. Additionally, relative population size, consistent with theoretical predictions stemming from density‐dependent population dynamics, explained notable variation in spatial and temporal scales of effect. These findings contribute to the growing landscape ecology literature by providing empirical evidence for hypothesized drivers of scales of effect. By delineating species‐specific scales of effect and elucidating their ecological drivers, this study enhances our understanding of spatial and temporal scales in ecological processes, aiding conservation efforts in a rapidly changing world.

Mosquito population dynamics is shaped by the interaction among larval density, season, and land use

Preprint

Full-text available

Jun 2024

English) Understanding how variation in key abiotic and biotic factors interact at spatial scales relevant for mosquito fitness and population dynamics is crucial for predicting current and future mosquito distributions and abundances, and the transmission potential for human pathogens. However, studies investigating the effects of environmental variation on mosquito traits have investigated environmental factors in isolation or in laboratory experiments that examine constant environmental conditions that often do not occur in the field. To address these limitations, we conducted a semi-field experiment in Athens, Georgia using the invasive Asian tiger mosquito ( Aedes albopictus ). We selected nine sites that spanned natural variation in impervious surface and vegetation cover to explore effects of the microclimate (temperature and humidity) on mosquitoes. On these sites, we manipulated conspecific larval density at each site. We repeated the experiment in the summer and fall. We then evaluated the effects of land cover, larval density, and time of season, as well as interactive effects, on the mean proportion of females emerging, juvenile development time, size upon emergence, and predicted per capita population growth (i.e., fitness). We found significant effects of larval density, land cover, and season on all response variables. Of most note, we saw strong interactive effects of season and intra-specific density on each response variable, including a non-intuitive decrease in development time with increasing intra-specific competition in the fall. Our study demonstrates that ignoring the interaction between variation in biotic and abiotic variables could reduce the accuracy and precision of models used to predict mosquito population and pathogen transmission dynamics, especially those inferring dynamics at finer-spatial scales across which transmission and control occur.

On the emergence of ecosystem decay: A critical assessment of patch area effects across spatial scales

Article

Full-text available

Jun 2024
BIOL CONSERV

Recent analyses suggest that positive patch area effects on biodiversity occur ubiquitously when comparing equal-effort samples from remnant habitat patches. The mechanisms underlying the emergence of this so-called "ecosystem decay" remain poorly understood despite conservation relevance. We leverage spatially-explicit information on the occurrence of plant species across the Swiss Alps (415 plots, 668 species) to test two mechanisms compatible with the emergence of patch-scale ecosystem decay: (i) plots sampled within small patches might have lower biodiversity than plots sampled within large patches (plot-scale decay hypothesis), and (ii) plots sampled within large patches might share a lower proportion of species (turnover hypothesis). We found that patch-scale ecosystem decay occurs also in our system. While plots sampled in large patches tended to be more dissimilar, supporting the turnover hypothesis, we did not find support for the plot-scale decay hypothesis. Additionally, distance between plots and elevational changes explain turnover between plots better than patch area effects. Taken together, these results indicate that applications of ecosystem decay in biodiversity conservation require a better understanding of the mechanisms that potentially underlie this pattern. Patch area effects might be less important than previously assumed when assessing landscape-scale biodiversity, because such effects can be confused with the effects of distance-decay in community similarity, environmental heterogeneity, and sampling effort. More broadly, our findings align with mounting evidence that protecting as much habitat as possible-regardless of whether such habitat exists continuous or fragmented-might be the most effective means to sustain biodiversity across human-dominated landscapes.

A checklist of tree species in the biological garden of Obafemi Awolowo University, Ile-Ife, Nigeria

Article

Full-text available

May 2024

A study was conducted to investigate the depletion of tree species and inventory in the Biological Garden of Obafemi Awolowo University (OAU), Ile-Ife. The study was aimed at creating a checklist of tree species in the study area. Data collection was done by dividing the study area into five sampling plots selected at random. The results indicated the presence of 72 tree species belonging to 23 families, with a total of 460 individual trees. The most common tree species found were Albizia zygia (DC.) J.F. Macbr and Alstonia boonei. The Fabaceae family had the highest percentage composition of 20.8%, making it the dominant family. The study showed a significant difference between the current and a previous survey, with the average composition of the current survey being 4.75 ± 8.30 and the previous one being 10.15 ± 16.53. This survey has provided an overview of the tree species growing in the Biological Garden of OAU, Ile-Ife. The flora richness of the identified trees are also reported in this study. The species richness of trees in the study area can be improved by controlling the indiscriminate felling of trees and other anthropogenic activities that can result in the depletion of the vegetation.

Unraveling the characteristic spatial scale of habitat selection for forest grouse species in the boreal landscape

Article

Full-text available

Jul 2024
FOREST ECOL MANAG

The characteristic spatial scale at which species respond strongest to forest structure is unclear and species-specific and depends on the degree of landscape heterogeneity. Research often analyzes a pre-defined spatial scale when constructing species distribution models relating forest variables with occupancy patterns. This is a limitation, as forest characteristics shape the species use of habitat at multiple spatial scales. To explore the drivers of this relationship, we conducted an in-depth investigation into how scaling forest variables at biologically relevant spatial scales affects occupancy of grouse species in boreal forest. We used 4,790 grouse observations (broods and adults) collected over 39,303 stands for 15 years of four forest grouse species (capercaillie, black grouse, hazel grouse, and willow grouse) obtained from comprehensive Finnish wildlife triangle census data and forest variables obtained from Airborne Laser Scanning and satellite data originally sampled at 16 m resolution. We fitted Generalized Additive Mixed Models linking grouse presence/absence in the Finnish boreal forest with forest stand structure and composition. We estimated the effects of predictor variables aggregated at three spatial scales reflecting the species use of the landscape: local level at stand scale, home range level at 1 km radius, and regional level at 5 km radius. Multi-grain models considering forest-species relationships at multiple scales were used to evaluate whether there is a specific scale at which forest characteristics best predict local grouse occupancy. We found that that the spatial scale affected the predictive capacity of the grouse occupancy models and the characteristic scale of habitat selection was the same (i.e., stand scale) among species. Different grouse species exhibited varying optimal spatial scales for occupancy prediction. Forest structure was more important than compositional diversity in predicting grouse occupancy irrespective of the scale. A limited number of forest predictors related to availability of multi-layered vegetation and of suitable thickets explained the occupancy patterns for all the grouse species at different scales. In conclusion, modeling grouse occupancy using forest predictors at different spatial scales can inform forest managers about the scale at which the species perceive the landscape. This evidence calls for an integrated multiscale approach to habitat modelling for forest species.

Macroscale Habitat Assessment and Suitability Modeling of Riverine-Segregated Eco-Geographic Units of Church's Sideband (Monadenia churchi), within and surrounding the Greater Trinity Basin, Northern California, USA

Article

Full-text available

May 2024

Robert Miles Sullivan

Church's Sideband (Monadenia churchi) is a medium-sized endemic terrestrial snail with a broad geographic distribution. It provides an excellent opportunity to evaluate habitat variance across a diverse geologic, topographic, and ecologic landscape. Herein I document and model variance in macrohabitat characteristics of five riverine-segregated Eco-geographic Units (populations) within the range of the species (Mad and Sacramento rivers, and Northern, South-Central, and Western basins). The most common forest cover-types were Sierra Mixed Conifer (49.6%), Douglas Fir (14.1%), and Montane Hardwood-conifer (8.7%). Statistical comparisons showed significant differences in 93.3% of the cover-types among groups. Principal Components Analysis of macroscale biotic and abiotic ecological variables accounted for 51.7% of the combined variance along both vectors for the species. K-means clustering using Multidimensional Scaling showed good separation of point-samples for the Sacramento River and Western Basin, but there was considerable overlap in point-samples among the remaining groups. All Habitat Suitability Models showed suitable habitat widely distributed throughout the range of M. churchi, but most areas consisted of Low suitability interspersed with few areas of Moderate to High "quality" habitat. For all groups, Generalized Additive Model regression of grid-cell density against macroclimatic co-variates exhibited the best fit compared to models of Forest Structure and Exposure-Distance to Nearest Stream. Dot-plots of variable importance, produced by Random Forest Regression, showed that predictor categories with importance values > 10 were: 1) Macroscale Climate (64.0%, n = 78), followed by Exposure-Distance to Nearest Stream (20.0%), and Forest Stand Structure (16.0%).

