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Lenore Fahrig - One of the best experts on this subject based on the ideXlab platform.
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Is Habitat Fragmentation bad for biodiversity
Biological Conservation, 2019Co-Authors: Lenore Fahrig, Víctor Arroyo-rodríguez, Joseph R. Bennett, Véronique Boucher-lalonde, Eliana Cazetta, David J. Currie, Felix Eigenbrod, Adam T. Ford, Susan Harrison, Jochen A.g. JaegerAbstract:In a review of landscape-scale empirical studies, Fahrig (2017a) found that ecological responses to Habitat Fragmentation per se (Fragmentation independent of Habitat amount) were usually non-significant (>70% of responses) and that 76% of significant relationships were positive, with species abundance, occurrence, richness, and other response variables increasing with Habitat Fragmentation per se. Fahrig concluded that to date there is no empirical evidence supporting the widespread assumption that a group of small Habitat patches generally has lower ecological value than large patches of the same total area. Fletcher et al. (2018) dispute this conclusion, arguing that the literature to date indicates generally negative ecological effects of Habitat Fragmentation per se. They base their argument largely on extrapolation from patch-scale patterns and mechanisms (effects of patch size and isolation, and edge effects) to landscape-scale effects of Habitat Fragmentation. We argue that such extrapolation is unreliable because: (1) it ignores other mechanisms, especially those acting at landscape scales (e.g., increased Habitat diversity, spreading of risk, landscape complementation) that can counteract effects of the documented patch-scale mechanisms; and (2) extrapolation of a small-scale mechanism to a large-scale pattern is not evidence of that pattern but, rather a prediction that must be tested at the larger scale. Such tests were the subject of Fahrig's review. We find no support for Fletcher et al.'s claim that biases in Fahrig's review would alter its conclusions. We encourage further landscape-scale empirical studies of effects of Habitat Fragmentation per se, and research aimed at uncovering the mechanisms that underlie positive Fragmentation effects.
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Forty years of bias in Habitat Fragmentation research
Oxford Scholarship Online, 2017Co-Authors: Lenore FahrigAbstract:This chapter evaluates biases that contribute to the common misrepresentation of Fragmentation as a major threat to biodiversity. The idea that Habitat Fragmentation seriously threatens biodiversity is so widespread that it might be considered a “conservation biology principle.” However, effects attributed to Habitat Fragmentation are usually confounded with effects of Habitat loss. A recent review of the effects of Habitat Fragmentation per se (effects independent of Habitat loss) indicated that 76% of significant effects of Fragmentation were positive, and in no situation were most effects negative. Comparing the abstracts of papers with the actual results reported in the body of each paper revealed that fewer than half of the authors who found only positive Fragmentation effects actually discuss these positive effects in their abstracts. Thus, authors themselves reinforce the misrepresentation of the Fragmentation literature, potentially because authors fear that their results could be incorrectly used to justify Habitat destruction.
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Ecological Responses to Habitat Fragmentation Per Se
Annual Review of Ecology Evolution and Systematics, 2017Co-Authors: Lenore FahrigAbstract:For this article, I reviewed empirical studies finding significant ecological responses to Habitat Fragmentation per se—in other words, significant responses to Fragmentation independent of the effects of Habitat amount (hereafter referred to as Habitat Fragmentation). I asked these two questions: Are most significant responses to Habitat Fragmentation negative or positive? And do particular attributes of species or landscapes lead to a predominance of negative or positive significant responses? I found 118 studies reporting 381 significant responses to Habitat Fragmentation independent of Habitat amount. Of these responses, 76% were positive. Most significant Fragmentation effects were positive, irrespective of how the authors controlled for Habitat amount, the measure of Fragmentation, the taxonomic group, the type of response variable, or the degree of specialization or conservation status of the species or species group. No support was found for predictions that most significant responses to fragmenta...
