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Deviance information criterion (DIC) values for metapopulation models for five epiphytic lichen species, with the final model in boldface type.
Source publication
The colonization-extinction dynamics of many species are affected by the dynamics of their patches. For increasing our understanding of the metapopulation dynamics of sessile species confined to dynamic patches, we fitted a Bayesian incidence function model extended for dynamic landscapes to snapshot data on five epiphytic lichens among 2083 mapped...
Citations
... Tree hollows are a relatively long-lasting habitat compared with other types of dead wood. We hypothesised that it might take time for invertebrate fauna to colonise and occupy hollow trees due to limited dispersal ability, as has been found for epiphytes (Johansson, Ranius & Snäll, 2012). However, we found no support for time effects in the literature. ...
Tree hollows support a specialised species‐rich fauna. We review the habitat requirements of saproxylic (= deadwood dependent) invertebrates which occupy tree hollows. We focus on studies quantifying relationships between species occurrence patterns and characteristics of tree hollows, hollow trees, and the surrounding landscape. We also explore the processes influencing species occurrence patterns by reviewing studies on the spatio‐temporal dynamics of populations, including their dispersal and genetic structure. Our literature search in the database Scopus identified 52 relevant publications, all of which were studies from Europe. The dominant taxonomic group studied was beetles. Invertebrates in hollow trees were often more likely to be recorded in trees with characteristics reflecting a large amount of resources or a stable and warm microclimate, such as a large diameter, large amounts of wood mould (= loose material accumulated in the hollows mainly consisting of decaying wood), a high level of sun exposure, and with entrance holes that are large and either at a low or high height, and in dry hollows, with entrances not directed upwards. A stable microclimate is probably a key factor why some species of saproxylic invertebrates are confined to tree hollows. Other factors that are different in comparison to downed dead wood is the fact that hollows at a given height from the ground provide shelter from ground‐living predators, that hollows persist for longer, and that the content of nutrients might be enhanced by the accumulation of dead leaves, insect frass, and remains from dead insects. Several studies have identified a positive relationship between species occupancy per tree and the amount of habitat in the surrounding landscape, with a variation in the spatial scale at which characteristics of the surrounding landscape had the strongest effect over spatial scales from 200 to 3000 m. We found empirical support for the extinction threshold hypothesis, which predicts that the frequency of species presence per tree is greater if a certain number of trees are aggregated into a few large clusters of hollow trees rather than distributed among many small clusters. Observed thresholds in species occurrence patterns can be explained by colonisation–extinction dynamics, with species occupancy per tree influenced by variation in rates of immigration. Consistent with this assumption, field studies suggest that dispersal rate and range can be low for invertebrates occupying tree hollows, although higher in a warmer climate. For one species in which population dynamics has been studied over 25 years ( Osmoderma eremita ), the observed population dynamics have characteristics of a “habitat‐tracking metapopulation”, as local extinctions from trees occur possibly because those trees become unsuitable as well as due to stochastic processes in small populations. The persistence of invertebrate fauna confined to tree hollows may be improved by prolonging the standing life of existing hollow trees. It is also important to recruit new generations of hollow trees, preferably close to existing larger groups of hollow trees. Thus, the spatio‐temporal dynamics of hollow trees is crucial for the invertebrate fauna that rely upon them.
... Hence, the simple frequency of microhabitats may not bring any support for lichen communities while moderateand in the forest quite inconspicuousdifferences in microhabitat heterogeneity may deeply influence both species richness and composition of lichen communities. The importance of specific (micro)structures for epiphytic and epixylic lichen species, and especially those threatened, has been already documented in boreal and temperate forests (Fritz and Heilmann-Clausen, 2010;Johansson et al., 2012;Ranius et al., 2008). A novel finding of our study is the demonstration of a close correspondence between variability in compositions of microhabitats and lichen species communities at the regional scale. ...
... beech forests) are protected in small and mutually isolated forest reservations with areas of a few tens of hectares. Lichen species closely associated with specific microhabitats have little chance of sustaining viable populations, as specific microhabitats may simply disappear for a certain period from area-limited habitats (Johansson et al., 2012;Roberge et al., 2011). Low dispersal rate of lichens likely further exacerbates the negative effect of small and mutually isolated suitable habitats on lichen populations (Ellis, 2012). ...