Ecological Requirements for Abundance and Dispersion of Brazilian Yellow Fever Vectors in Tropical Areas

Article

Full-text available

May 2024
Int J Environ Res Publ Health

In the Americas, wild yellow fever (WYF) is an infectious disease that is highly lethal for some non-human primate species and non-vaccinated people. Specifically, in the Brazilian Atlantic Forest, Haemagogus leucocelaenus and Haemagogus janthinomys mosquitoes act as the major vectors. Despite transmission risk being related to vector densities, little is known about how landscape structure affects vector abundance and movement. To fill these gaps, we used vector abundance data and a model-selection approach to assess how landscape structure affects vector abundance, aiming to identify connecting elements for virus dispersion in the state of São Paulo, Brazil. Our findings show that Hg. leucocelaenus and Hg. janthinomys abundances, in highly degraded and fragmented landscapes, are mainly affected by increases in forest cover at scales of 2.0 and 2.5 km, respectively. Fragmented landscapes provide ecological corridors for vector dispersion, which, along with high vector abundance, promotes the creation of risk areas for WYF virus spread, especially along the border with Minas Gerais state, the upper edges of the Serra do Mar, in the Serra da Cantareira, and in areas of the metropolitan regions of São Paulo and Campinas.

Methods for implementing integrated step-selection functions with incomplete data

Article

Full-text available

May 2024

Integrated step-selection analyses (iSSAs) are versatile and powerful frameworks for studying habitat and movement preferences of tracked animals. iSSAs utilize integrated step-selection functions (iSSFs) to model movements in discrete time, and thus, require animal location data that are regularly spaced in time. However, many real-world datasets are incomplete due to tracking devices failing to locate an individual at one or more scheduled times, leading to slight irregularities in the duration between consecutive animal locations. To address this issue, researchers typically only consider bursts of regular data (i.e., sequences of locations that are equally spaced in time), thereby reducing the number of observations used to model movement and habitat selection. We reassess this practice and explore four alternative approaches that account for temporal irregularity resulting from missing data. Using a simulation study, we compare these alternatives to a baseline approach where temporal irregularity is ignored and demonstrate the potential improvements in model performance that can be gained by leveraging these additional data. We also showcase these benefits using a case study on a spotted hyena (Crocuta crocuta).

Current Status of Research on Wildland Fire Impacts on Soil Environment and Soil Organisms and Hotspots Visualization Analysis

Article

Full-text available

May 2024

Ecosystems are frequently disturbed by fires that have an important impact on the soil environment and the composition of soil organisms. In order to provide a baseline for the current research and identify trends on the effects of wildland fire on soil environment and biological changes, the available literature was identified from the Web of Science database, covering the period from 1998/1998/1999 (the year of the earliest publication in this field) to 2023. A bibliometric analysis was performed and the data were visually displayed for the number of publications, countries, authors, research institutions, and keywords representing research hotspots. Specifically, the effects of wildland fire on the soil environment, on soil microorganisms and on soil fauna were analyzed. The results show that the annual number of publications describing effects of wildland fire on the soil environment and on soil microorganisms are increasing over time, while those describing effects on soil fauna are fewer and their number remains constant. The largest number of papers originate from the United States, with the United States Department of Agriculture as the research institution with the largest output. The three authors with the largest number of publications are Stefan H. Doerr, Manuel Esteban Lucas-Borja and Jan Jacob Keizer. The research hotspots, as identified by keywords, are highly concentrated on wildfire, fire, organic matter, and biodiversity, amongst others. This study comprehensively analyzes the current situation of the research on the effects of wildland fire on changes in the soil environment and organisms, and provides reference for relevant scientific researchers in this trend and future research hotspots.

The Effect of Spatial Scale on the Prediction of Tropical Forest Attributes from Image Texture

Article

Full-text available

Apr 2024

The availability of high-resolution satellite imagery has boosted the modelling of tropical forest attributes based on texture metrics derived from grey-level co-occurrence matrices (GLCMs). This procedure has shown that GLCM metrics are good predictors of vegetation attributes. Nonetheless, the procedure is also sensitive to the scale of analysis (image resolution and plot size). This study aimed to analyse the effect of spatial scale on the modelling of forest attributes, and to provide some ecological insight into such effect. Nineteen 32 × 32 m sampling plots were used to quantify forest structure (basal area: BA; mean height: H; standard deviation of height, HSD; density, D; and aboveground biomass, AGB). The 19 plots were subdivided into four 16 × 16 m, one of which was subdivided into four 8 × 8 m plots. To match this design, 12 GLCM metrics were calculated from a GeoEye-1 image (pixel size ≤ 2 m) using a 5-, 9-, and 21-pixel window from the R, NIR, NDVI, and EVI bands. For each of the windows, we modelled the five structural variables as linear combinations of the 12 metrics through linear models. The modelling potential ranged from high (R2 = 0.70) to low (0.11). H was the best-predicted attribute; this occurred at the smallest scale, with increasing scales producing lower R2 values. The second best-predicted attribute was HSD, which peaked at the intermediate scale. D and AGB displayed a similar pattern. BA was the only attribute best predicted at the largest scale. Thus, in predicting tropical forest attributes from GLCM-derived texture metrics, the spatial scale to be used should reflect the spatial scale at which ecological processes occur. Therefore, understanding how ecological processes express themselves in a remotely sensed image becomes a critical task.

Urban Matrices Threaten Patch Occurrence of Howler Monkeys in Anthropogenic Landscapes

Article

Full-text available

Apr 2024

Habitat modification due to human activities threatens species survival. While some species can inhabit habitat patches in anthropogenic landscapes, their occurrence often depends on landscape structure. We assessed the effects of landscape structure on brown howler monkey (Alouatta guariba clamitans) occurrence in an urban scenario. We conducted censuses in 59 forest patches from 2014 to 2016 in Rio Grande do Sul State, Brazil. We evaluated patch occurrence (presence/absence) in response to landscape composition (forest cover, arboreal crops, urban areas, open areas, and water) and configuration (patch density), considering the scale of effect. Water, urban, and open areas were the most important predictors of howler presence. Their presence was notably higher in landscapes with more water, likely because these landscapes consist of rural areas with low urbanization, less farming, and relatively high forest cover. Presence of howlers was positively associated with forest cover and negatively related to urban areas, open areas, and arboreal crops. Resource scarcity and increased mortality risks from human pressures, such as domestic dog attacks, electrocution, and roadkill on these land covers may explain these relationships. We highlight the importance of conserving and increasing forest cover in anthropogenic landscapes to protect species reliant on forested habitats, like howler monkeys.

Using dashboards for the study of wetland diversity in Venezuela

Article

Full-text available

Apr 2024

RESUMEN Los tableros, paneles de información, cuadros de mando, o en inglés "dashboards", permiten visualizar grandes volúmenes de datos almacenados en un computador, servidor o directamente en internet, de forma que, si se actualiza el archivo fuente, inmediatamente se observan cambios en los resultados proyectados (tablas, gráficos y mapas), generando visualizaciones interactivas y fáciles de compartir con terceros. El objetivo de este trabajo fue elaborar un tablero para estudiar la diversidad de especies vegetales en humedales de Venezuela, que pueda ser consultado libremente con fines de investigación, manejo o conocimiento general. Incluye las coordenadas geográficas, listado de especies vegetales y las características disponibles de agua y suelo en 42 humedales ubicados en los estados Miranda, Bolívar y Sucre, clasificándolos por tipo de hábitat. El tablero se realizó con Google Looker® para describir los niveles de nitrógeno, fósforo, oxígeno disuelto, salinidad y conductividad en el agua; así como salinidad, pH, porcentaje de materia orgánica, arena, arcilla y limo en el suelo. En los 42 humedales se encontraron 139 especies con un promedio de 3,3 especies por humedal. El 55,6% de los humedales estuvieron en hábitats de pantano; 16,7% en lagunas y en canales o caños 7,4% en manglares ribereños y 3,7% en manglares lagunares. Se produjo un mapa para identificar los humedales por tipo de hábitat, pudiendo elegir la distribución de una o más especies mediante un filtro. La consulta del tablero puede efectuarse de forma libre y gratuita desde cualquier dispositivo con acceso a internet, sin instalar ninguna aplicación o programa. Palabras clave: diversidad de plantas, ecosistemas, humedales, tableros, Venezuela. INTRODUCCIÓN Los tableros de control, paneles de información o cuadros de mando, conocidos comúnmente por su denominación en inglés "dashboards" son herramientas informáticas de visualización que conectan la información recopilada con una interfaz gráfica donde se construyen uno o más tipos de visualizaciones. Su nombre hace referencia a los paneles de control de los autos o los aviones, donde se monitorea el estado de todos los indicadores que es necesario controlar durante un desplazamiento. La información que se carga en los tableros puede proceder de distintas fuentes como una o varias hojas de cálculo o archivos de valores separados por comas (CSV) u otro formato estructurado en filas y columnas. Esta

Standardising field‐based assessment of invasion degree: A case study in two habitats of Reunion Island

Article

Full-text available

Mar 2024

Biological invasions represent one of the major threats to biodiversity conservation, especially in island ecosystems. Field‐based assessments of the invasion degree are required for managing and monitoring invaded habitats but there is no unifying measure available in the literature. Here, we developed a standardised method for quantifying invasion degree based on four metrics: alien and native species cover, alien species richness, the occurrence frequency of alien species and invasion level, and demonstrated its use in two contrasted habitats of Reunion Island. This rapid survey quantified relative abundance and diversity of alien plant species among three vegetation strata (herbaceous, shrub and tree) in a systematic sampling. In lowland tropical forest, it took 40 person days to survey 150 ha (344 plots), and 52 person days in subalpine vegetation to survey 125 ha (304 plots). Our results showed that the herbaceous stratum was the most invaded in terms of invasion level; more than 45% in lowland tropical forest and almost 55% in subalpine vegetation. Based on cluster analysis and kriging, we mapped three different levels of invasion highlighting potential invasion fronts. We found that it was important to differentiate invasion degree per vegetation strata as mean alien cover was significantly different between strata at each site. This method is suitable for the majority of protected areas where fine‐scale assessment is required to characterise the spatial pattern of plant invasions, monitor invasive species and identify invasion foci to control or populations of emerging species to eradicate.