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Effects of Habitat Fragmentation on Biodiversity
Annual Review of Ecology Evolution and Systematics, 2003Co-Authors: Lenore FahrigAbstract:■ Abstract The literature on effects of Habitat Fragmentation on biodiversity is huge. It is also very diverse, with different authors measuring Fragmentation in different ways and, as a consequence, drawing different conclusions regarding both the magnitude and direction of its effects. Habitat Fragmentation is usually defined as a landscape-scale process involving both Habitat loss and the breaking apart of Habitat. Results of empirical studies of Habitat Fragmentation are often difficult to interpret because (a) many researchers measure Fragmentation at the patch scale, not the landscape scale and (b) most researchers measure Fragmentation in ways that do not distinguish between Habitat loss and Habitat Fragmentation per se, i.e., the breaking apart of Habitat after controlling for Habitat loss. Empirical studies to date suggest that Habitat loss has large, consistently negative effects on biodiversity. Habitat Fragmentation per se has much weaker effects on biodiversity that are at least as likely to be positive as negative. Therefore, to correctly interpret the influence of Habitat Fragmentation on biodiversity, the effects of these two components of Fragmentation must be measured independently. More studies of the independent effects of Habitat loss and Fragmentation per se are needed to determine the factors that lead to positive versus negative effects of Fragmentation per se. I suggest that the term “Fragmentation” should be reserved for the breaking apart of Habitat, independent of Habitat loss.
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EFFECT OF Habitat Fragmentation ON THE EXTINCTION THRESHOLD: A SYNTHESIS*
Ecological Applications, 2002Co-Authors: Lenore FahrigAbstract:I reviewed and reconciled predictions of four models on the effect of Habitat Fragmentation on the population extinction threshold, and I compared these predictions to results from empirical studies. All four models predict that Habitat Fragmentation can, under some conditions, increase the extinction threshold such that, in more fragmented landscapes, more Habitat is required for population persistence. However, empirical studies have shown both positive and negative effects of Habitat Fragmentation on population abundance and distribution with about equal frequency, suggesting that the models lack some important process(es). The two colonization–extinction (CE) models predict that Fragmentation can increase the extinction threshold by up to 60–80%; i.e., the amount of Habitat required for persistence can shift from 80% of the landscape, with a shift from completely clumped to completely fragmented Habitat. The other two models (birth–immigration–death–emigration, or BIDE models)...
Ramiro Aguilar - One of the best experts on this subject based on the ideXlab platform.
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responses of insect herbivores and herbivory to Habitat Fragmentation a hierarchical meta analysis
Ecology Letters, 2017Co-Authors: María Rosa Rossetti, Teja Tscharntke, Ramiro Aguilar, Péter BatáryAbstract:Loss and Fragmentation of natural Habitats can lead to alterations of plant-animal interactions and ecosystems functioning. Insect herbivory, an important antagonistic interaction is expected to be influenced by Habitat Fragmentation through direct negative effects on herbivore community richness and indirect positive effects due to losses of natural enemies. Plant community changes with Habitat Fragmentation added to the indirect effects but with little predictable impact. Here, we evaluated Habitat Fragmentation effects on both herbivory and herbivore diversity, using novel hierarchical meta-analyses. Across 89 studies, we found a negative effect of Habitat Fragmentation on abundance and species richness of herbivores, but only a non-significant trend on herbivory. Reduced area and increased isolation of remaining fragments yielded the strongest effect on abundance and species richness, while specialist herbivores were the most vulnerable to Habitat Fragmentation. These Fragmentation effects were more pronounced in studies with large spatial extent. The strong reduction in herbivore diversity, but not herbivory, indicates how important common generalist species can be in maintaining herbivory as a major ecosystem process.
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Responses of insect herbivores and herbivory to Habitat Fragmentation: a hierarchical meta‐analysis
Ecology letters, 2017Co-Authors: María Rosa Rossetti, Teja Tscharntke, Ramiro Aguilar, Péter BatáryAbstract:Loss and Fragmentation of natural Habitats can lead to alterations of plant-animal interactions and ecosystems functioning. Insect herbivory, an important antagonistic interaction is expected to be influenced by Habitat Fragmentation through direct negative effects on herbivore community richness and indirect positive effects due to losses of natural enemies. Plant community changes with Habitat Fragmentation added to the indirect effects but with little predictable impact. Here, we evaluated Habitat Fragmentation effects on both herbivory and herbivore diversity, using novel hierarchical meta-analyses. Across 89 studies, we found a negative effect of Habitat Fragmentation on abundance and species richness of herbivores, but only a non-significant trend on herbivory. Reduced area and increased isolation of remaining fragments yielded the strongest effect on abundance and species richness, while specialist herbivores were the most vulnerable to Habitat Fragmentation. These Fragmentation effects were more pronounced in studies with large spatial extent. The strong reduction in herbivore diversity, but not herbivory, indicates how important common generalist species can be in maintaining herbivory as a major ecosystem process.