Habitat loss, fragmentation and degradation are major causes of the ongoing decline of epiphytic and epixylic lichen species in temperate forests throughout Europe. We investigated how extant species richness and composition of epiphytic and epixylic lichen communities in ten hot-spots of lichen diversity in the Czech Republic reflected the occurrence and properties of potentially suitable microhabitats and habitats. At each hot-spot, we surveyed a pair of 1-ha square plots, one in (over-)mature managed and the second in unmanaged forest. In total, we recorded 513 epiphytic and epixylic lichen species which represent a substantial part of lichen biota in Central Europe. Species richness and composition of lichen communities were explained by microhabitat heterogeneity, and also by the area of near-natural forest habitats (habitat extent) at the landscape scale. In addition, lichen species richness and number of red-listed species were explained by a categorial variable distinguishing mature managed and unmanaged plots, used as a proxy of temporal continuity of natural succession. This finding illustrates that temporal continuity of natural succession in unmanaged forests likely had an extra stimulus for lichen communities that may not be reflected by observed aspects of forest habitats. Hence, we confirmed indispensable positive effects of (micro)habitat heterogeneity, and spatial and temporal continuity for preserved hot-spots of lichen diversity in Central Europe. Due to generally slow colonization-extinction dynamics of epiphytic and epixylic lichens we call for strengthening microhabitat heterogeneity, and the spatial and temporal continuity of European temperate forests at the landscape scale.
... Several metapopulation studies on terrestrial systems have proposed ways to include the existence of the background deposition (Johansson et al. 2012, Norros et al. 2012. Local colonization and background deposition in a limited study site. ...
Understanding the colonization process of species living in a dynamic fragmented habitat is essential to assess their persistence. In the metapopulation theory, the colonization of a species can be quantified using the turnover of occupancy in habitat patches. However, this approach is often limited by the feasible size of surveyed areas. Because many species are capable of long‐distance dispersal, such areas often constitute open systems undergoing colonization of propagules coming from outside, the ‘background deposition'. We focus on disentangling background deposition from local colonization among surveyed patches when analyzing turnover. We consider two spatial scales: 1) focal areas where all patches are monitored over time; 2) a larger extent, encompassing the focal areas, over which the distribution of the target species is quantified with a coarse spatial grain. Our key idea is to use the regional connectivity of focal areas within the larger scale as a covariate when analyzing colonization events within focal areas. A positive effect of regional connectivity on the colonization probability of patches may indicate background deposition. We applied this approach to the epiphytic bryophyte Dicranum viride in a managed temperate deciduous forest, considering phorophyte trees as patches, forest stands as focal areas and the whole forest as the larger scale. We combined a fine‐grained turnover survey of occupied trees within three forest stands (~ 3 ha) with a coarse‐grained snapshot of D. viride distribution over the forest (~ 15 000 ha). Regional connectivity came out as the most significant factor, with a strong positive effect on colonization probability within stands. However, it was attributed to sources in the immediate vicinity of focal stands, suggesting a short‐ranged colonization process occurring across stands' borders rather than long‐distance background deposition. Our results thus call for maintaining a stepping‐stone of habitat across the forest through time to improve D. viride persistence.
... Patch-dynamics models can capture spatial effects and help predict environmental effects (Leibold and Loeuille, 2015). For that reason, the patch-dynamics model is regarded as a 'useful tool in metapopulation viability analysis for comparing species persistence' (Johansson et al., 2012). Patch-dynamics models are more flexible than traditional models when used for similar purposes and can capture better the characteristics of populations, they deserve to be further explored. ...