Geographic Information System (GIS) for ecology: a bibliometric network analysis

Article

Full-text available

Mar 2024

Introduced in 1960s to store, analyse, and manipulate data collected for the Canada Land Inventory by mapping information about soils, agriculture, recreation, wildlife, waterfowl, forestry and land use, since their origins Geographic Information Systems (GISs) have had a fundamental role in the study of the environment. As computers systems for capturing, storing, checking, and displaying data related to positions on Earth's surface, GISs have quickly become an effective and powerful tool for addressing ecological issues, analysing the relationship between living things and their habitats, assessing the environmental impact of man-made transformations of a territory. This article aims to show and discuss the results of a study concerning quantitative distribution of GIS for ecology in literature from Scopus database using bibliometric analysis. Bibliometric analysis is a scientific computer assisted review methodology to explore the major research interests in scientific literature, so to identify core research authors, as well as their relationship, by covering articles, conference papers, book chapters and reviews related to a given topic or field. The high number of scientific manuscripts published on the subject (5,204) in the analysed period (1979-2021), remarked the soundness of this topic. While China shows the greatest number of published documents, USA is the country with the most cited documents. Specifically, "remote sensing", "spatial analysis" and "land use" are the keywords most frequently linked to GIS and ecology, so to underline respectively three aspects: the relevance of environment monitoring by satellite, airplane or drone, the utility of relating ecological questions to the geo-localization, the necessity of produce thematic maps for describing the economic and cultural activities (e.g., agricultural, residential, industrial, and recreational uses) that are practiced at a given place. Since the study shows that trend of publications focusing on the application of GIS for ecology is increasing, further growing is expected in the next future, also considering the ductility that these computer systems provide in different fields.

High-resolution remotely sensed data characterizes indices of avifaunal habitat on private residential lands in a global metropolis

Article

Full-text available

Mar 2024
ECOL INDIC

Urban ecosystems are dominated by private lands which poses a significant hurdle to performing field-based assessment of wildlife. An alternative approach is to characterize indices of animal habitat in difficult-to-access areas using data from airborne remote sensing platforms. Characterizing indices of wildlife habitat using remotely sensed data is common in natural systems but has received less attention within urban ecosystems. We tested the utility of using remotely sensed data from high-resolution airborne sensors, including LiDAR, a measure of vertical habitat structure, NDVI, a measure of greenness, image texture, a measure of horizontal habitat structure, and parcel level land-cover data, along with field-based street-tree measurements to predict bird abundance and richness across Greater Los Angeles, California, USA. We surveyed birds and gathered street-tree data on public lands of residential neighborhoods and processed the remote sensing data in 50-m and 300-m circular buffers of bird survey locations to capture data primarily on private, residential land across three winter field seasons (2016-18, 2019/20) at 23 locations along a tree-canopy cover gradient. Data from LiDAR processed as an index for the density of trees summarized in the 50-m and 300-m extents were the strongest univariate predictors of avifaunal abundance and richness explaining 75 % and 74 % of the likelihood in fitted models. NDVI, image texture, land cover, and street-tree density measures were weaker univariate predictors than models fitted with LiDAR data. Models including LiDAR and ground-based street-tree measurements accounted for upwards of 80 % of the variability in avifaunal abundance and richness, particularly for bird species associated with trees and shrubs. We recommend the prioritization of high-resolution remote sensing data, particularly LiDAR, in combination with field-based habitat measures e.g., street trees, to characterize indices of avifaunal habitat on public and private lands of cities, which could help to improve our understanding of the distribution of birds across urban areas.

Analysis and Quantification of the Distribution of Marabou (Dichrostachys cinerea (L.) Wight & Arn.) in Valle de los Ingenios, Cuba: A Remote Sensing Approach

Article

Full-text available

Feb 2024

Cuba is struggling with a growing environmental problem: the uncontrolled spread of the allochthonous weed species marabou (Dichrostachys cinerea) throughout the country. Over the last 70 years, marabou has become a formidable invasive species that poses a threat to Cuban biodiversity and agricultural productivity. In this paper, we present a free and affordable method for regularly mapping the spatial distribution of the marabou based on the Google Earth Engine platform and ecological surveys. To test its accuracy, we develop an 18-year remote sensing analysis (2000–2018) of marabou dynamics using the Valle de los Ingenios, a Cuban UNESCO World Heritage Site, as an experimental model. Our spatial analysis reveals clear patterns of marabou distribution and highlights areas of concentrated growth. Temporal trends illustrate the aggressive nature of the species, identifying periods of expansion and decline. In addition, our system is able to detect specific, large-scale human interventions against the marabou plague in the area. The results highlight the urgent need for remedial strategies to maintain the fragile ecological balance in the region.

Chapter 8 Individual-based models

Chapter

Full-text available

Jan 2018

Simon James Pittman

Chapter 2 Mapping and quantifying seascape patterns

Chapter

Full-text available

Feb 2024

Simon James Pittman

Dose scale matter?: scale and research traditions (In Thai)

Article

Jul 2019

Scale is a central tenet of spatial–related research; however, the “scale issues” in landscape architecture and environmental planning have often been taken for granted and rarely been questioned. This paper explores the issues of scale through reviewing literature from two disciplines tied to spatial research, which are geography and landscape ecology. These two disciplines put the scale issues at the forefront of their studies, and they are deemed appropriate since both provide fundamental knowledge for many fields, including landscape architecture and environmental planning, that examine human–environment systems. By situating scale in research traditions, this paper explains what scale is and explores “scale” from two schools of thought–the science of scale and the social construction of scale. The paper urges to discuss the issues of scale explicitly at the beginning of the research to avoid confusion among researchers. The paper also argues that, fundamentally, by understanding scale issues and problems from various perspectives would not only help ways in which the complex spatial phenomena can be conceptualized, investigated and managed through multi–scalar frameworks, but also encourage teamwork in multi–disciplinary research.

SEraster: a rasterization preprocessing framework for scalable spatial omics data analysis

Preprint

Full-text available

Feb 2024

Motivation Spatial omics data demand computational analysis but many analysis tools have computational resource requirements that increase with the number of cells analyzed. This presents scalability challenges as researchers use spatial omics technologies to profile millions of cells. Results To enhance the scalability of spatial omics data analysis, we developed a rasterization preprocessing framework called SEraster that aggregates cellular information into spatial pixels. We apply SEraster to both real and simulated spatial omics data prior to spatial variable gene expression analysis to demonstrate that such preprocessing can reduce resource requirements while maintaining high performance. We further integrate SEraster with existing analysis tools to characterize cell-type spatial cooccurrence. Finally, we apply SEraster to enable analysis of a mouse pup spatial omics dataset with over a million cells to identify tissue-level and cell-type-specific spatially variable genes as well as cooccurring cell-types that recapitulate expected organ structures. Availability and implementation Source code is available on GitHub ( https://github.com/JEFworks-Lab/SEraster ) with additional tutorials at https://JEF.works/SEraster .

Microscale dispersion of intertidal seagrass macrofauna

Article

Full-text available

Feb 2024
MAR ENVIRON RES

Linking small mammal capture probability with understory structural complexity using a mobile laser scanning‐derived metric: A case study

Article

Full-text available

Jan 2024

Forest understory complexity is important for many species, from large herbivores such as deer to small mammals such as mice and voles. For species that utilize the forest understory on a very small scale, it is often impractical to conduct correspondingly fine‐grained manual surveys of the understory, and thus few studies consider this small‐scale variation in understory complexity and instead work with average values on a larger scale. We explored the use of a mobile laser scanning derived understory complexity measure—understory roughness—to predict the capture probability of two representative small mammal species, the yellow‐necked mouse ( Apodemus flavicollis ) and the bank vole ( Clethrionomys glareolus ). We found a positive relationship between capture probability and understory roughness for both bank voles and yellow‐necked mice. Our results suggest that mobile laser scanning is a promising technology for measuring understory complexity in an ecologically meaningful way.