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Habitat Fragmentation and genetic variability of tetrapod populations
Animal Conservation, 2014Co-Authors: Francisco A. Rivera-ortíz, Ramiro Aguilar, María Del Coro Arizmendi, Mauricio Quesada, Ken OyamaAbstract:In the last two centuries, the development of human civilization has transformed large natural areas into anthropogenic landscapes, making Habitat Fragmentation a pervasive feature of modern landscapes. In animal populations, Habitat Fragmentation may alter their genetic diversity and structure due to limited gene flow and dispersion and reduced effective population sizes, potentially leading to genetic drift in small Habitat patches. We tested the hypothesis that Habitat Fragmentation affects genetic diversity of tetrapod populations through a meta-analysis. We also examined certain life history traits of species and particular external landscape factors that may determine the magnitude of genetic erosion observed in fragmented Habitats. Our results showed that Habitat Fragmentation reduces overall genetic diversity of tetrapod populations. Stronger negative Fragmentation effects were detected for amphibians, birds and mammals. Within each taxonomic group, species with large body size were more strongly affected by Fragmentation. Particularly within mammals, we found that less vagile species with short generation times represent the most susceptible tetrapod group to lose genetic diversity in fragmented Habitats. As external drivers, we found a nonsignificant trend of lower Fragmentation effects in study systems of less than 50 years and stronger effects in older (>100 years) fragmented systems. As expected, the extent of Habitat loss was also important in determining the magnitude of genetic erosion in tetrapods. Extreme Habitat loss showed stronger negative effects on genetic diversity irrespective of taxonomic groups. The information gathered in this review also highlights research bias and gaps in the literature.
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why do pollination generalist and specialist plant species show similar reproductive susceptibility to Habitat Fragmentation
Journal of Ecology, 2004Co-Authors: Lorena Ashworth, Ramiro Aguilar, Leonardo Galetto, Marcelo A AizenAbstract:1Although reproductive success of pollination specialist plants has been predicted to be more sensitive to Habitat Fragmentation than that of generalist plants, recent results indicate that effects do not differ between plants with different degrees of specialization. 2We provide an explanation for such unexpected results by linking evidence that specialization of plant–pollinator interactions is asymmetric to observations that generalist pollinators are less affected by Habitat Fragmentation. 3Plant specialization cannot therefore be considered in isolation from the degree of specialization of the mutualist partners. Evaluation of both sides of the mutualistic interaction will yield insights into the mechanisms behind species’ responses to Habitat Fragmentation.
Jayme A. Prevedello - One of the best experts on this subject based on the ideXlab platform.
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Does Habitat Fragmentation affect landscape-level temperatures? A global analysis
Landscape Ecology, 2020Co-Authors: Clarice B. Mendes, Jayme A. PrevedelloAbstract:Context Habitat Fragmentation per se (Habitat subdivision independent of Habitat loss) is a major driver of biodiversity change, potentially due to its impacts on climate. Habitat Fragmentation may make landscapes hotter by increasing the amount of Habitat edges, but can reduce landscape-level temperatures due to the “vegetation breeze” phenomenon. The plausibility of these two alternative hypotheses is unclear, as no study analyzed the effects of Habitat Fragmentation per se on temperature. Objectives We quantify, for the first time, the impacts of Habitat Fragmentation on landscape-level temperature across the globe. Methods We analyzed satellite data on forest cover and three climatic variables: mean daily temperature, albedo and evapotranspiration. The analyses were performed separately for tropical, temperate, and boreal regions. We compared the climatic variables between pairs of landscapes with similar amount of forest, but different levels of forest Fragmentation (number of patches). Results Habitat Fragmentation reduced landscape-level temperature in all climatic regions. The magnitude of this cooling was stronger in the tropics and weaker in the boreal region due to different evapotranspiration rates. This landscape-scale cooling contradicts local-scale studies, which have indicated that edge effects rise local temperatures. However, Habitat Fragmentation may intensify vegetation breeze, resulting in final cooling at the landscape scale. Conclusions Habitat Fragmentation leads to colder landscapes. We propose a new conceptual model to unify local (edge-induced) and landscape-level effects of Habitat Fragmentation on temperature, advancing the understanding of the consequences of Habitat Fragmentation on climate globally.