Based on equilibrium assumptions, traditional ecological models have been widely applied in the fields of management and organization studies. While research using these models is still ongoing, studies have nonetheless struggled with ways to address multiple levels of analysis, uncertainty, and complexity in their analyses. This paper conceptualizes the dynamic co-evolution mechanisms that operate in an ecosystem across multiple organizational scales. Specifically, informed by recent advances in modelling in biology, a general ‘patch-dynamics’ framework that is theoretically and methodologically able to capture disequilibrium, uncertainty, disturbances, and changes in organizational populations or ecosystems, as complex and dynamically evolving resource environments are introduced. Simulation models are built to show the patch-dynamics framework’s functioning and test its robustness. The patch-dynamics framework and modelling methodology integrates equilibrium and disequilibrium perspectives, co-evolutions across multiple organization levels, uncertainties, and random disturbances into a single framework, opening new avenues for future research on topics in the field of management and organization studies, as well as on the mechanisms that shape ecosystems. Such a framework has the potential to help analyse the sustainability and healthiness of the business environment, and deserves more attention in future research on management and organization theory, particularly in the context of significant uncertainty and disturbances in business and management practice. Overall, the paper offers a distinct theoretical perspective and methodology for modelling population and ecosystem dynamics across different scales.
... Therefore, they often have a large distribution range and are found in a variety of habitats. Specialist species are closely associated with specific microhabitats (the smallest subunit of forest habitat like pieces of deadwood, rocks), with narrow ecological requirements and reduced dispersal abilities (During, 1992;Johansson et al., 2012). ...
... Liverworts are known to be more specialist species, closely associated with one or a few well-defined microhabitats, with narrow ecological requirements and reduced dispersal abilities (Caners et al., 2013a;Johansson et al., 2012). In our study, liverwort species richness was primarily explained by stands variables (hardwood and coniferous basal area). ...
... In cohort 1, liverwort species richness was secondly explained by microhabitat variables (deadwood volume, stumps, snags), which was consistent with the tight relationship of this group with its substrate (Caners et al., 2013a;Johansson et al., 2012). Liverworts commonly grow as epixylics on decayed wood in boreal forests and are sensitive to canopy removal (Arseneault et al., 2012;Fenton et al., 2003). ...
Sustainable forest management relies on a diversity of harvesting practices to conserve the variety of stand structures and compositions found in natural forests. Extensive use of clearcuts can homogenize stand structure by removing all the canopy, damage forest soils and destroy older downed woody debris already present within stands. In contrast partial cuts maintain some standing overstory and conserve certain biological legacies like large live trees as well as standing and downed dead wood, and thus should better conserve biodiversity. However, given the large number of species potentially affected by harvest operations, balancing harvesting intensity and conservation of biodiversity requires a clear understanding of habitat requirements of resident organisms and species conservation post-harvest. We examined the impacts of increasing intensities of stem removal (33%, 40%, 66% and 100%) 20 years after harvest on bryophyte communities in three stand types common in the succession sequences of Eastern boreal mixedwood forests that were dominated by trembling aspen, mixedwood and conifers. While many generalist and common forest species were shared among all harvesting levels and forest types, more specialized species like liverworts differed strongly between uncut and clearcut stands and less between uncut and partial cut stands. Bryophyte species in hardwood dominated stands tolerated more fluctuations in environmental conditions than species in mixed stands. We were unable to find habitat specialists typically associated with coniferous stands and may be related to prior outbreaks of spruce budworm that occurred 30 years ago. Our results highlight how harvest intensity and forest stand type interact to affect bryophytes and how intact stands may be required to conserve many species that are sensitive to any degree of harvesting.
... Cryptogamic organisms have a high colonizing ability due to the huge number of formed small diaspores and the wide range of their dispersal [4,5]. However, the success of colonization depends not only on the characteristics of diaspores (size, dispersal distance) and distance from their source [6], but also on the width of the ecological niche of species [7] and reproductive strategy, e.g. the predominant dispersal using generative or vegetative diaspores, which differ significantly in terms of survival [8]. ...
The dynamics of the species composition of mosses and lichens on the fir and spruce dead wood was studied in the southern taiga of the Middle Urals after the cessation of emissions from the copper smelter (Revda, Sverdlovsk region). Compared to the period of high emissions
(1993–1994), the number of moss species in the immediate vicinity of the plant (1–2 km) increased
from 1 to 27 by 2019, and the number of lichen species increased from 1 to 30. Nevertheless, the species richness
of mosses and lichens remains reduced compared to that of the background area, and the species
composition differed significantly: many species typical for the background area were absent, and species
specific to the disturbed area were present. In the polluted habitats, the proportion of species with predominantly
sexual reproduction was higher.
