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High Productivity in Grassland Ecosystems: Effected by Species Diversity or Productive Species?
... We recorded and identified all vascular plants in each plot during the survey period. In the subsequent analyses, we divided the plant species into annual and perennial plants because the plant growth rate is dependent on these life-history traits (Aarssen, 1997). We also collected soil samples (approx. ...
... Although species with high regeneration rates (i.e., annual plant species) may recolonize during the early successional stage after massive disturbances (cf. Aarssen, 1997), the present study showed that many perennial and woody plants recovered in the disturbance legacy areas. These results suggest that plant tissues and roots were deposited in areas with large wood after a massive disturbance, increasing the ecosystem's resilience. ...
... This phenomenon may be explained by annual plants regenerating under frequent disturbances from running water in the open habitat sites (cf. Grime, 1974, Aarssen, 1997. ...
Understanding biodiversity resilience after a major disturbance is a key issue in basic and applied science. Plant diversity in gravel-bed rivers is affected by flood events, which are one of the most effective disturbance agents in the flow regime, affecting species distribution, and ecosystem dynamics. Although disturbance plays a critical role in community assembly mechanisms, how plant diversity recovers after a severe disturbance, such as a 100-year flood event remains unknown. The present study examined how the disturbance legacy of large wood in gravel-bed river ecosystems contributes to the resilience of plant diversity. The present study demonstrated that the resilience of plant species in disturbance legacy sites, namely deposited large wood sites, was higher than that in open habitat sites. Indicator species analysis revealed that perennial plants were the most important indicator species of disturbance legacy sites. These results suggest that perennial species richness contributes to the resilience of high plant diversity across the disturbance legacy sites in this region. After major flood events, land managers often remove large wood and debris jams to avoid secondary disasters, such as embankment collapse. However, we suggest that large wood should be retained on the gravel beds to aid the recovery of biodiversity and ecosystems. Furthermore, understanding the relationships between disturbance legacies and ecosystem resilience can contribute to the formulation of strategies for sustainable ecosystem management and biodiversity conservation in the future.
... Overall, the relationships between biodiversity and ecosystems function (i.e., carbon pool and aboveground biomass) is well documented under the two ecological hypotheses; niche complementarity (also known as facilitation, Aarssen, 1997;Fornara and Tilman, 2008;Walter, 1991) and mass ratio (also known as selection effects; Grime, 1978;Conti and Díaz, 2013). According to the niche complementarity hypothesis, diverse communities have more functioning (i.e., biomass production) due to greater capturing of available resources (Finke and Snyder, 2008) and more chance to include different strategies of resource utilization and lesser competition among species (Mensah et al., 2018). ...
... On the other hand, mass ratio hypothesis links ecosystems function to the functional characteristics of dominant species and states that the higher functioning of ecosystems may result from the greater value of dominant species (Reich et al., 2001). Additionally, increase chance of random sampling of highly productive species (also known as sampling effects) can also lead to increased ecosystems functioning with increasing diversity (Aarssen, 1997;Huston, 1979;. ...
... Generally, dissimilarity among local community composition may affect several ecological interactions such as organism's movement and resources that are essential for ecosystems functions (Hautier et al., 2018;Tscharntke et al., 2005). Compared to the many studies that quantify BEF relationship (i.e., Aarssen, 1997;Yachi and Loreau, 1999;Spehn et al., 2000;Maestre et al., 2012;Tredennick et al., 2017), relatively few studies have addressed how β diversity may relate to Fig. 1. Schematic diagram of possible relationships between β diversity (negative, positive, and neutral) components include A) Nestedness (due to species gain and species loss) and B) Turnover (due to species replacement) and ecosystems productivity. ...
There is consensus that greater biodiversity is essential to maintain the ecosystem function and stability. Variation in spatial plant community heterogeneity (β diversity) affects productivity and ecosystems function; however, relatively few studies have addressed how β diversity and its components (i.e. species turnover and nestedness) may relate to ecosystems function. In this study, we assessed plant community diversity (richness and evenness) and spatial heterogeneity along a productivity gradient in different bioclimatic regions including desert-steppe, steppe, semi-steppe and Mediterranean rangelands in south west of Iran, and tested (1): how and to what extent the different components of plant diversity affect aboveground biomass (AGB; as ecosystem productivity) and (2): the mechanisms underlying the relationship between β diversity and ecosystem productivity; i.e. niche complementary and selection effects. Sampling was executed in each bioclimatic region by choosing eight sites and estimating AGB of plant species in 2 × 2 m plots nested within 3 macro plots of 30 × 30 m.
The results showed that AGB was significantly predicted by species richness; positively in desert-steppe, steppe and semi-steppe rangelands and negatively in Mediterranean rangeland. Furthermore, AGB was negatively predicted by evenness in desert-steppe and semi-steppe rangelands. There were significantly negative relationships between β diversity and AGB in desert-steppe, steppe and semi-steppe rangelands, while, the significantly positive relationship was found for Mediterranean rangeland. The AGB was significantly and positively related to the turnover and nestedness components of β diversity in Mediterranean rangeland. However, a negative relationship was found with turnover in desert-steppe and semi-steppe rangelands.
Our results indicate that niche complementarity may play a critical role in providing and provision ecosystems productivity in steppe and Mediterranean rangelands, while, both selection effects and niche complementarity hypotheses could be verified in low-productive regions (desert-steppe and semi-steppe rangelands). Comparing the strength of species diversity with β diversity in predicting ecosystems productivity across different bioclimatic regions, our results revealed that β diversity predict ecosystems productivity more effectively and provide support for biodiversity-ecosystems function theories.
... The diversity hypothesis, favoured by early BEF studies, postulates greater production by more diverse communities because of complementarity between taxa or functional types (i.e., greater niche partitioning and facilitation; Tilman, 1999). By contrast, the mass-ratio hypothesis postulates that it is mainly the functional traits of dominant species that matter; consequently, ecosystems in which more efficient species are selected and dominate will be most productive on average (selection effect, Aarssen, 1997;Huston, 1997). ...
... This observation supports the mass-ratio (selection effect) hypothesis (Aarssen, 1997;Huston, 1997), implicating the functional traits of the dominant species as most directly influencing ecosystem functioning of the zooplankton community of boreal lakes. We found no support for any effect of complementarity (diversity hypothesis) that might indicate increases in niche partitioning or facilitation with diversity (Tilman, 1999) as no significant relations with ZooProd were observed for diversity indices unrelated to dominance (evenness) in the final SEM. ...
Although there is a general consensus in ecology that more diverse communities tend to be more productive, it is still unclear whether this holds for aquatic ecosystems, especially with indicators of productivity rates and not just standing biomass proxies. Furthermore, most evidence is based on the results of experimental studies in which biodiversity was assessed through taxonomic richness, although functional indicators could be more relevant.
Consequently, we still have a poor understanding of how real community performance is linked to the various features of community structure in natural aquatic ecosystems. Here we explicitly assessed the effect of functional traits and diversity on crustacean zooplankton productivity rates measured across 84 boreal Canadian lakes spanning wide limnological gradients. Productivity was assessed using the chitobiase enzyme method. Redundancy analyses and structured equation modelling were used to assess the relationship between zooplankton production rates, community structure (diversity and functional composition), while accounting for standing biomass and environmental factors
After controlling for the effect of environmental factors, zooplankton production rates were positively linked to dominance (lower functional evenness) by certain feeding traits ( Daphnia filtration and Chydorus filtration), demonstrating an identity (selection) effect.
Overall, the magnitude of the functional compositional effect on production was comparable to the aggregate effect of the environmental variables. Our study demonstrates that zooplankton functional community structure plays an important role in the regulation of a pivotal lake ecosystem function.
... The effect of species diversity on the productivity of a community has been explained by two mechanisms. They are: (i) the sampling effects, which state that the probability of finding key-trait species in a community is reduced due to lower species richness (Aarssen, 1997;Huston, 1997;Tilman et al., 1997) and (ii) the niche complementarity hypothesis, which states that less diverse communities with competing species utilize resources incompletely (Naeem et al., 1994;Tilman et al., 1996;Hector et al., 1999). Furthermore, the loss of interactive competition and loss of species diversity have been shown to increase mutualism, predation, herbivory, and infectious disease transmission (Bond, 1993;McNaughton, 1994;Chapin et al., 1997;Chapin et al., 2000). ...