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Does Habitat Fragmentation affect landscape-level temperatures? A global analysis
Landscape Ecology, 2020Co-Authors: Clarice B. Mendes, Jayme A. PrevedelloAbstract:Habitat Fragmentation per se (Habitat subdivision independent of Habitat loss) is a major driver of biodiversity change, potentially due to its impacts on climate. Habitat Fragmentation may make landscapes hotter by increasing the amount of Habitat edges, but can reduce landscape-level temperatures due to the “vegetation breeze” phenomenon. The plausibility of these two alternative hypotheses is unclear, as no study analyzed the effects of Habitat Fragmentation per se on temperature. We quantify, for the first time, the impacts of Habitat Fragmentation on landscape-level temperature across the globe. We analyzed satellite data on forest cover and three climatic variables: mean daily temperature, albedo and evapotranspiration. The analyses were performed separately for tropical, temperate, and boreal regions. We compared the climatic variables between pairs of landscapes with similar amount of forest, but different levels of forest Fragmentation (number of patches). Habitat Fragmentation reduced landscape-level temperature in all climatic regions. The magnitude of this cooling was stronger in the tropics and weaker in the boreal region due to different evapotranspiration rates. This landscape-scale cooling contradicts local-scale studies, which have indicated that edge effects rise local temperatures. However, Habitat Fragmentation may intensify vegetation breeze, resulting in final cooling at the landscape scale. Habitat Fragmentation leads to colder landscapes. We propose a new conceptual model to unify local (edge-induced) and landscape-level effects of Habitat Fragmentation on temperature, advancing the understanding of the consequences of Habitat Fragmentation on climate globally.
Raphael K. Didham - One of the best experts on this subject based on the ideXlab platform.
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Is Habitat Fragmentation good for biodiversity
Biological Conservation, 2018Co-Authors: Robert J. Fletcher, Robert M. Ewers, Raphael K. Didham, Cristina Banks-leite, Jos Barlow, James Rosindell, Robert D. Holt, Andrew Gonzalez, Renata Pardini, Ellen I. DamschenAbstract:Abstract Habitat loss is a primary threat to biodiversity across the planet, yet contentious debate has ensued on the importance of Habitat Fragmentation ‘per se’ (i.e., altered spatial configuration of Habitat for a given amount of Habitat loss). Based on a review of landscape-scale investigations, Fahrig (2017; Ecological responses to Habitat Fragmentation per se. Annual Review of Ecology, Evolution, and Systematics 48:1-23) reports that biodiversity responses to Habitat Fragmentation ‘per se’ are more often positive rather than negative and concludes that the widespread belief in negative Fragmentation effects is a ‘zombie idea’. We show that Fahrig's conclusions are drawn from a narrow and potentially biased subset of available evidence, which ignore much of the observational, experimental and theoretical evidence for negative effects of altered Habitat configuration. We therefore argue that Fahrig's conclusions should be interpreted cautiously as they could be misconstrued by policy makers and managers, and we provide six arguments why they should not be applied in conservation decision-making. Reconciling the scientific disagreement, and informing conservation more effectively, will require research that goes beyond statistical and correlative approaches. This includes a more prudent use of data and conceptual models that appropriately partition direct vs indirect influences of Habitat loss and altered spatial configuration, and more clearly discriminate the mechanisms underpinning any changes. Incorporating these issues will deliver greater mechanistic understanding and more predictive power to address the conservation issues arising from Habitat loss and Fragmentation.