Topographic gradient influences vascular epiphyte occurrence in a small watershed covered by a mature coniferous/broadleaf evergreen mixed forest in Japan

Article

Jun 2024

Aim At fine scales (<10 km in spatial resolution), only a few studies have evaluated the relationships between abiotic factors and the horizontal occurrence of vascular epiphytes. At fine scales, variation in abiotic variables can be attributed to topographic heterogeneity. For example, air humidity and wind speed are likely to vary along ridge–valley gradients, and differences in slope aspect cause variation in light intensity as well as temperature gradient along an elevation. We tested the hypothesis that the horizontal epiphyte occurrence at fine scales is influenced more by topographic gradients related to abiotic factors than by host tree size and species. We also assessed air humidity variation along the ridge–valley gradient at our study site as a way to explore its possible correlation with the epiphyte occurrence. Location A coniferous/broadleaf evergreen mixed forest in a humid temperate zone of Kochi, southwest Japan. Methods We surveyed epiphyte occurrence on 310 trees and recorded host tree size and species within a 52‐ha watershed with an elevational range of 378–777 m a.s.l. Epiphyte occurrence was modeled using three topographic variables (ridge–valley gradient, slope aspect differences and elevational gradient), host tree size and species. The effect sizes of each variable were then compared. Air humidity was measured on the valley bottom, slope and ridge throughout the year. Results Epiphyte occurrence probability increased toward the valley bottom and on larger host trees; it also varied among host tree species. Slope aspect differences and elevational gradient were less effective. The ridge–valley gradient had a greater effect than host tree size on epiphyte occurrence. Air humidity was highest at the valley bottom and lowest on the ridge. Conclusions Horizontal epiphyte occurrence was driven more by topographic gradient than by host tree size and species in a small watershed covered by a warm‐temperate broadleaf forest. This finding suggests the importance of forests at valley bottoms to support epiphyte occurrence.

Wolf Canis lupus Linnaeus, 1758

Chapter

Jun 2024

Emergent patterns of patchiness reflect decoupling between ocean physics and biology

Preprint

Full-text available

May 2024

While a rich history of patchiness research has explored spatial structure in the ocean, there is still no consensus over the controls on biological patchiness and how biogeochemical processes and patchiness relate. The prevailing thought is that physics structures biology, but this has not been tested at the basin scale with consistent in situ measurements. Here we show that the patchiness of physics and biology are decoupled at the global scale through analysis of a global dataset of in situ surface optical properties from the R/V Tara and using the slope of spatial scale vs variance to quantify patchiness. Based on analysis of ~650,000 nearly continuous (dx~150m) measurements from an underway sampling system - representing five years of consistently collected data across the Atlantic, Pacific, and Southern Oceans - we find the patchiness of physical and biological parameters are uncorrelated. We show that variance slope is an emergent property with unique patterns in biogeochemical properties that are distinct from physical tracers, yet connected to other biological tracers. These results provide context for decades of discrepancy between in situ studies, could support new tests of biogeochemical model parameterizations, and open the way for new insight into processes regulating the observed patterns.

Variation in fine-scale water table depth drives abundance of a unique semi-terrestrial crayfish species

Article

Full-text available

May 2024

With anthropogenic changes altering the environment and the subsequent decline of natural habitats, it can be challenging to predict essential habitats for elusive and difficult to study taxa. Primary burrowing crayfish are one such group due to the complexity in sampling their semi-terrestrial, subterranean habitat. Sampling burrows usually requires a labor-intensive, time-consuming excavation or trapping process. However, limited information on burrowing crayfish suggests that fine-scale habitat variation may drive burrowing crayfish habitat choice. This project aimed to evaluate the fine-scale habitat characteristics that influence burrowing crayfish presence and abundance at a large, restored-remnant grassland preserve in north-central Illinois. We documented burrow abundance and quadrat-specific habitat variables such as root biomass, canopy cover, apparent seasonal high-water table (water table) depth and dominant vegetation at sites with and without burrowing crayfish populations. Data was recorded at every quadrat and analyzed using generalized linear mixed models. A total of 21 models were created to determine what habitat variables affected burrow presence and abundance. We found that the water table depth was a significant driver of burrow presence and abundance. Root biomass and vegetation cover were not significant drivers, although they did show up in the final models, explaining the data. These findings demonstrate empirical support for previous observations from other burrowing crayfish research and demonstrate the influence of fine-scale habitat when modeling elusive taxa requirements.

Ecosystem services to support sustainable development: The modifiable areal unit problem in the transition between evaluation and management units

Article

May 2024
SUSTAIN DEV

Understanding the role of ecosystem services (ES) and their interactions at different spatial scales in territorial space governance is crucial for sustainable development. However, a unified analysis of scale and zoning effects on ES supporting sustainable development remains a theoretical and practical gap. Therefore, this study utilized the traditional concept of the modifiable areal unit problem (MAUP) to establish the ES-MAUP framework. Additionally, the highly urbanized region of Southern Jiangsu, China, was selected as a case study area to quantitatively evaluate four typical regulating ecosystem services in 2020: urban cooling (UC), flood mitigation (FM), soil conservation (SC), and net primary productivity (NPP). The spatial characteristic information of these four ES was effectively preserved with increasing spatial scale. Significant differences existed in the hotspot patterns of NPP, UC, and SC among different zoning units. Across the three zoning units, the correlations between NPP-UC, NPP-SC, and UC-SC exhibited consistent positive trends, while notable differences in correlations between other ES pairs, such as NPP-FM and UC-FM.

Heterogenous resources across sagebrush type are associated with components of offspring fitness in an avian habitat specialist

Article

May 2024
BIOL CONSERV

Variable importance and scale of influence across individual scottish wildcat hybrid habitat models

Article

May 2024
ECOL MODEL

Influencing Factors and the Establishment of a Basin Ecological Compensation Mechanism from the Perspective of Water Conservation: A Case Study of the Upper Yangtze River in China

Article

Apr 2024
J CLEAN PROD

Towards an ecological mathematics

Article

Mar 2024
INTERDISCIPL SCI REV

Siddharth Unnithan Kumar

Mathematics plays a fundamental role in ecological research, yet its uses remain strikingly separate from advances in the environmental social sciences and humanities. In this paper, I work to address this impasse and outline the motivation and scope for an ‘ecological mathematics’, an approach to doing mathematics in environmental research which foregrounds relationship, embodiment and human difference. I begin by tracing the historical emergence of mathematics in ecology, noting how life processes have been conceptualised in a way which forces them to fit the ideals of mathematical models transplanted from the physical sciences. I then investigate the cultural factors shaping the evolution of mathematical thought, eliciting a malleability in how mathematical knowledge relates to the more-than-human world. This provides a place from which to rethink the role of abstraction in ecological thought, and develop mathematical methods grounded in ecological concepts. Drawing on ethnographic and perceptual accounts of space and time, I work with topological concepts from both mathematics and the social sciences to suggest a new correspondence between these subjects, elaborating a way of employing mathematical techniques which enliven, rather than deaden, the ecologies under study. The paper concludes with important philosophical clarifications to the approach of an ecological mathematics.

Wolf Canis lupus Linnaeus, 1758

Chapter

Jan 2024

Environmental drivers of global variation in home range size of terrestrial and marine mammals

Article

Full-text available

Mar 2024
J ANIM ECOL

As animal home range size (HRS) provides valuable information for species conservation, it is important to understand the driving factors of HRS variation. It is widely known that differences in species traits (e.g. body mass) are major contributors to variation in mammal HRS. However, most studies examining how environmental variation explains mammal HRS variation have been limited to a few species, or only included a single (mean) HRS estimate for the majority of species, neglecting intraspecific HRS variation. Additionally, most studies examining environmental drivers of HRS variation included only terrestrial species, neglecting marine species. Using a novel dataset of 2800 HRS estimates from 586 terrestrial and 27 marine mammal species, we quantified the relationships between HRS and environmental variables, accounting for species traits. Our results indicate that terrestrial mammal HRS was on average 5.3 times larger in areas with low human disturbance (human footprint index [HFI] = 0), compared to areas with maximum human disturbance (HFI = 50). Similarly, HRS was on average 5.4 times larger in areas with low annual mean productivity (NDVI = 0), compared to areas with high productivity (NDVI = 1). In addition, HRS increased by a factor of 1.9 on average from low to high seasonality in productivity (standard deviation (SD) of monthly NDVI from 0 to 0.36). Of these environmental variables, human disturbance and annual mean productivity explained a larger proportion of HRS variance than seasonality in productivity. Marine mammal HRS decreased, on average, by a factor of 3.7 per 10°C decline in annual mean sea surface temperature (SST), and increased by a factor of 1.5 per 1°C increase in SST seasonality (SD of monthly values). Annual mean SST explained more variance in HRS than SST seasonality. Due to the small sample size, caution should be taken when interpreting the marine mammal results. Our results indicate that environmental variation is relevant for HRS and that future environmental changes might alter the HRS of individuals, with potential consequences for ecosystem functioning and the effectiveness of conservation actions.