... Several studies have previously suggested that this hypothesis applies only to a small number of plant species and genotypes (Garrett and Mundt, 1999;Zhu et al., 2000). The relaxed interspecific competition due to the decreased plant species richness has been shown to increase the abundance of one or more species existing in a local community, which typically also increases the abundance of one or more host species for specialist pathogens (Aarssen, 1997;Huston, 1997;Tilman et al., 1997). The basic mechanism of the diversitydisease hypothesis is that a decreasing number of plant species allows for an increased local abundance of other singular species, which then facilitates the spread of diseases specific to that species within the community (Burdon and Chilvers, 1976;Knops et al., 1999;Chapin et al., 2000). ...
Grasslands are major primary producers and function as major components of important watersheds. Although a concise definition of grasslands cannot be given using a physiognomic or structural approach, grasslands can be described as vegetation communities experiencing periodical droughts and with canopies dominated by grasses and grass-like plants. Grasslands have a cosmopolitan distribution except for the Antarctic region. Fungal interactions with grasses can be pathogenic or symbiotic. Herbivorous mammals, insects, other grassland animals, and fungal pathogens are known to play important roles in maintaining the biomass and biodiversity of grasslands. Although most pathogenicity studies on the members of Poaceae have been focused on economically important crops, the plant-fungal pathogenic interactions involved can extend to the full range of ecological circumstances that exist in nature. Hence, it is important to delineate the fungal pathogen communities and their interactions in man-made monoculture systems and highly diverse natural ecosystems. A better understanding of the key fungal players can be achieved by combining modern techniques such as next-generation sequencing (NGS) together with studies involving classic phytopathology, taxonomy, and phylogeny. It is of utmost importance to develop experimental designs that account for the ecological complexity of the relationships between grasses and fungi, both above and below ground. In grasslands, loss in species diversity increases interactions such as herbivory, mutualism, predation or infectious disease transmission. Host species density and the presence of heterospecific host species, also affect the disease dynamics in grasslands. Many studies have shown that lower species diversity increases the severity as well as the transmission rate of fungal diseases. Moreover, communities that were once highly diverse but have experienced decreased species richness and dominancy have also shown higher pathogenicity load due to the relaxed competition, although this effect is lower in natural communities. This review addresses the taxonomy, phylogeny, and ecology of grassland fungal pathogens and their interactions in grassland ecosystems.
... Moreover richness of species extensively helps us to extrapolate the variability between local level (alpha diversity), augmentation of biological habitats (Beta diversity) and variability of landscapes (Gamma diversity). In contrast, the ecological succession is mainly reliant on human and animal intervention; it includes all living things or biological resources and their essential components to maintain the existing or paradoxical changes of floristic diversity [4][5][6][7]. Now days due to industrialization, political and human intervention, small area ecosystems shows significant degradation, which can accelerate negative impact on Biological system and ecological balance (MoFR, 2019). ...
... More productive approaches to the environment will have more success in slowing forest habitat and biodiversity loss in the near future than reactive approaches The scenario most concerned with security protection has the highest rate of biodiversity loss. In pragmatic approach developing countries will experience an expansion of their agricultural lands and a reduction of their species richness [6]. Although the reverse is expected to happen in Industrial countries the result will be net loss of forest. ...
All living organisms are required to keep the ecosystem alive. One organism cannot exist without other organisms. Biodiversity is important for survival of the human and preserves the ecosystem. Hence biodiversity is called as 'balance of nature'. It is a hidden treasure that enriches all our lives. Undoubtedly the humans and animals survivability is mainly relying on the ecosystem niche. Indeed, with life support, biodiversity is the diverse range of organisms inhabiting their lives equally in our green planet. Now-a-days due to rapid urbanization, industrialization, modernization and vague policy and planning is drastically affected the biodiversity system, which can accelerate negative impact on quality of life (QOL) of all living organisms. All educational Institutions in India is forefront of fixed biodiversity and vital habitats, due to horizontal and vertical expansion of vegetation area for the purpose of creation of human settlement, construction of roads and bonafide of Government land to some other purposes is inevitability shows habitat loss, which is the largest factor contributing to the current national and global extinction events. Asper the past literature, Institutional biodiversity is alarming stage at national as well as global level; everybody should extend their helping hands to conserve the existing plant and animal species for the benefit of human health concern. In broad perspective ecosystem restoration in small area (Institutional biodiversity) is uniquely valuable tool for environmentalist, policy makers and forest officials for implementation of new policy to improve biodiversity at selected sites of various educational Institutions (smaller area). As long as, the estimation of biodiversity at Institutional level is recursive factor to predict how much vegetation area would be affected by biotic and A-biotic factors. In this proximity, the present study aims to estimate the species richness and floristic diversity at selected sites of KVAFSU regional campus. An observational survey-based study was conducted in the year 2014-2020 in accordance with standard operating procedure (SOP). Scientifically, the sample measuring was done in a 20 × 20 plot that was made and recorded as an individual species that are present in the demarcated boundary. The cluster sampling method was used to extrapolate the species composition and evenness. As per the research findings, a total 414 (13.66%) [Odds 0.987, p<0.05; 95% CI 10.25-26.38] tree species with 13 family, 8 genera; 10 herb species; 3 family 2 genera and 16 shrubs species besides with 4 family 3 genera was recorded during study period. Suboptimal biodiversity (unusable land) shield with geographical area of 356 acres of land. The human intervention or anthropogenic factor is greatly affected the biodiversity and it was found to be statistically significant (35.0%) [CI-95% 12.55-41.22; Odds 5.22 p=0.0022] followed by pollution (25%) [95% CI 10.68-28.79; Odd 6.31 p=0.0022]; drastic climatic changes (20%) [95% CI 8.63-25.18; odds 3.18 p=0.0016]; habitat degradations (8.0%) [95% CI: 3.16-10.74 p=0.0008]; Odds 4.86; invasive species (10%) [95% CI: 6.32-12.55; Odds 5.02 p=0.0012]; disease outbreaks (1.0%) [95% CI: 0.32-1.5% Odd 0.96 p=0.4123] etc. The following rare bird species were enlisted during the study period viz Forest owlet-05 (11.
... In the final section of this review, we pay particular attention to differences among studies in "species filters" or sampling processes invoked for community assembly. We believe that attention to these differences can partly resolve controversies in the literature about the relationship between biodiversity and ecosystem functioning (Aarssen 1997;Huston 1997;Tilman 1997;Grime 1998;van der Heijden et al. 1999;Wardle 1999). Experimental studies usually use arbitrary combinations of species simulating different-sized local species pools as their diversity treatment whereas observational studies mostly use the actual species number as their diversity variable. ...
... This "no-complementarityno-dominance process" corresponds to a situation described by Aarssen (1983) as competitive combining ability. The "sampling process" (Aarssen 1997;Huston 1997;Tilman 1997) differs from the nocomplementarity-no-dominance process in that high productivity of species assemblages is explained by the more likely occurrence of a highly productive species (Fig. 6.2b II). In the purest form of the sampling process, all assemblages will become monocultures of their highest-performing species. ...
... Structural equation modelling (SEM) was used to examine the effects of species richness, soil nutrients (C, N and P), stand density and forest types on fine root biomass in each soil layer with the "lavaan" package (Rosseel 2012). To account for potential selection effects (Aarssen 1997), we tested the role of the presence/absence of several tree species that were frequently present in the plots by introducing these species as covariates in the model. The "interact_plot" function from the package "jtools" version 1.1.1 ...
... The effect of the presence/absence of C. glauca on the positive diversity-function relationship is consistent with the "selection effect." The selection hypothesis postulates that high production in species rich communities could be due to the higher chance of there being a more productive species (Aarssen 1997). However, since naturally assembled forests are extremely complex and lack monocultures, we cannot fully explore the selection effect and can only conclude that the selection effect may exist in these Accepted Ar ticle 'This article is protected by copyright. ...
The importance of species richness to ecosystem functioning and services is a central tenet of biological conservation. However, most of our theory and mechanistic understanding is based on diversity found aboveground. Our study sought to better understand the relationship between diversity and belowground function by studying root biomass across a plant diversity gradient. We collected soil cores from 91 plots with between 1 to 12 aboveground tree species in three natural secondary forests to measure fine root (≤ 2 mm in diameter) biomass. Molecular methods were used to identify the tree species of fine roots and to estimate fine root biomass for each species. This study tested whether the spatial root partitioning (species differ by belowground territory) and symmetric growth (the capacity to colonize nutrient‐rich hotspots) underpin the relationship between aboveground species richness and fine root biomass. All species preferred to grow in nutrient‐rich areas and symmetric growth could explain the positive relationship between aboveground species richness and fine root biomass. However, symmetric growth only appeared in the nutrient‐rich upper soil layer (0–10 cm). Structural equation modelling indicated that aboveground species richness and stand density significantly affected fine root biomass. Specifically, fine root biomass depended on the interaction between aboveground species richness and stand density, with fine root biomass increasing with species richness at lower stand density, but not at higher stand density. Overall, evidence for spatial (i.e. vertical) root partitioning was inconsistent; assumingly any roots growing into deeper unexplored soil layers were not sufficient contributors to the positive diversity‐function relationship. Alternatively, density‐dependent biotic interactions affecting tree recruitment are an important driver affecting productivity in diverse subtropical forests but the usual root distribution patterns in line with the spatial root partitioning hypothesis are unrealistic in contexts where soil nutrients are heterogeneously distributed.