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Habitat Fragmentation and biodiversity conservation: key findings and future challenges
Landscape Ecology, 2015Co-Authors: Maxwell C. Wilson, Raphael K. Didham, Robert D. Holt, Xiao-yong Chen, Richard T. Corlett, Ping Ding, Marcel Holyoak, Alice C. Hughes, Lin JiangAbstract:Habitat loss and Fragmentation has long been considered the primary cause for biodiversity loss and ecosystem degradation worldwide, and is a key research topic in landscape ecology (Wu 2013). Habitat Fragmentation often refers to the reduction of continuous tracts of Habitat to smaller, spatially distinct remnant patches, and Habitat loss typically occurs concurrently with Habitat Fragmentation (Collinge 2009). Although some Habitats are naturally patchy in terms of abiotic and biotic conditions (Wu and Loucks 1995), human actions have profoundly fragmented landscapes across the word (Haddad et al. 2015), altering the quality and connectivity of Habitats. Therefore, understanding the causes and consequences of Habitat Fragmentation is critical to preserving biodiversity and ecosystem functioning. From May 4th to 10th, 2015, an International Workshop on Habitat Fragmentation and Biodiversity Conservation, held at the Thousand Island Lake, Zhejiang, China, discussed threats to biodiversity in fragmented landscapes and how Fragmentation research can identify and help mitigate these threats. To meet these challenges, the Workshop had three goals. The first was to synthesize key findings in Fragmentation science. Second was to identify important remaining research questions concerning the relationships between Habitat Fragmentation, biodiversity, and ecosystem functioning at local, regional, and global scales. Finally, we examined the unique roles of field-based Fragmentation experiments in addressing these questions. The Workshop’s findings are relevant to the broader ecological community, and we present them here to stimulate research that will advance landscape ecology and conservation biology.
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rethinking the conceptual foundations of Habitat Fragmentation research
Oikos, 2012Co-Authors: Raphael K. Didham, Valerie Kapos, Robert M. EwersAbstract:Th e conceptual foundations of Habitat Fragmentation research have not kept pace with empirical advances in our understanding of species responses to landscape change, nor with theoretical advances in the wider disciplines of ecology. Th ere is now real debate whether explicit recognition of ‘ Habitat Fragmentation ’ as an over-arching conceptual domain will stimulate or hinder further progress toward understanding and mitigating the eff ects of landscape change. In this paper, we critically challenge the conceptual foundations of the discipline, and attempt to derive an integrated perspective on the best way to advance mechanistic understanding of Fragmentation processes. We depict the inherent assumptions underlying the discipline as a ‘ conceptual phase space ’ of contrasting false dichotomies in Fragmentation ‘ problem space ’ . In our opinion, the key determinant of whether ‘ Habitat Fragmentation ’ can remain a cohesive framework lies in the concept of ‘ interdependence ’ : 1) interdependence of landscape eff ects on species and 2) interdependence of species responses to landscape change. If there is non-trivial interdependence among the various sub-components of Habitat Fragmentation, or non-trivial interdependence among species responses to landscape change, then there will be real heuristic value in ‘ Habitat Fragmentation ’ as a single conceptual domain. At present, the current paradigms entrenched in the Fragmentation literature are implicitly founded on strict independence of landscape eff ects (e.g. the debate about the independent eff ects of Habitat loss versus Fragmentation per se) and strict independence of species responses (e.g. the individualistic species response models underpinning landscape continuum models), despite compelling evidence for interdependence in both eff ects and responses to Fragmentation. We discuss how strong ‘ interdependence ’ of eff ects and responses challenges us to rethink longheld views, and re-cast the conceptual foundations of Habitat Fragmentation in terms of spatial context-dependence in the eff ects of multiple interacting spatial components of Fragmentation, and community context-dependence in the responses of multiple interacting species to landscape change.