... Species may vary in their colonization and extinction rates, as well as whether they have stable metapopulation dynamics or are instead transiently present and expected to become extinct. Comparing metapopulation rates and dynamics across multiple species can be used to associate species' properties with their colonization and extinction rates (e.g., Johansson et al., 2012), to assess the consequences of the spread of introduced species on communities (Pointier & David, 2004;Svenning et al., 2014), to optimize conservation planning to decrease extinction risk for multiple species (Nicholson et al., 2006), and more generally to better inform current and expected biodiversity patterns. Our purpose here is to evaluate, using a case study, whether a metapopulation model can be used to generate accurate estimates of demographic parameters and to describe the diversity of dynamics, responses to environment, and prospects of long-term persistence in a guild of species inhabiting a common fragmented landscape. ...
Characterizing the diversity of demographic strategies among species can inform research in topics such as trait syndromes, community stability, coexistence, and ecological succession. However, this diversity can depend on the spatial scale considered: at the landscape scale, species often form metapopulations, that is sets of local, sometimes short‐lived, populations, inhabiting discrete habitat patches. Metapopulation dynamics are most frequently analyzed in individual species or pairs of interacting species because of the large amount of data required for multiple species, and because species vary in their perceptions of what constitutes a favorable or unfavorable habitat. Here we evaluate, using a case study, whether a metapopulation model can be used to generate accurate estimates of demographic parameters and to describe the diversity of dynamics, responses to environment, and prospects of long‐term persistence in a guild of species inhabiting a common fragmented landscape. We applied this approach to a guild of 22 mollusk species that inhabit freshwater habitats on two islands of Guadeloupe, to compare metapopulation dynamics among species. We analyzed a 15‐year time series of occupancy records for 278 sites using a multistate occupancy model that estimated colonization and extinction rates as a function of site‐specific and year‐specific environmental covariates, then used model results to simulate future island metapopulation dynamics. Despite the diverse array of metapopulation trajectories—a mix of species with either stable, increasing, declining, or fluctuating metapopulations—and the inherent challenges associated with such data (e.g., imperfect detection, spatial and temporal heterogeneity), our model accurately captured among‐patch variation in suitability for many mollusk taxa. The dynamics of rare species or species with habitat preferences not fully captured by the retained set of covariates were less well described. For several species, we detected a negative correlation between extinction and colonization. This variation in habitat suitability created species‐specific extinction‐resistant pockets in the landscape. Our comparative analysis also revealed that species had distinct strategies for metapopulation dynamics, such as “fast‐turnover” species with both a high proportion of occupied sites and a high rate of site extinction in the landscape.
... However, cumulative lichen diversity at a broader landscape scale likely coincides with habitat heterogeneity, which points to mixedseverity disturbance hypothesis Thom & Seidl, 2016). Long temporal continuity and high mutual connectivity of heterogeneous habitats can provide a more or less constant availability of specific and/or unique microhabitats across the landscape, such as large deadwood, as well as deadwood in various stages of decay (Ellis, 2012;Johansson et al., 2012). ...
... Natural disturbances appear to play an essential role in maintaining this biodiversity. To ensure the survival of lichen species with narrow habitat requirements, it is critical to ensure the continual persistence of forests in all developmental phases (Johansson et al., 2012). Downed logs and standing deadwood were inhabited by different lichen communities and are crucial for the survival of a number of lichens (Bunnell et al., 2008). ...
Aim
Natural disturbances influence forest structure, successional dynamics, and, consequently, the distribution of species through time and space. We quantified the long-term impacts of natural disturbances on lichen species richness and composition in primary mountain forests, with a particular focus on the occurrence of endangered species.
Location
Ten primary mountain spruce forest stands across five mountain chains of the Western Carpathians, a European hotspot of biodiversity.
Methods
Living trees, snags, and downed logs were surveyed for epiphytic and epixylic lichens in 57 plots. Using reconstructed disturbance history, we tested how lichen species richness and composition was affected by the current forest structure and disturbance regimes in the past 250 years. We also examined differences in community composition among discrete microhabitats.