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... Previous BEF research has also raised new questions about the generality of mechanisms behind BEF relationships (Tilman et al., 2014;Weisser et al., 2017), specifically how different aspects of biodiversity (e.g., species, functional, and phylogenetic diversity) influence ecosystem functioning (Flynn et al., 2011) and the role of abiotic factors (e.g., drought, etc.) (Craven et al., 2016). BEF researchers have made an effort to demonstrate that the findings from controlled diversity experiments apply to real-world ecosystems and are generalizable across different types of ecosystems in response to criticism (Aarssen, 1997;Huston, 1997). BEF research has expanded into habitats other than grasslands during the last two decades, including farm fields, woods, lakes, streams, and marine environments. ...
... The reduced presence of volunteer species in mixtures can be a side effect of enhanced niche competitiveness and consequent soil resource depletion, termed "resource use complementarity" (Knops et al. 1999;Naeem et al. 2000). A secondary explanation attributed to this reduction is the "sampling effect", which is illustrated by the larger probably that at least one of the selected species will be at the peak of competitiveness, therefore Journal of New Zealand Grasslands 85: 309-320 (2023) reducing chances of non-desired species succession (Aarsen 1997;Huston 1997). Another study suggests that both processes may occur concomitantly in diverse pastures (Tracy and Sanderson 2004), which may be the case in the current study. ...
... Therefore, we here use the terms selection probability effect and complementarity effect in a broader, more conceptual sense (Fig 1, Box 1). We use the term selection probability effect (sensu Aarssen 1997) to refer to the case in which the functioning of a system is predominantly driven by one (or few) of its components. Conversely, we use the term complementarity effect to refer to the case in which all (or many) of the components of a system contribute to its functioning. ...
Numerous biodiversity–ecosystem functioning (BEF) experiments have shown that plant community productivity typically increases with species diversity. In these studies, diversity is generally quantified using metrics of taxonomic, phylogenetic, or functional differences among community members. Research has also shown that the relationships between species diversity and functioning depends on the spatial scale considered, primarily because larger areas may contain different ecosystem types and span gradients in environmental conditions, which result in a turnover of the species set present locally. A fact that has received little attention, however, is that ecological systems are hierarchically structured, from genes to individuals to communities to entire landscapes, and that additional biological variation occurs at levels of organization above and below those typically considered in BEF research. Here, we present cases of diversity effects at different hierarchical levels of organization and compare these to the species‐diversity effects traditionally studied. We argue that when this evidence is combined across levels, a general framework emerges that allows the transfer of insights and concepts between traditionally disparate disciplines. Such a framework presents an important step towards a better understanding of the functional importance of diversity in complex, real‐world systems.
... The reduced presence of volunteer species in mixtures can be a side effect of enhanced niche competitiveness and consequent soil resource depletion, termed "resource use complementarity" (Knops et al. 1999;Naeem et al. 2000). A secondary explanation attributed to this reduction is the "sampling effect", which is illustrated by the larger probably that at least one of the selected species will be at the peak of competitiveness, therefore Journal of New Zealand Grasslands 85: 309-320 (2023) reducing chances of non-desired species succession (Aarsen 1997;Huston 1997). Another study suggests that both processes may occur concomitantly in diverse pastures (Tracy and Sanderson 2004), which may be the case in the current study. ...
Diverse pastures of complementary species (DPCS) comprise species that fulfil different agroecological niches, resulting in growth asynchrony and complementarity of functional roles. It is expected that DPCS have a greater capability to tolerate and performunder increasingly extreme climate events, providing a potential alternative for New Zealand pastoral systems. In the present study, DPCS comprised Lolium perenne L., Bromus valdivianus Phil., Dactylis glomerata L., and Trifolium repens L. The leaf regrowth stage [LS; L. perenne (2.5-3.0LS), B. valdivianus (3.5-4.0LS) and D. glomerata (3.5-4.0LS)] is proposed to be an applicable method of defoliation management for DPCS due to a potential overlapping of the defoliation interval. The seasonal and annual herbage mass accumulation and botanical composition of DPCS and their respective single-grass and T. repens pastures under the LS criterion were assessed. The annual yield did not differ among pastures (average 20.26 t dry matter (DM) ha- 1). However, significant differences were found within seasons, with DPCS exhibiting asynchronous growth among species that reduced the seasonality of herbageaccumulation and invasion by volunteer species. Lolium perenne, B. valdivianus and D. glomerata were shown to be complementary grass species, presenting growth asynchrony and an overlapping defoliation interval that optimised production, indicating that defoliation based on LS criterion is a suitable management for DPCS.
... The mechanistic diallel analysis aimed to identify the contributions of individual strains, and strain combinations to the functioning of the mixtures. One mechanism that may lead to higher levels of functioning in more diverse communities is the selection probability effect (Aarssen, 1997). Essentially, if a few strains dominate the functioning of communities, then the more diverse mixtures will have a higher statistical probability of containing these strains, and the functioning of these mixtures will then be driven primarily by these dominant strains. ...
... Primary productivity is the fixation of carbon via photosynthesis and can be measured though oxygen production and related chemical fluxes (Bracken & Williams, 2013). Primary productivity has been strongly associated with the functional traits of dominant species (Bruno et al., 2006;Mouillot et al., 2011), raising the possibility that the association between biodiversity and productivity is predominantly an effect of these abundant, functionally unique species being included more frequently in more biodiverse samples (i.e., sampling effect; Aarssen, 1997;Huston, 1997). ...
Human impacts on ecosystems are resulting in unprecedented rates of biodiversity loss worldwide. The loss of species results in the loss of the multiple roles that each species plays or functions (i.e., “ecosystem multifunctionality”) that it provides. A more comprehensive understanding of the effects of species on ecosystem multifunctionality is necessary for assessing the ecological impacts of species loss. We studied the effects of two dominant intertidal species, a primary producer (the seaweed Neorhodomela oregona ) and a consumer (the shellfish Mytilus trossulus ), on 12 ecosystem functions in a coastal ecosystem, both in undisturbed tide pools and following the removal of the dominant producer. We modified analytical methods used in biodiversity–multifunctionality studies to investigate the potential effects of individual dominant species on ecosystem function. The effects of the two dominant species from different trophic levels tended to differ in directionality (+/−) consistently (92% of the time) across the 12 individual functions considered. Using averaging and multiple threshold approaches, we found that the dominant consumer—but not the dominant producer—was associated with ecosystem multifunctionality. Additionally, the relationship between abundance and multifunctionality differed depending on whether the dominant producer was present, with a negative relationship between the dominant consumer and ecosystem function with the dominant producer present compared to a non‐significant, positive trend where the producer had been removed. Our findings suggest that interactions among dominant species can drive ecosystem function. The results of this study highlight the utility of methods previously used in biodiversity‐focused research for studying functional contributions of individual species, as well as the importance of species abundance and identity in driving ecosystem multifunctionality, in the context of species loss.
... Trait differences between natives and non-natives might also influence the selective responses of each to variation in the surrounding biotic community; for example, non-native species that emerge rapidly (i.e., the phenotypic distribution is shifted earlier) may experience selection on seedling traits that is less sensitive to neighbor identity as even relatively late emerging individuals emerge earlier than the surrounding community. More taxonomically diverse communities can be characterized by more complete resource uptake via sampling and/or complementarity effects (Aarssen, 1997;Anten & Hirose, 1999;Guderle et al., 2017;Tilman et al., 1997;Wacker et al., 2009), which might lead to stronger selection exerted by communities with high versus low species diversity. Supporting this, a long-term biodiversity experiment found that plant populations from mixed-species communities evolved greater niche differentiation compared to populations from monocultures (van Moorsel et al., 2018a;Zuppinger-Dingley et al., 2014). ...