Spatial extent predicts Andean epiphyte biodiversity responses to habitat loss and fragmentation across human‐modified landscapes

Article

Full-text available

Mar 2024

Aim Human‐driven landscape processes such as habitat loss and fragmentation act on biodiversity, but their effects are mediated by the spatial scale at which they are observed. We aim to analyse the scale‐of‐effects (direction and spatial extent) of landscape‐scale processes that best explain species richness and abundance across epiphyte communities. Location Neotropics, Northern Andes, Colombia, Eastern cordillera. Taxon Vascular epiphytes, Orchidaceae. Methods We used field data to unravel the scale‐of‐effect of three landscape processes—habitat loss (forest cover), fragmentation (number of patches) and edge effects (edge density)—on epiphyte biodiversity. Vascular epiphytes were sampled in the understorey across 141 plots within 23 Andean forests in the eastern Colombian cordillera We focused on the community‐level responses (species richness and total abundance) of the hyperdiverse vascular epiphyte communities using generalized linear mixed models to quantify the direction and the spatial extent of the scale‐of‐effects. Results Habitat loss and edge effects act at fine spatial extents (scale‐of‐effects = 200 m), predicting low species richness and abundance across groups. Likewise, fragmentation negatively impacts communities, but operates at larger spatial extents (scale‐of‐effects = 2000–2400 m radius). The detection of these effects is contingent upon the spatial extent and specific landscape processes involved. Models of habitat loss within a spatial extent of 800–1500 m (large confidence intervals), fragmentation below 300 m, and edge effects above 800 m show weak statistical support (marginal r ² = 0.02–0.1). Thus, the impacts of these landscape processes may be overlooked if studied at inadequate spatial extents. Main Conclusions We showed that habitat loss, fragmentation and edge effects all play a negative role on understorey epiphytic communities, but their detectability is scale dependant. The scale‐of‐effects can assist landscape designs that are beneficial for epiphytic communities, by preserving forest cover, and reducing fragmentation and exposure to edge effects at small scales (200–300 m). Conversely, landscape‐scale actions directed at reducing habitat loss and fragmentation function at larger spatial extents (>2000 m). Selecting a priori or inadequate spatial extents of analysis can obscure the detectability of landscape processes.

15-Yr Biomass Production in Semiarid Nebraska Sandhills Grasslands: Part 1—Plant Functional Group Analysis

Article

Mar 2024
RANGELAND ECOL MANAG

Incorporating Spatial Data into Ecological Risk Assessments: The Spatially Explicit Exposure Module (SEEM) for ARAMS

Chapter

Jan 2004

Description Eighteen peer-reviewed papers explore the latest information on theoretical and applied ecology, especially as it relates to characterizing environmental risks to wildlife and the requirements of environmental managers. Until recently, many areas which have low to moderate levels of chemical contamination were subjected to intrusive remediation efforts; the consequence being substantial destruction of existing wildlife habitat and low potential for enhancing better quality habitat at the affected site. This new ASTM publication addresses these issues. Topics cover

Importance of high-resolution spatial data for the detection of winter wildlife responses to edges

Article

Feb 2024
CAN J FOREST RES

Several wildlife species are thought to avoid edges of large habitat gaps, such as clear-cuts, but detailed evidence is rarely available for edges of smaller gaps. We compared the responses of nine wintering mammal species to forest edges in southern Quebec, Canada, using high-resolution spatial data from Light Detection And Ranging (LiDAR) and low-resolution photo-interpretation. We defined edges of open areas as roads, lakes, rivers, or forest open areas. We geolocated mammal snow tracks along systematic transect lines between 2009 and 2018. We compared distances of snow tracks and reference points along transects to the nearest edge with linear models. LiDAR data revealed five species avoiding forest open area edges, whereas no avoidance was shown using photo-interpretation data. Weasels (Mustela sp.) were the only species showing a positive association with forest open area edges using photo-interpreted data. No significant response was detected for river or lake edges. Four species were positively associated with road edges. We conclude that avoidance of small forest open area edges is widespread in our study area, but it can only be detected with high-resolution spatial data. Our results imply that edge effect can operate at a fine scale and using appropriate spatial resolution is crucial to detect such effects.

Broadcast burning has persistent, but subtle, effects on understory composition and structure: Results of a long-term study in western Cascade forests

Article

Mar 2024
FOREST ECOL MANAG

Approaches to forest management have changed markedly in the Pacific Northwest in recent decades, yet legacies of past management persist on the landscape. Following clearcut logging, woody residues were typically burned to reduce future fire hazard, create planting spots, facilitate natural recruitment, and retard growth of competing vegetation. We asked whether legacies of broadcast burning persist in the forest understory during the early stages of stand closure, how they manifest structurally or compositionally, whether they are altered by subsequent management (pre-commercial thinning), and how they vary with gradients in the physical environment or stand structure. We used data from 44 pairs of burned and unburned plots sampled 37–42 years after clearcut logging of mature and old-growth forests in western Oregon and Washington. Burning had persistent, but mostly subtle effects on community structure and composition. Burned plots had greater cover of early-seral species and lower cover of woody forest species. Among the latter, tall shrubs showed consistently negative responses to burning. Smaller-statured woody and herbaceous species were more variable in their responses, reflecting a greater diversity of regenerative traits. For some understory attributes, effects of burning were contingent on thinning history. For example, burning enhanced species richness and reduced species evenness, but only in unthinned sites. Conversely, burning increased the spatial variability of tall shrub cover, but only in thinned sites. In some instances, thinning compounded the effects of burning, resulting in a four-fold increase in cover of early-seral herbs and a 50% reduction in cover of forest tall shrubs relative to plots that received neither treatment. For most understory attributes, regional variation in the magnitude of the burn effect was not easily explained by burn severity, site environment, or stand structure. Collectively, our results highlight the persistent, but highly variable, effects of broadcast burning on the post-harvest development of the forest understory. They suggest that, where it is feasible, controlled burning can be used in regeneration-harvest units to achieve a variety of management objectives, with minimal effect on the forest understory.

Integrating spatial stream network models and environmental DNA to estimate current and future distributions of nonnative Smallmouth Bass

Article

Jan 2024

Objective Climate change is fueling the rapid range expansion of invasive species in freshwater ecosystems. This has led to mounting calls from natural resource managers for more robust predictions of invasive species distributions to anticipate threats to species of concern and implement proactive conservation and restoration actions. Here, we applied recent advances in fish sampling and statistical modeling in river networks to estimate the current and future watershed‐scale spatial distribution of nonnative Smallmouth Bass Micropterus dolomieu . Methods We integrated a spatial stream network (SSN) model of stream temperature, landscape environmental covariates, and Smallmouth Bass occurrence data based on environmental DNA (eDNA) detections to develop an SSN species distribution model (SDM) representing current Smallmouth Bass distributions in the Chehalis River, Washington State, a large coastal river basin of ongoing watershed‐scale restoration. The SDM was informed by spatially intensive eDNA sampling from 135 locations in the main stem and major tributaries. We then applied downscaled climate change projections to the SSN SDM to predict Smallmouth Bass range expansion in the basin by late century. Result We identified high levels of spatial autocorrelation at hydrological distances of ≤10 km in our eDNA data set, underscoring the importance of applying an SSN modeling framework. Stream temperature was identified as the most important environmental covariate explaining variability in Smallmouth Bass occurrence. Model predictions estimated that current suitable summer habitat for Smallmouth Bass habitat spans 681 km and is projected to nearly double by late century (1333 km) under a moderate climate change scenario. Current and future suitable habitat for Smallmouth Bass is prevalent in important tributaries for spring Chinook Salmon Oncorhynchus tshawytscha , a species of major conservation concern in the Chehalis River and more broadly along the Pacific coast. In both the main stem and tributaries, the SSN SDM predictions of the upstream leading edges of Smallmouth Bass closely align with (within 4.8 km) edges identified by spatially intensive eDNA sampling. Conclusion Our study highlights the value of integrating SSN models with rapidly growing eDNA data sets for accurate and precise riverine fish distribution estimation. Our application provides crucial insights for anticipating the impacts of shifting invasive species on Pacific salmon Oncorhynchus spp. in a warming world.

Large herbivore foraging and ecological hierarchies: Landscape ecology can enhance traditional foraging theory

Article

Full-text available

Dec 1987
BIOSCIENCE

Scale dependent processes in the physical and biological environment of marine birds

Chapter

Full-text available

Jan 1987

Epistemology, Experiments, and Pragmatism

Chapter

Full-text available

Jan 1988

In retrospect, what we now call complex interactions encompass several of the major advances in aquatic ecology. Some examples include the trophic-dynamic concept (Lindeman 1942), the multidimensional niche (Hutchinson 1957), size selective predation and the size efficiency hypothesis (Hrbacek et al. 1961; Hrbacek 1962; Brooks and Dodson 1965), the keystone predator concept (Paine 1966), and optimal foraging theory (Werner 1977). Recent advances offering similar benefit include the microbial loop (Riemann and Sondergaard 1986; Scavia and Fahnenstiel this volume; Porter et al. this volume), the ontogenic niche (Werner and Gilliam 1984; Crowder et al. chapter 10; Stein et al. chapter 11), chemical induction of antipredator morphological, behavioral and life history traits (Havel 1987), behavioral responses to predation (Kerfoot and Sih 1987) and the trophic cascade argument (Carpenter et al. 1985). The preceding chapters offer many specific examples of complex interactions in aquatic communities. Others will certainly appear in the near future. Chapters 10–14 develop both the general state of current understanding and the specific priorities for future work in this area of ecological research.