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eLS - Ecological Consequences of Habitat Fragmentation
Encyclopedia of Life Sciences, 2010Co-Authors: Raphael K. DidhamAbstract:Habitat Fragmentation is the process by which Habitat loss results in the division of large, continuous Habitats into smaller, more isolated remnants. Thousands of scientific studies now show unequivocal evidence for the impacts of patch area, edge effects, patch shape complexity, isolation and landscape matrix contrast on community structure and ecosystem functioning. However, striking disparities in the results of these studies have raised considerable debate about the relative importance of different mechanisms underlying Fragmentation effects, and even about the utility of the ‘Fragmentation’ concept in general. Resolution of this debate lies in clear discrimination of direct versus indirect causal relationships among patch and landscape variables. The most important recent advances in our understanding of Fragmentation effects all stem from recognition of strong context-dependence in ecosystem responses, including spatial context-dependence at multiple scales, time-lagged population declines, trait-dependent species responses and synergistic interactions between Fragmentation and other components of global environmental change. Key Concepts: Habitat Fragmentation is an umbrella term describing the complete process by which Habitat loss results in the division of large, continuous Habitats into a greater number of smaller patches of lower total area, isolated from each other by a matrix of dissimilar Habitats, and is not just the pattern of spatial arrangement of remaining Habitat. Habitat loss and Habitat Fragmentation are not independent drivers of ecological change – Habitat loss acts via the change in Habitat arrangement, not independently of it. Habitat Fragmentation is a landscape-level phenomenon, and patch-level processes (patch area, edge effects and patch shape complexity) can only be understood within a landscape context (isolation and matrix structure). A dominant effect of increasing Habitat loss is a reduction in patch area, with resulting declines in population density and species richness, and significant alterations to community composition, species interactions and ecosystem functioning. The Habitat edge is not a discrete boundary line around a patch, it is a fuzzy three-dimensional zone that straddles both sides of the patch-matrix boundary, and the intensity of edge influence may be variable and asymmetrical around the physical vegetation boundary. Quantification of edge impact requires explicit discrimination of two distinct components of edge influence: edge extent (i.e. the distance over which a statistical difference in response can be detected between the matrix and the patch) and edge magnitude (i.e. the degree of difference in response between the patch interior and the matrix interior). Increasing patch shape complexity substantially reduces the availability of ‘core’ Habitat area unaffected by edge effects. Patch isolation reduces population connectivity and reduces the probability of population persistence, but geographic isolation is not an absolute quantity and can only be interpreted in the light of matrix permeability, the dispersal traits of the species in question and the time-scale over which effects might become apparent. Matrix quality and surrounding landscape composition have a dominant influence on population dynamics, species diversity and ecosystem processes in Habitat patches. Habitat Fragmentation interacts strongly with other components of global environmental change, including species invasions, land-use intensification and climate change. Keywords: connectivity; context-dependence; edge effects; Habitat area; Habitat Fragmentation; Habitat loss; isolation; landscape structure; matrix contrast; patch shape
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Habitat Fragmentation: panchreston or paradigm?
Trends in ecology & evolution, 2007Co-Authors: Robert M. Ewers, Raphael K. DidhamAbstract:There is no doubt that ‘Habitat Fragmentation’ has become a broad umbrella term encompassing a wide variety of patterns and processes within landscapes. David Lindenmayer and Joern Fischer [1xTackling the Habitat Fragmentation panchreston. Lindenmayer, D.B. and Fischer, J. Trends Ecol. Evol. 2007; 22: 127–132Abstract | Full Text | Full Text PDF | PubMed | Scopus (141)See all References[1] argue that the term is now so vague that it has become a panchreston that fuels unproductive scientific debates and hampers efforts to understand and mitigate the impacts of landscape change on biodiversity. We agree that Fragmentation could mean different things to different people, but we disagree that this imbues the term with limited value. As with another (in)famous umbrella term ‘biodiversity’, there is real heuristic value in explicit recognition of an over-arching domain that incorporates multiple interacting patterns and processes. The term ‘biodiversity’ could easily be labelled a panchreston, but is still widely used in its broadest conceptual sense, despite years of similar debates over inconsistent use of terminology, definitional issues and the variety of mechanistic processes that might explain patterns of ‘biodiversity’ at all levels of biological organization across multiple spatial and temporal scales [2xBiodiversity – the appreciation of different thought styles and values helps to clarify the term. Mayer, P. Rest. Ecol. 2006; 14: 105–111Crossref | Scopus (25)See all References, 3xWhat does ‘biodiversity’ mean – scientific problem or convenient myth?. Ghilarov, A. Trends Ecol. Evol. 1996; 11: 304–306Abstract | Full Text PDF | PubMed | Scopus (32)See all References].Habitat Fragmentation is