Plants interact extensively with their neighbors, but the evolutionary consequences of variation in neighbor identity are not well understood. Seedling traits are likely to experience selection that depends on the identity of neighbors because they influence competitive outcomes. To explore this, we evaluated selection on seed mass and emergence time in two California grasses, the native perennial Stipa pulchra and the non-native annual Bromus diandrus, in the field with six other native and non-native neighbor grasses in single and mixed species treatments. We also quantified characteristics of each neighbor treatment to further investigate factors influencing their effects on fitness and phenotypic selection. Selection favored larger seeds in both focal species and this was largely independent of neighbor identity. Selection generally favored earlier emergence in both focal species, but neighbor identity influenced the strength and direction of selection on emergence time in S. pulchra but not B. diandrus. Greater light interception, higher soil moisture, and greater productivity of neighbors was associated with more intense selection for earlier emergence and larger seeds. Our findings suggest that changes in plant community composition can alter patterns of selection in seedling traits, and that these effects can be associated with measurable characteristics of the community.
... Two basic patterns of species contributions to community productivity can be distinguished (Box 1). The selection probability effect (Aarssen 1997) occurs when the mixed community is dominated by a single species, typically the one that is most productive in monoculture. This effect generally occurs at the expense of the subordinate species. ...
Numerous biodiversity–ecosystem functioning (BEF) experiments have shown that plant community productivity typically increases with species diversity. In these studies, diversity is generally quantified using metrics of taxonomic, phylogenetic, or functional differences among community members. Research has also shown that the relationships between species diversity and functioning depends on the spatial scale considered, primarily because larger areas may contain different ecosystem types and span gradients in environmental conditions, which result in a turnover of the species set present locally. A fact that has received little attention, however, is that ecological systems are hierarchically structured, from genes to individuals to communities to entire landscapes, and that additional biological variation occurs at levels of organization above and below those typically considered in BEF research. Here, we present cases of diversity effects at different hierarchical levels of organization and compare these to the species-diversity effects traditionally studied. We argue that when this evidence is combined across levels, a general framework emerges that allows the transfer of insights and concepts between traditionally disparate disciplines. Such a framework presents an important step towards a better understanding of the functional importance of diversity in complex, real-world systems.
... Early critics of BEF research (for example, Aarssen 1997, Huston 1997, Huston et al. 2000, and Huston and McBride 2002 also questioned whether the experimental data truly isolated species richness as a causal factor that operates independently of species composition. In reacting to this challenge, BEF scientists did not see a need to change any essential design element of their experiments. ...
The idea of conserving biodiversity has become central to the very meaning of biological conservation---in the public imagination and for conservation organizations worldwide. Identification of conservation with biodiversity conservation owes extensively to the idea that warrant for biodiversity's conservation is anchored in the empirical thesis that biodiversity causally determines ecosystem functioning, and thereby, somehow, important ecosystem services. This idea has fueled an enormous research program dedicated to producing the requisite causal evidence. This essay first reviews the data that are supposed to constitute direct evidence for biodiversity's causal influence. It proceeds by answering a heretofore unasked, yet foundational, question for causal hypotheses: Do these data meet basic requirements for credibility as causal evidence? By virtue of mistakenly reading causal significance into (i) massive numbers of causally irrelevant data points, (ii) an equation that simply equates a stipulated definition to an algebraically equivalent expression, and (iii) correlations produced by arbitrary computations over previously collected data sets, these data fall well short of meeting these requirements. Mistakes also suffuse the notion that biodiversity's supposed causal influence gives reasons to conserve it. These mistakes are exposed when the conservation argument that was supposed to proceed from the premise of biodiversity's causal influence is clearly spelled out. Once made explicit, each step is seen to rely on a questionable assumption, invalid logic, or both. The essay concludes with implications for conservation, biodiversity research, and scientific inquiry more generally.
... Higher productivity of mixtures can be explained by selection and complementarity effects (Cardinale et al., 2007;Fargione et al., 2007;Marquard et al., 2009;Roscher et al., 2007). Positive selection effects emerge from a single or a few highly productive plant species with a disproportionally large effect on community biomass production and the increasing probability for the occurrence of such species in communities with higher species richness (Aarssen, 1997;Huston, 1997). Positive complementarity effects can be induced by niche partitioning or mutualistic interactions, which decrease interspecific competition and thus enhance community biomass production (Loreau & Hector, 2001). ...
Positive plant diversity-productivity relationships are known to be driven by complementary resource use via differences in plant functional traits. Moreover, soil properties related to nutrient availability were shown to change with plant diversity over time; however, it is not well-understood whether and how such plant diversity-dependent soil changes and associated changes in functional traits contribute to positive diversity-productivity relationships in the long run. To test this, we investigated plant communities of different species richness (1, 2, 6, and 9 species) in a 15-year-old grassland biodiversity experiment. We determined community biomass production and biodiversity effects (net biodiversity [NEs], complementarity [CEs], and selection effects [SEs]), as well as community means of plant functional traits and soil properties. First, we tested how these variables changed along the plant diversity gradient and were related to each other. Then, we tested for direct and indirect effects of plant and soil variables influencing community biomass production and biodiversity effects. Community biomass production, NEs, CEs, SEs, plant height, root length density (RLD), and all soil property variables changed with plant diversity and the presence of the dominant grass species Arrhenatherum elatius (increase except for soil pH, which decreased). Plant height and RLD for plant functional traits, and soil pH and organic carbon concentration for soil properties, were the variables with the strongest influence on biomass production and biodiversity effects. Our results suggest that plant species richness and the presence of the dominant species, A. elatius, cause soil organic carbon to increase and soil pH to decrease over time, which increases nutrient availability favoring species with tall growth and dense root systems, resulting in higher biomass production in species-rich communities. Here, we present an additional process that contributes to the strengthening positive diversity-productivity relationship, which may play a role alongside the widespread plant functional trait-based explanation.
... The complementary effects hypothesis links tree species diversity and stand productivity to explain the advantages of mixed stands over monocultures (Aarssen 1997;Loreau 2000;Steckel et al. 2019;Van de Peer et al. 2018). According to this hypothesis, mixed forests with varying leaf areas, canopy heights and growth rates can obtain and utilize resources more effectively, thus improving stand productivity (Tilman et al. 1997). ...
Adapting forests to climate change is a critical issue for forest management. It requires an understanding of climate effects on forest systems and the ability to forecast how these effects may change over time. We used Spanish Second National Forest Inventory data and the SIMANFOR platform to simulate the evolution of CO2 stock (CO2 Mg · ha⁻¹) and accumulation rates (CO2 Mg · ha⁻¹ · year⁻¹) for the 2000–2100 period in pure and mixed stands managed under different Shared Socioeconomic Pathways (SSPs) in Spain. We hypothesized that (1) the more optimistic climate scenarios (SSP1 > > SSP5) would have higher CO2 stock and accumulation rates; (2) mixed stands would have higher CO2 stock and accumulation rates than pure stands; and (3) the behavior of both variables would vary based on forest composition (conifer–conifer vs. conifer–broadleaf). We focused on Pinus sylvestris L., and its main mixtures with Pinus nigra, Pinus pinaster, Fagus sylvatica and Quercus pyrenaica. The SSP scenarios had correlating CO2 stock values in which SSP1 > SSP2 > SSP3 > SSP5, ranging from the most optimistic (SSP1) to the most pessimistic (SSP5). Though pure stands had higher CO2 stock at the beginning, differences with regard to mixed stands were drastically reduced at the end of the simulation period. We also found an increase in the aboveground CO2 proportion compared to belowground in conifer–broadleaf mixtures, while the opposite trend occurred in conifer–conifer mixtures. Overall CO2 accumulation rates decreased significantly from the beginning to the end of the simulation period, but our results indicated that this decline would be less drastic in mixed stands than in pure ones. At the end of the simulation period, CO2 accumulation rates were higher in mixed stands than in pure stands for all mixtures, fractions (aboveground and belowground) and SSPs. Knowing the evolution of mixed forests in different climate scenarios is relevant for developing useful silvicultural guidelines in the Mediterranean region and optimizing forestry adaptation strategies. Better understanding can also inform the design of management measures for transitioning from pure stands to more resource efficient, resistant and resilient mixed stands, in efforts to reduce forest vulnerability in the face of climate change. This work highlights the importance and benefits of mixed stands in terms of CO2 accumulation, stand productivity and species diversity.