The Community Structure of Coral Reef Fishes

Article

Full-text available

Apr 1981

Habitat Selection by Breeding American Redstarts in Response to a Dominant Competitor, the Least Flycatcher

Article

Full-text available

Apr 1988

Through natural population changes and experimental field removals, we tested the hypothesis that Least Flycatchers (Empidonax minimus) restrict habitat use by socially subordinate American Redstarts (Setophaga ruticilla). On a 10-ha site 2-yr-and-older (ASY), but not yearling (SY), male redstarts avoided the sector occupied by flycatchers from 1975 to 1980, but preferred this sector from 1981 to 1985 when flycatchers were absent. Vegetation changed subtly on the site but could not account for the sudden shift in redstart settlement pattern. On 6 4-ha sites ASY male redstarts were most abundant in years of Least Flycatcher absence. On the 5 4-ha sites from which Least Flycatchers either disappeared independently or were removed experimentally between 1981 and 1984, redstart abundance increased on four and remained constant on the fifth; on three control areas redstart numbers declined during the same period. Least Flycatchers recolonized one removal site, and ASY redstart abundance subsequently declined. SY male redstart abundance varied inversely with that of ASY male redstarts. We conclude that flycatchers influenced the distribution of ASY male redstarts directly, and that of SY males indirectly, more than either vegetation structure or other habitat characteristics. At no spatial scale examined, however, did total redstart abundance (ASY + SY) vary inversely with that of Least Flycatchers; in fact, their total abundances correlated positively at a regional scale. These findings, combined with a model for asymmetric competition for mutually preferred habitat (Pimm et al. 1985, Rosenzweig 1985), illustrate how a socially dominant competitor could lead to a broadening rather than a narrowing of the habitat breadth of a subordinate species. We show that competitor species abundances need not vary inversely and that age classes may be affected differentially. This species interaction illustrates subtleties and complexities of how competition can modify avian habitat selection.

A Lesson in the Limitations of Field Experiments: Shrubsteppe Birds and Habitat Alteration

Article

Full-text available

Apr 1986

The habitat composition and structure within territories of birds breeding in Artemisia-dominated shrubsteppe of central Oregon were manipulated in order to assess how closely individuals track habitat in features such as territory placement or size or behavioral budgeting and space use. Territorial locations and sizes and breeding densities of horned larks Eremophila alpestris, sage sparrows Amphispiza belli and Brewer's sparrows Spizella breweri on the manipulated area and an adjacent unaltered control area were monitored. Sage sparrows, which are more closely linked to shrub (sagebrush) coverage, did not respond to manipulation at a local population level. The manipulation did affect territory placement and densities of Brewer's sparrows and horned larks in 1980-1982, but these trends were not consistent over the entire 7 yr postmanipulation period. Densities of all species varied among years. For brewer's sparrows and horned larks these variations did not parallel those in nearby census locations, but sage sparrow densities varied in the same ways over all locations. These variations appeared to parallel variations in October-April precipitation, with a 1-yr time lag. Individuals of both sparrow species altered the details of their activity budgeting, but not their substrate-use patterns, in response to manipulation. -from Authors

The importance of scale in community ecology: a kelp forest example with terrestrial analogs

Chapter

Full-text available

Jan 1984

Scale-dependent correlation of seabirds with schooling fish in a coastal ecosystem

Article

Full-text available

Sep 1986

ABSTRACT: The distribution of piscivorous seabirds relative to schooling fish was investigated by repeated censusing of 2 intersecting transects in the Avalon Channel, which carries the Labrador Current southward along the east coast of Newfoundland. Murres (primarily common murres Uria aalge), Atlantic puffins Fratercula arctica, and schooling fish (primarily capelin Mallotus villosus) were highly aggregated at spatial scales ranging from 0.25 to 15 km. Patchiness of murres, puffins and schooling fish was scale-dependent, as indicated by significantly higher variance-to-mean ratios at large measurement distances than at the minimum distance, 0.25 km. Patch scale of puffins ranged from 2.5 to 15 km, of murres from 3 to 8.75 km, and of schooling fish from 1.25 to 15 km. Patch scale of birds and schooling fish was similar in 6 out of 9 comparisons. Correlation between seabirds and schooling birds was significant at the minimum measurement distance in 6 out of 12 comparisons. Correlation was scale-dependent, as indicated by significantly higher coefficients at large measurement distances than at the minimum distance. Tracking scale, as indicated by the maximum significant correlation between birds and schooling fish, ranged from 2 to 6 km. Our analysis showed that extended aggregations of seabirds are associated with extended aggregations of schooling fish and that correlation of these marine carnivores with their prey is scale dependent.

A Hierarchical Concept of Ecosystems. (MPB-23), Volume 23

Book

Sep 2021

The Ecology of Bird Communities

Book

Sep 1989

John A. Wiens

The two volumes of John Wiens' Ecology of Bird Communities have applications and importance to the whole field of ecology. The books contain a detailed synthesis of our current understanding of the patterns of organisation of bird communities and of the factors that may determine them, drawing from studies from all over the world. By emphasizing how proper logic and methods have or have not been followed and how different viewpoints have developed historically and have led to controversy, the scope of these books are extended far beyond the study of birds. Processes and Variations discusses the way in which bird community patterns have been interpreted. This second volume examines how the complexity and variability of natural environments may influence efforts to discern and understand the nature of these communities. Graduate students and professionals in avian biology and ecology will find these volumes a valuable stimulus and guide to future field studies and theory development.

16. Challenges in the Development of a Theory of Community and Ecosystem Structure and Function

Chapter

Dec 1989

Simon Levin

The Fractal Geometry of Nature.

Article

Nov 1984

Scale-dependent processes in the physical and biological environment of marine birds

Article

Jan 1987

The analysis of community organization: The influence of equilibrium, scale and terminology

Article

Jan 1987

The Contribution Of Population And Community Biology To Conservation Science

Article

Jan 1988
Annu Rev Ecol Systemat

Daniel Simberloff

Climate and Plant Distribution

Book

Jan 1987

F.I. Woodward

Coexistence on divided habitats: mosses in the family Splachnaceae

Article

Jan 1988

P.C. Marino

Splachnaceae grow primarily on dung and have spores that are dispersed to dung by Diptera. On a local scale, few mechanisms appear to promote coexistence of Splachnaceae on a dropping. Competition between mosses is strong and individual droppings tend to be occupied by a single species. On a regional scale, dispersal may promote habitat separation between the genera while coexistence in Splachnum spp. appears to be influenced by a tradeoff between dispersal and competitive ability. Coexistence in Tetraplodon spp. is facilitated by temporal separation of sporophyte production. Resource fluctuations may also promote coexistence. -from Author

Resource Competition and Community Structure

Article

Jul 1983
Monogr Popul Biol

Chapter 5 Non-Linearities Associated with Physical and Biochemical Processes in the Sea

Chapter

Dec 1975

This chapter discusses the importance of some of the inherent non-linearities present in both physical and biochemical processes in the sea. To this end, the chapter discusses the influence of terms in the relevant mathematical equations that represent second- and higher-order effects. It is a fact of experience that, according to location and circumstance, the non-linear terms in the dynamical equations for the sea may, at one extreme, produce effects that dominate the sea's motion, or, oppositely, have quite a negligible influence. In the latter case, linearization is justified. However, even when non-linearities are significant, a linear first-order solution may constitute an initial step toward the determination of the complete motion and might provide a relatively simple theoretical framework from which to gain a better understanding of the water movements. Therefore, while wishing to stress the dangers of excessive linearization, it seems prudent at the outset to suggest that the value of linear solutions should not be underestimated.

Fractal geometry and caterpillar dispersal: Or how many inches can inchworms inch?

Article

Jan 1988

Process-response models of denudation at different spatial scales

Article

Jan 1987

F. Ahnert

The landform development model program SLOP3D, which is based on the mass balance concept, is used to investigate 1) the interaction between weathering and denudation at a point on a slope, 2) the relationships between slope form, mean denudation rate and summit denudation rate and 3) the height limit of young mountain ranges as a function of their width. -from Author

Modeling Recolonization by Neotropical Migrants in Habitats with Changing Patch Structure, with Notes on the Age Structure of Populations

Chapter

Jan 1981

Robert M. May

Scale in the Design and Interpretation of Aquatic Community Research

Chapter

Jan 1988

The scales employed in investigations of aquatic ecosystems can strongly influence interpretations of community patterns and processes. Some examples are obvious; in contrasting cladocerans and rotifers, assessments of biomass (an instantaneous time scale) provide strikingly different impressions than assessments of production (a broader time scale) (Makarewicz and Likens 1975). Other examples are more subtle but equally important; seasonal distributions of phytoplankton species over several years may indicate patterns with little predictability but distributions of functional groups of phytoplankton can indicate a periodic behavior (Bartell et al. 1978; Reynolds 1984). Explicit considerations of the scales that an observer uses in an investigation are fundamental to an understanding of aquatic systems.