not a set of disjoint processes that should be artificially separated into themes to be studied in isolation from one another. This is because there are strong and ubiquitous inter-correlations among Habitat area, increasing Habitat subdivision, creation of edges, altered connectivity among patches and changes in Habitat quality [4xEffects of Habitat Fragmentation on biodiversity. Fahrig, L. Annu. Rev. Ecol. Evol. Syst. 2003; 34: 487–515CrossrefSee all References, 5xConfounding factors in the detection of species responses to Habitat Fragmentation. Ewers, R.M. and Didham, R.K. Biol. Rev. 2006; 81: 117–142Crossref | PubMed | Scopus (754)See all References] that effectively negate their treatment as independent variables. Habitat Fragmentation also encompasses the existence of interaction effects among the co-varying components of fragmented landscapes. For example, the strength of edge effects is dependent on fragment size [6xSynergistic interactions between edge and area effects in a heavily fragmented landscape. Ewers, R.M. et al. Ecology. 2007; 88: 96–106Crossref | PubMed | Scopus (107)See all References[6], Habitat area effects are dependent on spatial and temporal variability in the surrounding landscape matrix [7xLong-term landscape change and bird abundance in Amazonian rainforest fragments. Stouffer, P.C. et al. Conserv. Biol. 2006; 20: 1212–1223Crossref | PubMed | Scopus (78)See all References[7], and altered species interactions are contingent on multiple species responding to landscape pattern in different ways and at different scales [8xTests of landscape influence: nest predation and brood parasitism in fragmented ecosystems. Tewksbury, J.J. et al. Ecology. 2006; 87: 759–768Crossref | PubMed | Scopus (74)See all References[8]. All of the patterns, processes and consequences of Habitat Fragmentation are interrelated, occur simultaneously and should rightly be drawn together under a single framework. We consider that it is important for authors to continue to frame their studies within the existing conceptual domain of ‘Habitat Fragmentation’. This is not to say that there is no need for researchers to be more precise in their terminology when reporting Fragmentation studies. We wholeheartedly agree with Lindenmayer and Fischer that researchers should be exact when defining the variables they are studying. However, we disagree that the generality of the term ‘Habitat Fragmentation’ has led to it becoming a panchreston. Rather, we suggest that this generality must be maintained to foster the awareness and exchange of data, ideas and information among individuals that, by necessity, focus their research on just one or a handful of the components of fragmented environments.
Péter Batáry - One of the best experts on this subject based on the ideXlab platform.
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responses of insect herbivores and herbivory to Habitat Fragmentation a hierarchical meta analysis
Ecology Letters, 2017Co-Authors: María Rosa Rossetti, Teja Tscharntke, Ramiro Aguilar, Péter BatáryAbstract:Loss and Fragmentation of natural Habitats can lead to alterations of plant-animal interactions and ecosystems functioning. Insect herbivory, an important antagonistic interaction is expected to be influenced by Habitat Fragmentation through direct negative effects on herbivore community richness and indirect positive effects due to losses of natural enemies. Plant community changes with Habitat Fragmentation added to the indirect effects but with little predictable impact. Here, we evaluated Habitat Fragmentation effects on both herbivory and herbivore diversity, using novel hierarchical meta-analyses. Across 89 studies, we found a negative effect of Habitat Fragmentation on abundance and species richness of herbivores, but only a non-significant trend on herbivory. Reduced area and increased isolation of remaining fragments yielded the strongest effect on abundance and species richness, while specialist herbivores were the most vulnerable to Habitat Fragmentation. These Fragmentation effects were more pronounced in studies with large spatial extent. The strong reduction in herbivore diversity, but not herbivory, indicates how important common generalist species can be in maintaining herbivory as a major ecosystem process.
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Responses of insect herbivores and herbivory to Habitat Fragmentation: a hierarchical meta‐analysis
Ecology letters, 2017Co-Authors: María Rosa Rossetti, Teja Tscharntke, Ramiro Aguilar, Péter BatáryAbstract:Loss and Fragmentation of natural Habitats can lead to alterations of plant-animal interactions and ecosystems functioning. Insect herbivory, an important antagonistic interaction is expected to be influenced by Habitat Fragmentation through direct negative effects on herbivore community richness and indirect positive effects due to losses of natural enemies. Plant community changes with Habitat Fragmentation added to the indirect effects but with little predictable impact. Here, we evaluated Habitat Fragmentation effects on both herbivory and herbivore diversity, using novel hierarchical meta-analyses. Across 89 studies, we found a negative effect of Habitat Fragmentation on abundance and species richness of herbivores, but only a non-significant trend on herbivory. Reduced area and increased isolation of remaining fragments yielded the strongest effect on abundance and species richness, while specialist herbivores were the most vulnerable to Habitat Fragmentation. These Fragmentation effects were more pronounced in studies with large spatial extent. The strong reduction in herbivore diversity, but not herbivory, indicates how important common generalist species can be in maintaining herbivory as a major ecosystem process.