... In addition to niche partitioning, selection effects have been suggested as a mechanism of overyielding. Selection effects occur because productive species are more likely to be present in more diverse communities than less diverse communities (Aarssen, 1997). Although important, niche partitioning and selection effects remain difficult to quantify Clark et al., 2019;Mueller et al., 2013) and explain only a modest proportion of the large amount of variation in biomass production in diversity-productivity experiments (Cardinale et al., 2007;Hector et al., 2002). ...
Plant productivity often increases with species richness, but the mechanisms explaining this diversity–productivity relationship are not fully understood. We tested if plant–soil feedbacks (PSF) can help to explain how biomass production changes with species richness. Using a greenhouse experiment, we measured all 240 possible PSFs for 16 plant species. At the same time, 49 plant communities with diversities ranging from one to 16 species were grown in replicated pots. A suite of plant community growth models, parameterized with (PSF) or without PSF (Null) effects, was used to predict plant growth observed in the communities. Selection effects and complementarity effects in modeled and observed data were separated. Plants created soils that increased or decreased subsequent plant growth by 25% ± 10%, but because PSFs were negative for C3 and C4 grasses, neutral for forbs, and positive for legumes, the net effect of all PSFs was a 2% ± 17% decrease in plant growth. Experimental plant communities with 16 species produced 37% more biomass than monocultures due to complementarity. Null models incorrectly predicted that 16‐species communities would overyield due to selection effects. Adding PSF effects to Null models decreased selection effects, increased complementarity effects, and improved correlations between observed and predicted community biomass. PSF models predicted 26% of overyielding caused by complementarity observed in experimental communities. Relative to Null models, PSF models improved the predictions of the magnitude and mechanism of the diversity–productivity relationship. Results provide clear support for PSFs as one of several mechanisms that determine diversity–productivity relationships and help close the gap in understanding how biodiversity enhances ecosystem services such as biomass production.
... One potential reason for the strong seasonality in diversity effects on clumpiness could be that plant species show phenological asymmetry which might lead to prolonged periods of low plant-plant interaction. In addition to the phenological asymmetry, there is a higher likelihood of having stronger competitors in more diverse communities [63][64][65]. This is both true for Geranium pratensis L., which is a dominant and late flowering species. ...
Increasing plant diversity commonly enhances standing biomass and other ecosystem
functions (i.e., carbon fluxes, water use efficiency, herbivory). The standing biomass is correlated
with vegetation volume, which describes plant biomass allocation within a complex canopy structure.
As the canopy structure of plant communities is not static throughout time, it is expected that
its changes also control diversity effects on ecosystem functioning. Yet, most studies are based on
one or two measures of ecosystem function per year. Here, we examine the temporal effects of diversity
of grassland communities on canopy structural components in high temporal (bi-weekly
throughout the growing season) and spatial resolutions as a proxy for ecosystem functioning. Using
terrestrial laser scanning, we estimate metrics of vertical structure, such as biomass distribution
(evenness) and highest biomass allocation (center of gravity) along height strata. For horizontal
metrics, we calculated community stand gaps and canopy surface variation. Our findings show that
species-rich communities start filling the vertical space (evenness) earlier in the growing season,
suggesting a more extended period of resource use (i.e., light-harvesting). Moreover, more diverse
communities raised their center of gravity only at the peak of biomass in spring, likely triggered by
higher interspecific competition inducing higher biomass allocation at upper layers of the canopy.
Furthermore, richer communities were clumpier only after mowing, revealing species-specific differences
in regrowth. Lastly, species richness strongly affected canopy variation when the phenology
status and height differences were maximal, suggesting differences in plant functional strategies
(space to grow, resource use, and flowering phenology). Therefore, the effects of diversity on
ecosystem functions depending on those structural components such as biomass production, decomposition,
and herbivory, may also change throughout the season due to various mechanisms,
such as niche differences, increased complementarity, and temporal and spatial variation in biological
activity.
... temperature and soil humidity; Prescott & Grayston, 2013). Plant diversity effects can be expressed, for example, through disproportional effects (either positive or negative) of specific plant species on soil micro-organisms, that is the sampling effect hypothesis (Aarssen, 2016;Huston, 1997;Tilman et al., 1997). Species with complementary traits can also lead to non-additive effects on soil micro-organism activities, for example, through the combination of varying litter qualities (Barantal et al., 2014;Handa et al., 2014) and/or increased root exudate diversity or rate of diffusion (Cesarz et al., 2013;Jones et al., 2004;Prescott & Grayston, 2013). ...
... Below the taxonomic threshold point of the salinity gradient along the medium spatial scale, benthic biomass correlated negatively with species richness, i.e., communities with lowest number of diatom species contained the highest amount of Chl a. Possible reasons for such a negative diversityecosystem functioning relationship include, e.g., highly productive species in species-poor communities (Aarssen, 1997), negative biotic interactions, such as growth inhibition which is a common mechanism in aquatic systems and reduces the performance of keystone species (Leflaive and Ten-Hage, 2007), or low genetic diversity of dominant species in species-rich communities (Crawford and Rudgers, 2012). Although diatoms often dominate in cold and temperate waters (Watermann et al., 1999), other autotrophic organisms, such as cyanobacteria and green algae, may also contribute to the negative relationship between diatom species richness and benthic biomass. ...
The responses of biotic communities and ecosystems to climate change may be abrupt and non-linear. Thus, resolving ecological threshold mechanisms is crucial for understanding the consequences of climate change and for improving environmental management. Here, we present a study on the threshold responses of benthic diatom communities that are an important component of all aquatic environments and strongly contribute to global primary production. We reach beyond the taxonomic perspective by focusing on the diversity and functions of diatom communities and benthic biomass along gradients of salinity and wind disturbance, whose climate-change-induced changes have been predicted to strongly affect biotic communities in the marine and brackish systems in the future. To improve the generality of our results, we examine three self-collected datasets from different spatial scales (6–830 km) and ecosystem types. We collected samples from rock pools or from littoral stones and studied taxonomic thresholds using Threshold Indicator Taxa Analysis (TITAN2). We investigated threshold responses of community diversity, community functions, and benthic biomass using t-tests and regression analysis. Our results indicated that decreasing salinity may result in increasing diversity but decreasing biomass of brackish communities, while the effects of increasing wind disturbance were contradictory among spatial scales. Benthic biomass correlated with the taxonomic and functional diversity, as well as with the body size distribution of communities, highlighting the importance of considering community functions and organismal size when predicting ecosystem functions. The most pronounced effects of decreasing salinity and increasing wind disturbance on community functions were changes in the abundance of low-profile diatom species, which, due to the high resilience of low-profile diatoms, may lead to changes in ecosystem functioning and resilience. To conclude, decreasing salinity and increasing wind disturbance may lead to threshold responses of biotic communities, and these changes may have profound effects on ecosystem functioning along marine coastal areas.
... The floristic composition of padang was the least among the three habitat types. This is because of the physical conditions in padang that were very open with extreme environmental conditions, thus only species that are tolerant to sunlight and able to adapt to nutrient-poor conditions can survive in padang (Aarssen 1997;Liu et al. 2006;Maire et al. 2012). Pioneer species found in padang included the Fimbrystilis sp., Panicum sp., and L. cernuum. ...
Oktavia D, Pratiwi SD, Munawaroh S, Hikmat A, Hilwan I. 2021. Floristic composition and species diversity in three habitat types of heath forest in Belitung Island, Indonesia. Biodiversitas 22: 5555-5563. Exploring plant diversity, structure, and composition of vegetation in forest ecosystems is necessary for understanding the mechanism of species coexistence and forest dynamics, moreover in a unique and vulnerable ecosystem such as tropical heath forest (kerangas). We investigated the composition and structure of vegetation of heath forests in East Belitung, Indonesia in three habitat types, namely primary heath forest (rimba), secondary heath forest (bebak), and grassland (padang). Vegetation analysis was conducted using the combination of transect and plot method to calculate the importance value index (IVI) for all species and biodiversity indicators for each habitat type. We recorded 157, 135, and 31 species in rimba, bebak, and padang, respectively. The top three dominant families of species found were Myrtaceae, Clusiaceae, and Euphorbiaceae. In rimba, Syzygium lepidocarpa had the highest IVI for seedlings, Calophyllum lanigerum had the highest IVI for saplings, and Schima walichii had the highest IVI for trees. In bebak, Guioa pleuropteris had the highest IVI for seedlings, Garcinia hombroniana had the highest IVI for saplings, and Schima walichii had the highest IVI for trees. In padang, Fimbristylis sp. had the highest IVI for seedlings, while Leptospermum flavescens had the highest IVI for saplings and trees. Some pioneer species were found such as Rhodomyrtus tomentosa, Rhodamnia cinerea, Syzygium buxifolium. We also found two carnivorous plants Drosera burmannii and Nepenthes gracilis in padang, indicating that this habitat type is poor in nutrients in the soils. We suggested that the presence of species composition in the three habitat types of heath forest is an essential plant resource to be conserved and sustainably utilized. Establishing reserve areas to protect natural habitat and biodiversity is encouraged to provide proper ecosystem function for the people and nature.
