Habitat fragmentation and extinction thresholds on fractal landscapes

Hill, M. Forrest; Caswell, Hal

doi:10.1046/j.1461-0248.1999.22061.x

Cited by 140 publications

(135 citation statements)

References 20 publications

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“…The majority of metapopulation studies predict that ephemeral or small habitat patches have a negative effect on metapopulation persistence (Lande 1987;Tilman et al 1994;Bascompte and Solé 1996;Gyllenberg and Hanski 1997;Hill and Caswell 1999). These predictions, however, are largely based on the assumption that disturbances and dispersal/colonization dynamics are uncorrelated (Keymer et al 2000;Amarasekare and Possingham 2001;DeWoody 2005;Xu et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Metapopulation Dynamics on Ephemeral Patches

Reigada

Schreiber

Altermatt

et al. 2015

The American Naturalist

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Online enhancements: appendixes.abstract: A challenge for conservation management is to understand how population and habitat dynamics interact to affect species persistence. In real landscapes, timing and duration of disturbances can vary, and species' responses to habitat changes will depend on how timing of dispersal and reproduction events relate to the landscape temporal structure. For instance, increasing disturbance frequency may promote extinction of species that are unable to appropriately time their reproduction in an ever-changing habitat and favor species that are able to track habitat changes. We developed a mathematical model to compare the effects of pulsed dispersal, initiated by shifts in habitat quality, with temporally continuous dispersal. We tested the effects of habitat (and population) turnover rates on metapopulation establishment, persistence, and long-term patch occupancy. Pulsed dispersal reduced patch occupancy and metapopulation longevity when habitat patches are relatively permanent. In such cases, demographic extinction was the primary form of local extinction. Conversely, when habitat patches are short-lived and new ones are frequently formed, pulsed dispersal promoted rapid colonization, increased occupancy, and prolonged metapopulation persistence. Our results show that species responsiveness to habitat disturbance is critical to metapopulation persistence, having profound implications for the species likely to persist in landscapes with altered disturbance regimes.

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Section: Discussionmentioning

confidence: 99%

Metapopulation Dynamics on Ephemeral Patches

Reigada

Schreiber

Altermatt

et al. 2015

The American Naturalist

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“…These landscape thresholds have important consequences for species persistence in fragmented landscapes. Most of the recent advances in our understanding of landscape thresholds have stemmed from the use of metapopulation models that describe the landscape as a mosaic of patches, and focus on the balance between colonisation and extinction rates (Hill & Caswell, 1999). A simple, but important observation is that populations will not occupy all available sites at any given point in time, and that site occupancy depends greatly on the degree of connectivity in the landscape (Bascompte & Sole, 1996).…”

Section: Isolationmentioning

confidence: 99%

Confounding factors in the detection of species responses to habitat fragmentation

2005

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Habitat loss has pervasive and disruptive impacts on biodiversity in habitat remnants. The magnitude of the ecological impacts of habitat loss can be exacerbated by the spatial arrangement -or fragmentation -of remaining habitat. Fragmentation per se is a landscape-level phenomenon in which species that survive in habitat remnants are confronted with a modified environment of reduced area, increased isolation and novel ecological boundaries. The implications of this for individual organisms are many and varied, because species with differing life history strategies are differentially affected by habitat fragmentation. Here, we review the extensive literature on species responses to habitat fragmentation, and detail the numerous ways in which confounding factors have either masked the detection, or prevented the manifestation, of predicted fragmentation effects.Large numbers of empirical studies continue to document changes in species richness with decreasing habitat area, with positive, negative and no relationships regularly reported. The debate surrounding such widely contrasting results is beginning to be resolved by findings that the expected positive species-area relationship can be masked by matrix-derived spatial subsidies of resources to fragment-dwelling species and by the invasion of matrix-dwelling species into habitat edges. Significant advances have been made recently in our understanding of how species interactions are altered at habitat edges as a result of these changes. Interestingly, changes in biotic and abiotic parameters at edges also make ecological processes more variable than in habitat interiors. Individuals are more likely to encounter habitat edges in fragments with convoluted shapes, leading to increased turnover and variability in population size than in fragments that are compact in shape. Habitat isolation in both space and time disrupts species distribution patterns, with consequent effects on metapopulation dynamics and the genetic structure of fragment-dwelling populations. Again, the matrix habitat is a strong determinant of fragmentation effects within remnants because of its role in regulating dispersal and dispersalrelated mortality, the provision of spatial subsidies and the potential mediation of edge-related microclimatic gradients.We show that confounding factors can mask many fragmentation effects. For instance, there are multiple ways in which species traits like trophic level, dispersal ability and degree of habitat specialisation influence specieslevel responses. The temporal scale of investigation may have a strong influence on the results of a study, with short-term crowding effects eventually giving way to long-term extinction debts. Moreover, many fragmentation effects like changes in genetic, morphological or behavioural traits of species require time to appear. By contrast, synergistic interactions of fragmentation with climate change, human-altered disturbance regimes, species interactions and other drivers of population decline may magnify the impacts...

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“…Hill & Caswell, 1999;Bakkenes et al, 2002;Guisan et al, 2002) and GAMs are increasingly used (Yee & Mitchell, 1991;Frescino et al, 2001;Guisan et al, 2002;Thuiller et al, 2006a), whereas GBM (Friedman et al, 2000) has only recently been used (Leathwick et al, 2006;Broennimann et al, 2007;Pearman et al, 2008) and implemented in BIOMOD (Leathwick et al, 2006;Thuiller et al, 2006b). GBM was ranked as the best performing techniques in a recent large comparative analysis by Elith et al (2006).…”

Section: Sdms and Their Projectionsmentioning

confidence: 99%

Climate change and plant distribution: local models predict high‐elevation persistence

Randin¹,

Engler²,

Normand

et al. 2009

Global Change Biology

478

461

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Mountain ecosystems will likely be affected by global warming during the 21st century, with substantial biodiversity loss predicted by species distribution models (SDMs). Depending on the geographic extent, elevation range, and spatial resolution of data used in making these models, different rates of habitat loss have been predicted, with associated risk of species extinction. Few coordinated across-scale comparisons have been made using data of different resolutions and geographic extents. Here, we assess whether climate change-induced habitat losses predicted at the European scale (10 Â 10 0 grid cells) are also predicted from local-scale data and modeling (25 m Â 25 m grid cells) in two regions of the Swiss Alps. We show that local-scale models predict persistence of suitable habitats in up to 100% of species that were predicted by a European-scale model to lose all their suitable habitats in the area. Proportion of habitat loss depends on climate change scenario and study area. We find good agreement between the mismatch in predictions between scales and the fine-grain elevation range within 10 Â 10 0 cells. The greatest prediction discrepancy for alpine species occurs in the area with the largest nival zone. Our results suggest elevation range as the main driver for the observed prediction discrepancies. Local-scale projections may better reflect the possibility for species to track their climatic requirement toward higher elevations.

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Habitat fragmentation and extinction thresholds on fractal landscapes

Cited by 140 publications

References 20 publications

Metapopulation Dynamics on Ephemeral Patches

Metapopulation Dynamics on Ephemeral Patches

Confounding factors in the detection of species responses to habitat fragmentation

Climate change and plant distribution: local models predict high‐elevation persistence

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