SCALES OF VARIABILITY IN ESTUARINE ECOSYSTEMS

Chapter

Dec 1982

Ecological dynamics in estuaries can be characterized in terms of spatial and temporal scales of variability. Data from Bedford Basin and other inlets on the Atlantic Coast of Nova Scotia are used to examine the scales of physical forcing and the scales of biological response. We establish temporal scales for which these inlets appear to be autonomous with respect to the adjacent continental shelf (~<3 days), and develop theoretical criteria for autonomy based on the distribution of biological variability in the frequency domain. The spatial distribution of phytoplankton biomass is analyzed in the wavenumber domain. A “biological window” in the wavenumber spectrum is suggested, where growth processes are the principal determinants of the variance spectrum. On either side of this window, physical forces override biological processes. It is concluded that in estuaries, where physical forcing is often strong in amplitude and complex in frequency structure, it is particularly important to emphasize the scales of variability for both physical and biological processes and to recognize that time and space scales are intimately related.

Coherences in the horizontal distributions of phytoplankton and temperature in the upper ocean

Article

Jan 1975

The Ecological Theater and the Evolutionary Play.

Article

May 1967

Insect Outbreaks

Article

Feb 1989

Outbreak species have often devastated economically important and aesthetic resources and thus have received a great deal of attention. Although the factors thought to trigger changes in abundance have been detailed in various studies, relatively little synthesis or retrospective analysis has been attempted. This book updates and advances current thinking on the phenomenon of insect outbreaks. The 20 contributions (abstracted separately; see also 89L/04164-04176) review relevant literature in order to generate a synthesis providing new concepts and important alternatives for future research. There is a four-section arrangement: introduction to outbreaks; community structure; natural and manipulated ecosystems; biotic and abiotic factors in insect outbreaks; evolutionary consequences. -after Editors

On the relationship between abundance and distribution of species

Article

Jan 1984

J.H. Brown

PDF

Assembly of Mangrove Ant Communities: Patterns of Geographical Distribution

Article

Jun 1983

Blaine J. Cole

(1) The mechanisms by which communities of mangrove ants develop are examined. (2) Eighty-one small mangrove islands in the Florida Keys were surveyed for ant species. Islands varied four orders of magnitude in size. (3) Each of the five major species was found only on islands of a certain minimum size (MSR) or larger. (4) For two species, termed Primary species, experimental introductions showed that the MSR was due to island unsuitability. For two other species, termed Secondary species, the MSR was shown to be the result of competitive interactions with the Primary species. (5) Experiments involving the two Primary species showed that either was capable of preventing the invasion of the other species. Simultaneous introduction experiments showed that one species invariably invaded while the other invariably became extinct. (6) Behavioural interactions between all pairs of the species were tested in arena experiments. The patterns of aggression and avoidance were consistent with, and presumed to be the cause of, the experimental results and patterns of geographical distribution.

Landscape Patterns in a Disturbed Environment

Article

Mar 1987

Deciduous forest patterns were evaluated, using fractal analysis, in the U. S. Geological Survey 1: 250,000 Natchez Quadrangle, a region that has experienced relatively recent conversion of forest cover to cropland. A perimeter-area method was used to determine the fractal dimension; the results show a different dimension for small compared with large forest patches. This result is probably related to differences in the scale of human versus natural processes that affect this particular forest pattern. By identifying transition zones in the scale at which landscape patterns change this technique shows promise for use in developing hypotheses related to scale-dependent processes and as a simple metric to evaluate changes on the earth's surface using remotely sensed data.

Effect of Spatial Arrangement of Habitat Patches on Local Population Size

Article

Apr 1988

The purpose of this study was to examine the effect of the spatial arrangement of host-plant patches on local abundance of the cabbage butterfly (Piers rapae). By considering the movement behavior of adult females, we developed a detailed simulation model of P. rapae in patchy habitats. The model was then used to predict effects of cabbage patch spatial arrangement on P. rapae egg densities for a specific spatial arrangement of cabbage patches. Field studies confirmed the predictions. The results of this study are discussed in the context of the effects of dispersal behavior on relationships between aptch spatial arrangement and local abundance. The findings are consistent with general simulation results of L. Fahrig and J. E. Paloheimo (personal observation) that suggest large dispersal distances decrease the effect of the spatial arrangement of habitat patches on local population size.

Long-Path Ftir Measurement of Atmospheric Trace Gas Concentrations

Article

Oct 1988

Extending the ecological knowledge base to larger scales will require new measurement tools. Long-path Fourier-Transform Infrared Spectroscopy (FTIR) is a promising technology because of its ability to measure the concentration of multiple trace gases simultaneously over spatial scales up to 1 km. Detection limits reaching 1@mL/KL for numerous gases make this a powerful method with the potential to study spatial patterning of biological processes, fluxes between ecosystems, important processing pathways within terrestrial and aquatic ecosystems, and scale-dependent processing phenomena. Repeated measurements down to the second range add excellent temporal capabilities. This analytical tool, drawing on the latest developments in analytical chemistry, expands the temporal and spatial scales over which ecosystem nutrient cycling energy flow, and biospheric/atmospheric interactions can be studied.

How Are Extensive, Human-Caused Habitat Alterations Expressed on the Scale of Local Bird Populations in Boreal Forests?

Article

Jul 1986

We studied long-term population changes in 43 abundant species of forest birds using line transect censuses conducted in northern Finland from 1941 to 77. Previous studies have suggested that human-caused habitat changes are a major reason for regional, long-term changes of bird populations. Birds of old taiga forests have decreased in number because of clear-cutting and forest fragmentation. Many southern species have increased during the period studied, probably partly because of an overflow of individuals from increasing populations in southern Finland, partly as a consequence of habitat changes (increase of bushy young forests and forest edges) in northern Finland. While the median northern species decreased by about one-third, the median southern species increased 5-fold in northern Finland during the study period. How do the regional patterns translate to the local scale? An area characterized by mature forest and peatlands in Simo was censused in 1959 and 1977-81. Between these censuses the area changed drastically due to clear-cutting and draining. Species trends were similar to those observed regionally but more species declined, probably because, on average, the local habitat changes were more extreme than those on the regional scale. In contrast, another local study area, a luxuriant spruce forest (Törmävaara), remained intact from a first census in 1915 until censused again in 1981-83. In this area the local stability expected was overshadowed by the regional changes: in the 1980s the reserve-like Törmävaara was no longer characterized by the typical bird species of northern old forests, but the bird populations had changed largely as in managed forests in northern Finland. This result suggests that the bird populations in small forest reserves in northern Finland are not closed but affected by the dynamics of the regional populations.

From Biogeography to Life History Theory: A Multithematic Approach Illustrated by the Biogeography of Vertebrates

Article

Sep 1987

Jacques Blondel

Hierarchy theory assumes that many ecological properties can be best interpreted by an investigation in other scales than by keeping only at the scale where they are observed. Six examples going from larger to smaller scales illustrate this approach. 1) The debate about the relations between speciation by vicariance or speciation by dispersion. 2) A demonstration of the necessity to refer to the historical development of bird faunas in order to explain modern biogeographical patterns of distribution of birds in Mediterranean forests. 3) Challenges the hypothesis of ecomorphological convergence of bird communities composed of unrelated taxa living in similar mediterranean bioclimates. 4) Processes of community organization and regulation of regional diversities of forest birds in relation to the structure and the geographical configuration of habitats. Extinction-immigration processes are very different whether the habitat is surrounded by a deep primeval forest or is an isolated woodlot. 5) The role of history and man on colonization patterns and the structure of island communities. Probability of successful colonization largely depends on species-specific histories, whether the species evolved in large tracts of homogeneous habitats or in small isolated habitats. Insular patterns of mammal communities in the Mediterranean islands cannot be explained by current theories of island biogeography because all the present species have been introduced by man in the last 8000yr. 6) The consequences of modifications of the structure of insular bird communities are explored at the level of life histories of selected species. The tradeoff of such important life history traits as the timing of reproduction, the clutch size and survival values is better explained by a detailed study of local environmental conditions than by current theories of island biogeography and demographic strategies.-from Author

Ordination: Mathematical Elegance and Ecological Naivete

Article

Mar 1973

Edward W. Beals

Principal components analysis, as a method of ordination to detect environmental influences, makes many unreal assumptions about ecological data. It does not take into account the normal-curve relationship between species success and environment, nor the ecological ambiguity of species absence in a stand. Furthermore, it uses an ecologically nonsensical centroid, and presumes a species-dimensional space. The latter is shown not to relate in any Euclidean way to environmental space. Each plant species in a pair of stands responds to the total environmental difference of those two stands, not to factors independent of those to which other species are responding. A model preferable to species-dimensional space is one which is defined by changes in vegetation from point to point (δ-vegetational space). The Bray and Curtis ordination, including the distance used, comes closer to this model than does principal components analysis. This is probably why the former method has given results that are equally satisfactory ecologically to those of more sophisticated methods, despite its alleged crudeness and frequently unwise choice of reference points. Refined techniques are being developed, which represent this vegetation model.