... The dominant species usually account for a high proportion of the biomass. Both theory and experimental evidence (Huston 1997;Aarssen 1997) suggest that the extent to which a plant species affects ecosystem functions is likely to be closely predictable from its contribution to the total plant biomass. Massratio theory proposes that immediate controls are proportional to primary production inputs and are determined to an overwhelming extent by the traits and functional diversity of the dominant species (Grime 1998). ...
Studies of the spatial patterns of dominant plant species may provide significant insights into processes and mechanisms that maintain stand stability. This study was performed in a permanent 1 ha plot in evergreen and deciduous broad-leaved mixed forests on Tianmu Mountain. Based on two surveys (1996 and 2012), the dynamics of the spatial distribution pattern of the dominant population ( (Blume) Oersted) and the intra- and interspecific relationships between and other dominant species populations were analyzed using Ripleyâs () function. We identified the importance value of a species in a community, which is the sum of the relative density, relative frequency, and relative dominance. The drivers of spatial distribution variation and the maintenance mechanisms of the forest were discussed. The results showed that the importance value of within the community decreased over the past 16 years. The population exhibited a significantly aggregated distribution within a spatial scale of 0â25 m in 1996 whereas it changed to a random distribution at scales larger than 5.5 m in 2012. From 1996 to 2012, the spatial distribution patterns between and (Batal.) Iljinsk. and between and (Lamb.) Hook did not change significantly. In 1996, and Miq. were positively associated at the scale of 0â25 m; this relationship was strongly significant at the scale of 6â10 m. However, there was no association between the populations of two species in terms of the spatial distribution at the scale of 0â25 m in 2012. Our findings indicate that the drivers of variation in the spatial distribution of the population were intra- and interspecific mutual relationships as well the seed-spreading mechanism of this species. Cyclobalanopsis myrsinifolia C. myrsinifolia K r C. myrsinifolia C. myrsinifolia C. myrsinifolia Cyclocarya paliurus C. myrsinifolia Cunninghamia lanceolata C. myrsinifolia Daphniphyllum macropodum C. myrsinifolia
... temperature and soil humidity; Prescott & Grayston, 2013). Plant diversity effects can be expressed, for example, through disproportional effects (either positive or negative) of specific plant species on soil micro-organisms, that is the sampling effect hypothesis (Aarssen, 2016;Huston, 1997;Tilman et al., 1997). Species with complementary traits can also lead to non-additive effects on soil micro-organism activities, for example, through the combination of varying litter qualities (Barantal et al., 2014;Handa et al., 2014) and/or increased root exudate diversity or rate of diffusion (Cesarz et al., 2013;Jones et al., 2004;Prescott & Grayston, 2013). ...
Plant community composition influences soil microbial communities through plant trait variations that lead to changes in nutrient and organic carbon inputs into the soil by root exudates and plant litter. Although plant litter and living roots are known to influence microbial functioning independently, their relative effects are rarely measured simultaneously in naturally occurring plant communities.
Here, we sought to evaluate how forest floor litter and absorptive roots affect broad functions of soil microbial communities, and how this may be influenced by tree species mixing. To do so, forest floor litter, absorptive roots and soil were sampled from mono‐specific and three‐species mixed stands in four mature, natural forest ecosystems across Europe. The direct effects of tree species mixing, its indirect effects via litter and root traits, and the effects of soil parameters on microbial biomass, catabolic activity and diversity, and denitrification were analysed.
Results did not show direct tree mixture effects on the soil microbial parameters we measured but did suggest indirect influences via tree mixture effects on traits of above‐ground litter and absorptive roots and soil parameters. Mixed forests composed of any three tree species modified soil microbial functioning by influencing nutrient availability in forest floor litter and root resource acquisition. Tree mixing also modified soil microbial functioning and catabolic diversity by influencing soil fertility and physicochemical properties.
Our findings suggest an indirect but present influence of tree species mixing on the activity of heterotrophic soil microbial communities across four different forest ecosystems ranging from Mediterranean to boreal forests. Our study contributes to a better mechanistic understanding of mixed tree species effects on soil microbial functioning via the modification of forest floor litter properties and traits of absorptive roots represented by the tree community beyond simple species number consideration, and potentially via soil properties.
A free Plain Language Summary can be found within the Supporting Information of this article.
... An earlier study found that the development of a pioneer species population can promote an improvement in habitat conditions (Aarssen, 1997), and a change in the dominant species during the pioneer stage will result in an adjustment in the inter-specific relationship of the community (Peng and Ying, 2016). However, the population dynamics of pioneer species is inherently unstable, undergoing population expansion during the early stage and thereafter a decline in population during the latter stage (Kenkel et al. 1997;Xu et al. 2015). ...
As a dominant and active component across ecological restoration processes, the population dynamics of pioneer tree species significantly affect species composition and community assemblage. To assess the effect of pioneer populations on species diversity, this study investigated species diversity and population characteristics in five secondary forests dominated by Pinus massoniana in southeastern China. For 40 years, all anthropogenic activities (e.g., logging, farming, etc.) have been banned on the hillsides of these five secondary forests to promote afforestation, for which these forests have thereafter been left to grow naturally. We found that: (1) the basal area (BA) of P. massoniana drove changes in species diversity across forest plots, explaining 31.6% of total variation. The species richness of the herb layer was negatively correlated to BA, while the diversity and evenness of the tree and shrub layers were both positively correlated to the BA. (2) As the size of individual P. massoniana specimens increased, the trend in species richness of the shrub layer and the diversity indexes of both the tree and shrub layer was first to increase and then to decrease once again, while the species richness of the tree layer stabilized after reaching a certain threshold. (3) Species diversity of the forest plots did not improve over time along with an increase in the density of the pioneer species. When the P. massoniana population density was low, the diversity indexes of both the tree and shrub layer increased with an increase in population density. Conversely, when the P. massoniana population density reached 2800 plants/ha, species diversity began to decline. However, when the P. massoniana population density increased to 3733 plants/ha, species diversity of the plant community exhibited an upward trend. Our results indicated that forest species diversity was extremely sensitive to P. massoniana population dynamics during the pioneer stage of ecological succession. Moreover, the pioneer population was the driving factor for both development and change in species diversity, and it did so through habitat adjustment of its ecological relationships.
... We show that biodiversity had a significant impact on most EEAs, but the strength of the effect depended on the substrate context. This might explain why the relationship between biodiversity and community ecosystem functioning cannot always be predicted to be positive as previously observed (Aarssen 1997;Tilman 1997;Huston 2000;Carroll, Cardinale and Nisbet 2011). Natural, larger scale experiments struggle with introducing different levels of complexity in their experimental design (Cairns et al. 2018). ...
Quantifying the relative contributions of microbial species to ecosystem functioning is challenging, because of the distinct mechanisms associated with microbial phylogenetic and metabolic diversity. We constructed bacterial communities with different diversity traits and employed exoenzyme activities (EEAs) and carbon acquisition potential (CAP) from substrates as proxies of bacterial functioning to test the independent effects of these two aspects of biodiversity. We expected that metabolic diversity, but not phylogenetic diversity would be associated with greater ecological function. Phylogenetically relatedness should intensify species interactions and coexistence, therefore amplifying the influence of metabolic diversity. We examined the effects of each diversity treatment using linear models, while controlling for the other, and found that phylogenetic diversity strongly influenced community functioning, positively and negatively. Metabolic diversity, however, exhibited negative or non-significant relationships with community functioning. When controlling for different substrates, EEAs increased along with phylogenetic diversity but decreased with metabolic diversity. The strength of diversity effects was related to substrate chemistry and the molecular mechanisms associated with each substrate's degradation. EEAs of phylogenetically similar groups were strongly affected by within-genus interactions. These results highlight the unique flexibility of microbial metabolic functions that must be considered in further ecological theory development.