Results
Dead standing trees as biological legacies of natural disturbances promoted lichen species richness and occurrence of threatened species at the plot scale, suggesting improved growing conditions for rare and common lichens during the early stages of recovery post-disturbance. However, high-severity disturbances compromised plot scale species richness. Both species richness and the number of old-growth specialists increased with time since disturbance (i.e. long-term uninterrupted succession). No lichen species was strictly dependent on live trees as a habitat, but numerous species showed specificity to logs, standing objects, or admixture of tree species.
Main conclusions
Lichen species richness was lower in regenerating, young, and uniform plots compared to overmature and recently disturbed areas. Natural forest dynamics and its legacies are critical to the diversity and species composition of lichens. Spatiotemporal consequences of natural dynamics require a sufficient area of protected forests for provisioning continual habitat variability at the landscape scale. Ongoing climatic changes may further accentuate this necessity. Hence, we highlighted the need to protect the last remaining primary forests to ensure the survival of regionally unique species pools of lichens.
... They are also the outcome of a complex evolutionary process involving the different symbiotic partners, and leading to a diversity of phenotypes that reflect, to varying degrees, adaptive radiation or convergent evolution, so providing the rich multivariate framework required to explore linkages between ecological fitness, environmental gradients and ecosystem function. Applying a trait-based approach to lichens has important practical benefits in conservation too; for example, it is the difference between a taxonomic list such as for lichen indicators observed to associate with ecological continuity [12][13][14][15], and understanding-with its increased confidence-the features of lichen biology that are mechanistically linked to old-growth conditions because of interactions with environmental constraints [16][17][18]. ...
Community ecology has experienced a major transition, from a focus on patterns in taxonomic composition, to revealing the processes underlying community assembly through the analysis of species functional traits. The power of the functional trait approach is its generality, predictive capacity such as with respect to environmental change, and, through linkage of response and effect traits, the synthesis of community assembly with ecosystem function and services. Lichens are a potentially rich source of information about how traits govern community structure and function, thereby creating opportunity to better integrate lichens into ‘mainstream’ ecological studies, while lichen ecology and conservation can also benefit from using the trait approach as an investigative tool. This paper brings together a range of author perspectives to review the use of traits in lichenology, particularly with respect to European ecosystems from the Mediterranean to the Arctic-Alpine. It emphasizes the types of traits that lichenologists have used in their studies, both response and effect, the bundling of traits towards the evolution of life-history strategies, and the critical importance of scale (both spatial and temporal) in functional trait ecology.
... Thus, metapopulation and metacommunity theory have been applied successfully to analyse the dynamics of epiphyte populations (e.g. Johansson et al., 2012;Laube & Zotz, 2007;Snäll et al., 2003) and communities (e.g. Burns, 2007;Einzmann & Zotz, 2017;Löbel & Rydin, 2009). ...
Despite the ecological importance of vascular epiphytes in the tropics, even basic information on the processes that form epiphyte communities is scarce. This is partially due to an almost complete lack of long‐term studies.
Here, we present data that were collected in three consecutive censuses over 21 years in a monospecific host tree system that is about 100 years old and interpret them in an empirical and a metapopulation/metacommunity framework.
We documented an ongoing increase in abundance and diversity at the level of the entire system (metacommunity) and at the level of communities (all epiphytes growing on individual Annona glabra tree stands). This was also reflected at the population level; >2/3 of the species showed positive population growth rates. Similarly, colonisation of empty Annona trees was still ongoing, with the most abundant species being also the first to colonise empty trees. The community composition of colonised trees became more similar with time. In all three censuses, habitat size of epiphytes explained much of the variation in species richness among stands (groups of trees with individual trees within 25 m of each other) and overall abundant species tended to be more abundant at the stand scale. The species frequency distribution was unimodal, regardless of whether considering all stands or only stands with very large epiphyte communities, indicating that the metacommunity still has not reached an equilibrium phase. Similarly consistent in both census intervals, population growth rates decreased with increasing population size with substantial asynchrony among populations.
Synthesis. In contrast to a typical herbaceous plant community, this epiphyte metacommunity is still expanding after one century of development. Our study shows that previously reported short‐term patterns of epiphyte community dynamics hold true in the long term. It remains to be shown, however, whether results from this monospecific host tree system are really representative for epiphyte community dynamics in more diverse tropical forests.