Scales and Global Change

Article

Sep 1989

Locating Discontinuities along Ecological Gradients

Article

Apr 1987

Population Biology of Plants

Article

Mar 1979

Stomatal Control of Transpiration: Scaling Up from Leaf to Region

Article

Dec 1986
ADV ECOL RES

Publisher Summary The study of leaf anatomy and of the mechanisms of the opening and closing of stomatal guard cells leads one to suppose that the stomata constitute the main or even the sole regulating system in leaf transpiration. Meteorologists have developed a wide variety of formulae for estimating evaporation from vegetation that are based entirely on weather variables and take no account at all of the species composition or stomatal properties of the transpiring vegetation. These “potential evaporation” formulae are widely and, to a large degree, successfully used for estimating evaporation from vegetation that is not water-stressed. Transpiration depends on stomatal conductance, net radiation receipt and upon air saturation deficit, temperature, and wind speed. Saturation deficit and wind speed vary through leaf boundary layers, through canopies, and through the atmosphere above the canopies. The sensitivity of saturation deficit to changes in stomatal conductance depends on where the saturation deficit is measured. If all of the stomata on a single leaf change aperture in unison, there may be a substantial change in saturation deficit measured at the leaf surface but a negligible change in saturation deficit measured a centimetre or two away, outside the leaf boundary layer.

Diversity and the Coevolution of Competitors, or the Ghost of Competition Past

Article

Oct 1980
OIKOS

Joseph H. Connell

That niches of competitors in ecological communities are shaped by mutual coevolution, which thus allows many species to coexist, is a commonly-held view. Two species must live together consistently to coevolve, so since predators (or parasites) are dependent upon their prey, they will necessarily co-occur with them and so should coevolve. In contrast, competing species, which are not dependent on each other, need not consistently co-occur or coevolve. Increased diversity, by reducing the consistency of co-occurrence, also reduces the chance of coevolution. To demonstrate coevolutionary divergence of competitors one must show: 1) that divergence has actually occurred: this has been done for some fossil sequences but not for any extant competitors; 2) that competition, rather than some other mechanism, is responsible; and 3) that it has a genetic basis. To demonstrate 2) and 3) for natural populations requires appropriate field experiments, which are suggested in the paper. This has been done, in part, in only one case. Thus the notion of coevolutionary shaping of competitors' niches has little support at present. Theory and evidence suggest that it is probable only in low diversity communities. /// То, что ниши конкурентов в экологических сообщаствах оформились в процессе коэволюции, поэволяющей т.о. сосуществовать многим видам, общепринятая точка зрения. Два вида должны сосуществовать, последовательно коэволюционируя, так что, по-скольку хищники (или паразиты) зависят от своих жертв, они должны непременно встречаться вместе и т.о. могут коэволюционировать. В противоположность этому, конкурирующие виды, независимые друг от друга, наобязательно должны встречаться вместе и коэволюционировать. Повышение разнообрязия при снижении постоянства совместной встречаемости таюже снижает возможность коэволюции. Для демонстрации коэволюционной дивергенции конкурентных видов следует показать: 1. что дивергенция реально существует; это было сделано для некоторых ископаемых рядов, но не для современных конкурирующих форм. 2. что конкуренция более реактивна, чем любой другой механизм; 3. и что она имеет генетическую основу. Чтобы доказать второй и третий пункты для естественных популяций, необходимо проведение полевых экспериментов, которые предложены в статье. Это было частично проделано лишь в одном случае. Таким образом, представление о формах коэволюции ниш конкурирующих видов плохо обосновано. Теория и имеющиеся факты говорят о том, что это возможно лишь для сообществ с низким разнообразием.

Dynamic plant ecology: The spectrum of vegetational change in space and time

Article

Jan 1983

Avian ecology: an iconoclastic view.

Chapter

Jan 1983

John Wiens

Supply side ecology: The role of physical transport processes

Chapter

Jan 1987

Spatial Aspects of Species Interactions: the Wedding of Models and Experiments

Chapter

Jan 1988

Ecological theory is in an obvious state of flux. Earlier attempts to model communities using equilibrium analyses of Lotka-Volterra equations have fallen into disfavor (see the volumes edited by Price et al. 1984, and by Diamond and Case 1986). Indeed, it seems that many experimental ecologists have given up on theory altogether — rather than testing models, field ecologists are now mostly concerned with proper experimental design and the detection of significant effects attributable to one manipulation or another. Theoreticians, of course, continue to develop models; but even among theoreticians there is no consensus about the sorts of models that most deserve our attention. While everyone may agree that we need to move beyond simple Lotka-Volterra equations, few can agree upon the ways in which models might be made more pertinent to the natural world. For example, in this volume alone, arguments are made for extending theory to include: age structure (Hastings), stochastic environments (Chesson), the effects of spatial scale (Levin), fluid dynamics (Okubo), and food web architecture (Cohen, Pimm, and Yodzis). Yet clearly no model can handle all of these complications at once. This leaves us with the problem of determining which theoretical elaborations are called for by different real-world systems, and how these theories might be applied to experimental studies.

Transmission of Variance through Lake Food Webs

Chapter

Jan 1987

Stephen R. Carpenter

Temporal variability is a hallmark of ecological communities. Variable species dynamics imply that certain limnological events will not be predictable (Edmondson 1979) and that the predictability of ecological systems may have inherent limits (Paine 1981). Because temporal variability impedes prediction, it is a source of frustration for ecologists and resource managers. However, there are hopeful signs that certain approaches to ecological variability may yield new insights about community organization and allow more successful management of natural resources. I offer three illustrations of this point.

The Influence of Food Supply on Local Density and Diversity of Sparrows

Article

Aug 1987

A long-term study of sparrows in an arid oak woodland in southeastern Arizona demonstrated that local population density of sparrows is independent of local seed abundance during years of moderate to high seed production. Experimental manipulation of the abundance and size distribution of seeds during 2 yr of moderate seed production had no discernible influence on the local abundance or diversity of sparrows. These experimental results support the hypothesis, based on previous nonexperimental observations, that sparrow populations in this habitat are locally food limited only during infrequent years of very low seed productions.

The Controversy Over Interspecific Competition

Article

Jan 1982

Thomas W. Schoener

Structure of fish communities of French Polynesia coral reefs. II. Temporal scales

Article

Dec 1987

R. Galzin

The Temporal Scale of Variance in Limnetic Primary Production

Article

Mar 1987

Substantial variability in the productivity of the world's lakes cannot be explained by methodology, weather, hydrology, or nutrient supply. A deterministic model shows that variable piscivory, cascading through the food web and causing fluctuations in planktivory, herbivory, and primary production, can bring about variability in primary production comparable in magnitude and time scale to the variability that cannot be explained by physical or chemical factors. The variance of productivity and the correlation between primary production and zooplankton biomass are functions of the time scale over which model results were averaged. The scatter of data around regressions of annual production versus nutrient loading represents internal system dynamics at a host of time scales, some of which may be regulated by fish populations. An important consequence of these dynamics is that variances and covariances of limnological variables are strongly related to sampling scale. Nutrient loading, hydrology, and spring ...

Statistical Theory of Groundwater Flow and Transport: Pore to Laboratory, Laboratory to Formation,and Formation to Regional Scale

Article

Aug 1986

Gedeon Dagan

The statistical approach has been applied increasingly to groundwater flow problems in the last decade. This development has been motivated by the recognition of the fact that porous formations are heterogeneous, i. e. , with properties which vary in an irregular manner in space. Flow domains are characterized by the length scale L of their spatial extent and three such scales of a fundamental nature are introduced: the laboratory, the local, and the regional scale. Heterogeneity is characterized by the spatial correlation scale I of the property of interest, the three scales corresponding to the above ones being the pore scale, the log hydraulic conductivity, and the log transmissivity integral scales. The main objective of the study is to show that flow and transport problems at the three fundamental scales can be treated by a unified statistical approach, along this line. The specific aspects of each scale are examined separately, and areas of interest for future research are indicated. In the concluding remarks it is submitted that the statistical approach to groundwater flow has become a comprehensive theory, beyond the stage of an ad hoc modeling technique.

Spatial Scaling in Ecology

Abstract

No full-text available

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