... If functional identity, quantified as community mean trait expression (Cingolani et al., 2007;Fonseca et al., 2000), is a strong predictor of functioning, we may conclude that an identity effect is operating. In this case, increasing diversity increases the chance of including species with specific trait values that have strong effects on functioning (Aarssen, 1997;Grime, 1998;Huston, 1997). If in turn, functional diversity of grassland communities, a facet of biodiversity determined by the dispersion of species traits in multidimensional trait space (Lalibert e and Legendre, 2010), emerges as a strong predictor of plant development, we might infer that resource partitioning is an important driver of BEF relationships. ...
Biodiversity often enhances ecosystem functioning likely due to multiple, often temporarily
separated drivers. Yet, most studies are based on one or two snapshot measurements
per year. We estimated productivity using bi-weekly estimates of high-resolution
canopy height in 2 years with terrestrial laser scanning (TLS) in a grassland diversity
experiment. We measured how different facets of plant diversity (functional dispersion
[FDis], functional identity [PCA species scores], and species richness [SR]) predict aboveground
biomass over time. We found strong intra- and inter-annual variability in the
relative importance of different mechanisms underlying the diversity effects on mean
canopy height, i.e., resource partitioning (via FDis) and identity effects (via species
scores), respectively. TLS is a promising tool to quantify community development
non-destructively and to unravel the temporal dynamics of biodiversity-ecosystem
functioning mechanisms. Our results show that harvesting at estimated peak
biomass—as done in most grassland experiments—may miss important variation in
underlying mechanisms driving cumulative biomass production.
... The studies of Naeem et al. (1994) and Tilman et al. (1996Tilman et al. ( , 1997b have been criticized because the relationships between diversity and productivity can be explained by species identity rather than diversity per se (Aarssen 1997, Huston 1997). Huston and Aarssen argued that in the species-rich plots, in which a larger number of species were randomly selected from a pool of species, it was more likely that species with high growth rates were selected and that species rich plots had higher productivity because of species identity rather than diversity. ...
... Some interpretations suggest that abundant species are most important in maintaining ecosystem function (Aarssen 1997, Kleijn et al. 2015. Evidence is growing, however, that rare species maintain key functional diversity and may have disproportionate effects on foodweb structure (Zavaleta and Hulvey 2004, Bracken and Low 2012, Mouillot et al. 2013. ...
... Two mechanisms for BEF relationships have been proposed: (1) the selection effect, in which multispecies communities have a higher probability of containing a species/genotype that supports greater functions; and (2) the complementarity effect, in which species/genotypes facilitate each other or have complementary resource use (Aarssen, 1997;Loreau & Hector, 2001). In this study, we calculated net effects and transgressive overyielding of genotypic diversity on total belowground plant biomass of Phragmites australis, abundance and richness of total nematodes and of each nematode feeding group, and nematode metabolic footprints. ...
At local spatial scales, loss of genetic diversity within species can lead to species loss. Few studies, however, have examined plant genotypic diversity effects across trophic levels.
We investigated genotypic diversity effects of Phragmites australis on belowground biomass and soil nematode communities.
Our results revealed that belowground plant biomass and nematode abundance responses to plant genotypic diversity were uncoupled. Decreasing plant genotypic diversity decreased the abundance of lower, but not higher trophic level nematodes. Low plant genotypic diversity also decreased the structural footprint and functional indices of nematodes, indicating lowered metabolic functioning of higher trophic level nematodes and decreased soil food web stability.
Our study suggests that plant genotypic diversity effects differ across trophic levels, taxonomic groups and ecosystem functions and that decreasing plant genotypic diversity could destabilise belowground food webs. This highlights the importance of conserving intraspecific plant diversity.
Natural ecosystems store large amounts of carbon globally, as organisms absorb carbon from the atmosphere to build large, long-lasting, or slow-decaying structures such as tree bark or root systems. An ecosystem’s carbon sequestration potential is tightly linked to its biological diversity. Yet when considering future projections, many carbon sequestration models fail to account for the role biodiversity plays in carbon storage. Here, we assess the consequences of plant biodiversity loss for carbon storage under multiple climate and land-use change scenarios. We link a macroecological model projecting changes in vascular plant richness under different scenarios with empirical data on relationships between biodiversity and biomass. We find that biodiversity declines from climate and land use change could lead to a global loss of between 7.44-103.14 PgC (global sustainability scenario) and 10.87-145.95 PgC (fossil-fueled development scenario). This indicates a self-reinforcing feedback loop, where higher levels of climate change lead to greater biodiversity loss, which in turn leads to greater carbon emissions and ultimately more climate change. Conversely, biodiversity conservation and restoration can help achieve climate change mitigation goals.
The Upper Silesia region of Poland is one of the most extensively altered regions of Europe due to human activity, especially coal mining. (2): We used cluster analysis to examine the floristic composition of three classified forest communities: forests developed on post-coal mine mineral heaps (HF), mixed deciduous forests (DECI), and managed secondary coniferous forests (CON). Vegetation data were collected from 44 randomly selected plots, and plant traits connected with persistence, dispersal, and regeneration were taken from commonly used plant trait databases. (3): Higher species richness, species diversity, and evenness (36, 2.7, and 0.76, respectively) were calculated for HF plots compared with those plots from DECI (22, 1.9, and 0.62) and CON (18, 2.0, and 0.71) plots. Higher functional richness (0.173, 0.76) and functional divergence were determined for HF compared with those calculated for DECI (FRic 0.090, FDiv 0.71) and CON (FRic 0.026, FDiv 0.69). In contrast, the substrate from HF forests had significantly lower soil respiration (0.76 mg-CO 2 h/m 2) compared with substrates from both CON and DECI forests (0.90 and 0.96 mg-CO 2 h/m 2 , respectively); (4): A set of complex abiotic stresses which plants suffer from on coal mine spoil heaps shaped different patterns of taxonomic and functional diversity. These findings demonstrate the importance of investigating successional aspects and carbon dynamics of de novo forests which have developed on post-coal mine spoil heaps in urban industrial areas.
This paper investigates the dynamical behavior of the modified May–Holling–Tanner model in the presence of dynamic alternative resources. We study the role of dynamic alternative resources on the survival of the species when there is prey rarity. Detailed mathematical analysis and numerical evaluations, including the situation of ecosystem collapsing, have been presented to discuss the coexistence of species’, stability, occurrence of different bifurcations (saddle-node, transcritical, and Hopf) in three cases in the presence of prey and alternative resources, in the absence of prey and in the absence of alternative resources. It has been obtained that the multiple coexisting states and their stability are outcomes of variations in predation rate for alternative resources. Also, the occurrence of Hopf bifurcation, saddle-node bifurcation, and transcritical bifurcation are due to variations in the parameters of dynamic alternative resources. The impact of dynamic alternative resources on species’ density reveals the fact that if the predation rate for alternative resources increases, then the prey biomass increases (under some restrictions), and variations in the predator’s biomass widely depend upon the quality of food items. This study also points out that the survival of predators is possible in the absence of prey. In the theme of ecological balance, this study suggests some theoretical points of view for the eco-managers.
The loss of species following disturbances may reduce the resilience of ecosystems to stress. It is thus understood that diversity of plant species may affect the functional processes in a disturbed ecosystem. This paper reports on the biomass accumulation patterns in litter, roots, and microbial biomass across changing community characteristics along a successional gradient in a regrowing broadleaved forest following felling and in a pine forest on abandoned agricultural lands in a subtropical environment of north-eastern India. The species diversity index had a linear relationship with litter, fine roots and microbial biomass accumulation in the broadleaved forest regrowths, while density and basal area of pine trees were negatively correlated to these functional processes. Over all, there were significant positive correlations among litter, fine roots and microbial biomass. These results suggest that woody vegetation characteristics could be an index to explain the biomass dynamics of the three soil biological processes that increased during community development following disturbances. Species evenness index had no relationships with the biological processes. Nevertheless, the usage of community characteristics as an index of biological processes could be ecosystem specific in general and type of successional vegetation in particular.
