Consequences of forest fragmentation for the dynamics of bird populations: conceptual issues and the evidence

Rolstad, Jørund

doi:10.1016/b978-0-12-284120-0.50013-9

Cited by 84 publications

(105 citation statements)

References 48 publications

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“…Species that may once have conformed to a metapopulation or refuge model cannot now conform, because of the greatly modified landscape that faces them (see May 1991). Even birds, which would seem to be affected much less by increasing isolation of fragments than other vertebrates (see M0ller 1987, Rolstad 1991, can succumb to drastic changes in habitat structure at the landscape and regional levels (see Diamond 1984, McCollin 1993. One possible consequence of the different kind and degree of fragmentation that scrub species currently face is that some of the species that have relatively high abundances in relatively small scrubs may not be flourishing there.…”

Section: Discussionmentioning

confidence: 99%

“…We measured 13 potentially important environmental attributes of each scrub (McCoy and Mushinsky 1994; also see Adler and Wilson 1985, Freemark and Merriam 1986, Rolstad 1991, Bolger et al 1997. Complete tabulations of data for these attributes are in McCoy and and Mushinsky and McCoy (1995).…”

Section: Study Sitesmentioning

confidence: 99%

“…Many of the attributes are intercorrelated for the 16 scrubs, and larger scrubs differ from smaller scrubs in a variety of ways (McCoy and Mushinsky 1994, Table 2; see Rolstad 1991, Saunders et al 1991. Larger scrubs are surrounded by upland habitat more often, surrounded by less land that is disturbed, surrounded by more kinds of habitats, and less prone to reduction in area over the past 40-60 yr. As well, rosemary tends to be relatively better represented in larger scrubs.…”

Section: Study Sitesmentioning

confidence: 99%

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Habitat Fragmentation and the Abundances of Vertebrates in the Florida Scrub

McCoy

Mushinsky

1999

Ecology

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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.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology.Abstract. Based on presence/absence of species, we proposed previously that large fragments of the Florida sand pine scrub habitat do not possess greater conservation value for vertebrates than do archipelagos of small and medium-sized fragments. We reexamined the values of fragments of different sizes, based this time on abundances of species. We asked whether abundances tend to decrease with decreasing scrub size or are more strongly related to other scrub attribute(s).We censused vertebrates with trap arrays and by direct observation, and we measured 13 potentially important environmental attributes related to area, isolation, and habitat structure in 16 scrubs distributed along the Lake Wales Ridge of central Florida. We correlated abundance of species with the 13 attributes. We calculated the evenness of relative abundance distributions and grouped scrubs based on the shapes of relative abundance distributions. We determined whether or not members of different groups of scrubs possessed different values for any attribute. Finally, we examined both densities of individuals and dispersions of species among large, medium, and small scrubs.Abundance was related to many of the attributes. Abundances of 11 of 18 species were correlated positively with area. Percentage of variation explained by area generally was low, and several of the rare species apparently maintain relatively large populations in small scrubs. Abundances of five species were correlated negatively with measures of isolation. Abundances of three species were correlated both positively and negatively with measures of habitat structure. Environmental attributes related to isolation and habitat structure were correlated most strongly with both evenness and groupings of relative abundance distributions. Total density of individuals (i.e., numbers of captures per trap array) could not be shown to differ among scrubs of different sizes. Individually, the species that reached their highest densities in relatively small scrubs often were the ones considered to be rare. Spatial distributions of species tended to become more homogeneous as area decreased, but the strength of this effect varied among species, perhaps accounting, at least in part, for the different relationships between abundance and area among species.Our results could lead to broad generalizations that seem to be relevant to scrub conservation. For example, because most species are relatively abundant in large scrubs, large scrubs should be selected for reserves over small ones. We suggest, however, that our results actually best serve as a caution ...

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Section: Discussionmentioning

confidence: 99%

Section: Study Sitesmentioning

confidence: 99%

Section: Study Sitesmentioning

confidence: 99%

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Habitat Fragmentation and the Abundances of Vertebrates in the Florida Scrub

McCoy

Mushinsky

1999

Ecology

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“…The same level of fragmentation may result in an environment perceived as "fine-grained" by a larger, more mobile species. In this case each population (even each territory) may extend to multiple fragments [3,4]. The population-level effects in this case are likely to be more complex.…”

Section: Introductionmentioning

confidence: 99%

Implications of Fine-Grained Habitat Fragmentation and Road Mortality for Jaguar Conservation in the Atlantic Forest, Brazil

et al. 2016

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Jaguar (Panthera onca) populations in the Upper Paraná River, in the Brazilian Atlantic Forest region, live in a landscape that includes highly fragmented areas as well as relatively intact ones. We developed a model of jaguar habitat suitability in this region, and based on this habitat model, we developed a spatially structured metapopulation model of the jaguar populations in this area to analyze their viability, the potential impact of road mortality on the populations' persistence, and the interaction between road mortality and habitat fragmentation. In more highly fragmented populations, density of jaguars per unit area is lower and density of roads per jaguar is higher. The populations with the most fragmented habitat were predicted to have much lower persistence in the next 100 years when the model included no dispersal, indicating that the persistence of these populations are dependent to a large extent on dispersal from other populations. This, in turn, indicates that the interaction between road mortality and habitat fragmentation may lead to source-sink dynamics, whereby populations with highly fragmented habitat are maintained only by dispersal from populations with less fragmented habitat. This study demonstrates the utility of linking habitat and demographic models in assessing impacts on species living in fragmented landscapes.

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“…In the context of biodiversity indicators, landscape content obviously in uences the distribution of species in as much as their occurrence is restricted to areas of suitable habitat. In addition, aspects of landscape structure have been shown to in uence the occurrence of several species (Merriam 1988, Opdam 1990, Rolstad 1991, Forman 1995, Hanski 1997. However, in order to use landscape information as a surrogate for biodiversity information, there are a number of important questions to be answered.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneity as a measure of spatial pattern for monitoring agricultural landscapes

Fjellstad¹,

Dramstad²,

Strand³

et al. 2001

Norsk Geografisk Tidsskrift

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The Norwegian monitoring programme for agricultural landscapes is a sample-based programme that aims to document the current state and patterns of change in the agricultural landscape for the entire country. For this broad geographica l coverage an indicato r approach is the most cost-effective methodology . Landscape metrics are used as indicator s in the monitoring programme based on the assumed importance of landscape compositio n and spatial pattern for a number of countrysid e interests. However, althoug h indicator s have been used successfully over a long period of time in various disciplines , their use in landscape monitoring is relatively new and there is little empirical data with which to assess their validity. This paper provides information on the performance of landscape diversity and landscape heterogeneit y indices as estimated by speci c biodiversity measures. Preliminary results show increasing numbers of breeding bird species and numbers of vascular plant species with increasing landscape diversity and heterogeneity , two indices that capture information on landscape content and structure. Overall, the heterogeneity index provided a better surrogate for species richness than the diversity index.

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Consequences of forest fragmentation for the dynamics of bird populations: conceptual issues and the evidence

Cited by 84 publications

References 48 publications

Habitat Fragmentation and the Abundances of Vertebrates in the Florida Scrub

Habitat Fragmentation and the Abundances of Vertebrates in the Florida Scrub

Implications of Fine-Grained Habitat Fragmentation and Road Mortality for Jaguar Conservation in the Atlantic Forest, Brazil

Heterogeneity as a measure of spatial pattern for monitoring agricultural landscapes

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