One of the most invoked mechanisms mediating the positive effect of pollinator diversity on plant reproduction is pollinator's niche complementarity (i.e. partitioning of resource use by different pollinator species). However, the influence of spatial and temporal pollinator's niche complementarity on crop pollination function is rarely tested. We investigated the influence of spatial and temporal niche complementary in explaining sunflower crop production by comparing pollination activity at the edge and centre of crop fields and over the day. We found weaker evidence for spatial niche complementarity than for temporal niche complementarity in pollinator visitation rates. Only the visitation rate of hoverflies slightly differed between the centre and the edge of the fields. Nevertheless, we observed no differences in seed weight between the edge and the centre of the fields, but interestingly, plants allowed to be pollinated only by small-sized pollinators experienced a decline in seed production with distance from the edge. Pollinators did show complementary peak activity periods throughout the day, with Bombus terrestris and honeybees preferring to forage early in the day and at cooler temperatures than B. lapidarius and solitary bees. Unexpectedly, only morning- and only afternoon-pollinated plants produced similar seed weights, but these were higher than in all-day exposed plants. These findings indicate that sunflower fields shelter a small number of complementary pollinator species groups, which become rapidly redundant as diversity increases. Overall, we show that temporal and spatial niche complementarity effects on yield can unfold in unexpected ways, which are hard to predict without testing for the specific mechanisms.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
What can ecological science contribute to the sustainable management and conservation of the natural systems that underpin human well-being? Bridging the natural, physical and social sciences, this book shows how ecosystem ecology can inform the ecosystem services approach to environmental management. The authors recognise that ecosystems are rich in linkages between biophysical and social elements that generate powerful intrinsic dynamics. Unlike traditional reductionist approaches, the holistic perspective adopted here is able to explain the increasing range of scientific studies that have highlighted unexpected consequences of human activity, such as the lack of recovery of cod populations on the Grand Banks despite nearly two decades of fishery closures, or the degradation of Australia's fertile land through salt intrusion. Written primarily for researchers and graduate students in ecology and environmental management, it provides an accessible discussion of some of the most important aspects of ecosystem ecology and the potential relationships between them.
What can ecological science contribute to the sustainable management and conservation of the natural systems that underpin human well-being? Bridging the natural, physical and social sciences, this book shows how ecosystem ecology can inform the ecosystem services approach to environmental management. The authors recognise that ecosystems are rich in linkages between biophysical and social elements that generate powerful intrinsic dynamics. Unlike traditional reductionist approaches, the holistic perspective adopted here is able to explain the increasing range of scientific studies that have highlighted unexpected consequences of human activity, such as the lack of recovery of cod populations on the Grand Banks despite nearly two decades of fishery closures, or the degradation of Australia's fertile land through salt intrusion. Written primarily for researchers and graduate students in ecology and environmental management, it provides an accessible discussion of some of the most important aspects of ecosystem ecology and the potential relationships between them.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
Forests hold a significant proportion of global biodiversity and terrestrial carbon stocks and are at the forefront of human-induced global change. The dynamics and distribution of forest vegetation determines the habitat for other organisms, and regulates the delivery of ecosystem services, including carbon storage. Presenting recent research across temperate and tropical ecosystems, this volume synthesises the numerous ways that forests are responding to global change and includes perspectives on: • the role of forests in the global carbon and energy budgets • historical patterns of forest change and diversification • contemporary mechanisms of community assembly and implications of underlying drivers of global change • the ways in which forests supply ecosystem services that support human lives. The chapters represent case studies drawn from the authors' expertise, highlighting exciting new research and providing information that will be valuable to academics, students, researchers and practitioners with an interest in this field.
Understanding the role of biodiversity in maintaining ecosystem functioning and stability under increasing frequency and magnitude of climatic extremes has fascinated ecologists for decades. Although growing evidence suggests that biodiversity affects ecosystem productivity and buffers ecosystem against climatic extremes, it remains unclear whether the stability of an ecosystem is caused by its resistance against disturbances or resilience towards perturbations or both. In attempting to explore how species richness affects resistance and resilience of above-ground net primary productivity (ANPP) against climatic extremes, we analyzed the grassland ANPP of the long-running (1997–2020) Bayreuth Biodiversity experiment in Germany. We used the Standardized Precipitation Evapotranspiration Index to identify climatic conditions based on 5- and 7-class classifications of climatic conditions. Mixed-effects models and post-hoc test show that ANPP varied significantly among different intensities (e.g. moderate or extreme) and directions (e.g. dry or wet) of climatic conditions, with the highest ANPP in extreme wet and the lowest in extreme dry conditions. Resistance and resilience of ANPP to climatic extremes in different intensities were examined by linear-mixed effects models and we found that species richness increased ecosystem resistance against all dry and wet climatic extremes, but decreased ecosystem resilience towards all dry climatic extremes. Species richness had no effects on ecosystem resilience towards wet climatic extremes. When the five level of species richness treatment (i.e., 1, 2, 4, 8, and 16 species) were considered, the relationships between species richness and resistance and resilience of ANPP under extreme wet and dry conditions remained similar. Our study emphasizes that plant communities with greater species richness need to be maintained to stabilize ecosystem productivity and increase resistance against different climatic extremes.
This chapter reviews progress, evidence, and challenges for understanding the consequences of biodiversity change for ecosystem functioning in observational data. It reviews both the benefits and challenges of observational data, as different analysis designs and considerations are needed for causal inference when controlled manipulative experiments are not possible. Observational studies can help us understand the consequences of biodiversity change for ecosystem functioning at larger scales. Temperate ecosystems were the most studied in the context of biodiversity and ecosystem functioning (BEF) relationships, namely temperate forests and woodlands and temperate grasslands. Urban and peri‐urban ecosystems have also received relatively little attention in the realm of BEF research. Statistical designs and methods appropriate for observational studies can be applied to global change experiments to understand how changes in function are driven by changes in biodiversity. The chapter concludes by highlighting research gaps and methodological opportunities to advance our understanding of biodiversity‐functioning relationships in natural systems, across multiple scales.
Given the unprecedented and growing threats to inland waters — eutrophication, cyanobacterial blooms, over-exploitation, and climate change — from multiple human activities, biodiversity is decreasing at faster rates in freshwater ecosystems than in marine or terrestrial. Since the early 1990s, hundreds of studies attempted to explain how ecosystems respond to biodiversity loss and how changes in biodiversity scale up to affect ecosystem functioning, as well as the provision of goods and services to humans. Recent studies have demonstrated that such biodiversity responses are commonly trait-mediated and the effects of communities on ecosystem functioning also depend on species traits. However, it remains unclear to what extent such biodiversity responses translate into changes in the rates of many ecosystem processes in naturally assembled communities. In this doctoral dissertation, I aimed at evaluating the effects of nutrient availability and cyanobacteria dominance on structure and composition of plankton communities (phytoplankton and zooplankton), and on two important ecosystem functions in aquatic systems: phytoplankton resource use efficiency (RUE) of limiting nutrients — phosphorus and nitrogen — and zooplankton top-down control of algae. For this, I structured this doctoral dissertation in three chapters to explore the mechanisms that underlie biodiversity-ecosystem functioning (B-EF) relationships, using a combination of experimental and fieldwork approaches, together with multiple aspects of biodiversity (i.e., taxonomic and functional diversity). In the first chapter, I and my coauthors analyzed the relationship between different measures of phytoplankton diversity, temporal turnover and RUE using 8-years monitoring data set from a cyanobacteria-dominated subtropical lake, which is now experiencing a shift in the trophic state from oligo-mesotrophic to eutrophic. Additionally, we aimed at evaluating the effect of resource availability on phytoplankton community structure and RUE. In the second chapter, using 1-year monitoring data set from the same lake, we evaluated the relative importance of size-based and taxon-based approaches in explaining the strength of zooplankton top-down control on algae, and also aimed at disentangling the mechanism by which zooplankton body size drives such ecosystem function. Finally, in the third chapter, we used an experimental metacommunity approach that simulated typical gradients of productivity and plant structural complexity to test how zooplankton body size diversity and composition responded to such gradients and whether and how such trait responses impacted top-down control of algae. Through these three chapters, we demonstrated that under environmental changes (i.e., nutrient increase and prolonged cyanobacteria dominance) approaches based on body size and taxonomic richness complement each other in explaining variation in zooplankton top-down control. Our results clearly indicate that zooplankton body size explains a substantial and independent part of the variance in top-down control, which corroborates several studies demonstrating the role of zooplankton body size to control phytoplankton biomass. But contrary to our expectations, species richness also plays a role, indicating that species richness may adequately represent some unmeasured traits that also influence ecosystem functioning. Moreover, we demonstrated that different aspect of biodiversity might have divergent responses and divergent effects on ecosystem functioning depending on environmental perturbation, which highlight the importance of considering multiple aspects of biodiversity — taxonomic and functional approaches — in B-EF research. Overall, our results illustrated the potential for trait-based approaches to reveal biodiversity responses to environmental change and their generalizable effects on ecosystems. Furthermore, given the lack of large grazers in tropical and subtropical regions, and the evidence that Cyanobacteria dominance will increase in freshwater ecosystems under the predicted future climate, the results herein highlight the concern about the energy flow in aquatic systems dominated by Cyanobacteria.
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