共查询到20条相似文献,搜索用时 31 毫秒
1.
Fernando R. Silva Thiago A. L. Oliveira James P. Gibbs Denise C. Rossa-Feres 《Landscape Ecology》2012,27(1):87-96
Amphibians are an imperiled group of vertebrate animals that typically have biphasic life histories involving a shift from
aquatic larval habitats to terrestrial adult habitats. Habitat loss is the greatest threat to amphibians and the importance
of the spatial configuration of terrestrial and breeding habitats upon the landscape in determining amphibian persistence
is poorly known. The information gap is particularly acute in tropical landscapes that simultaneously host the greatest and
most imperiled amphibian fauna on Earth. We installed 125 artificial ponds at different distances from forest fragments embedded
in an agricultural matrix in southeastern Brazil. Constructed ponds attracted 13 anuran species; ponds at the forest fragment-matrix
transition hosted a greater abundance and higher species richness of frogs and toads than those installed either far from
or well within forest fragments. Forest fragments larger than 70 ha in agricultural areas harbored more individuals than smaller
fragments. Our results indicate that landscape configuration has an important influence on frog and toad distribution and
abundance in tropical agricultural landscapes and we suggest guidelines for maintaining favorable configurations of aquatic
and terrestrial habitats for conserving this rich and imperiled species suite. 相似文献
2.
Contemporary landscape ecology continues to explore the causes and consequences of landscape heterogeneity across a range of scales, and demands for the scientific underpinnings of landscape planning and management still remains high. The spatial distribution of resources can be a key element in determining habitat quality, and that in turn is directly related to the level of heterogeneity in the system. In this sense, forest habitat mosaics may be more affected by lack of heterogeneity than by structural fragmentation. Nonetheless, increasing spatial heterogeneity at a given spatial scale can also decrease habitat patch size, with potential negative consequences for specialist species. Such dual effect may lead to hump-backed shape relationships between species diversity and heterogeneity, leading to three related assumptions: (i) at low levels of heterogeneity, an increase in heterogeneity favours local and regional species richness, (ii) there is an optimum heterogeneity level at which a maximum number of species is reached, (iii) further increase in spatial heterogeneity has a negative effect on local and regional species richness, due to increasing adverse effects of habitat fragmentation. In this study, we investigated the existence of a hump-shaped relationship between local plant species richness and increasing forest landscape heterogeneity on a complex mosaic in the French Alps. Forest landscape heterogeneity was quantified with five independent criteria. We found significant quadratic relationships between local forest species richness and two heterogeneity criteria indicators, showing a slight decrease of forest species richness at very high heterogeneity levels. Species richness–landscape heterogeneity relationships varied according to the heterogeneity metrics involved and the type of species richness considered. Our results support the assumption that intermediate levels of heterogeneity may support more species than very high levels of heterogeneity, although we were not able to conclude for a systematic negative effect of very high levels of heterogeneity on local plant species richness. 相似文献
3.
Bird assemblages in forest fragments within Mediterranean mosaics created by wild fires 总被引:1,自引:1,他引:0
The role of habitat heterogeneity as a key factor in determining species pools in habitat mosaics has been acknowledged, but we still know little on the relative importance of the different ecological processes acting within such complex landscapes. We compared species richness and distribution in forest fragments imbedded in shrub-lands to those in continuous forests or in continuous shrublands. We examined the consistency of our data with the predictions of two hypotheses: 1) the Habitat fragmentation hypothesis which states that fragmentation has negative effects on the species from the original continuous habitat; 2) the Habitat supplementation /complementation hypothesis which stipulates that the presence of a matrix habitat around the fragments will mitigate negative effects on the species from the original habitat (supplementation) or allow the presence of species that depend on the presence of both the fragment and matrix habitats (complementation). We show that: 1) species richness in forest fragments did not differ from species richness in segments of continuous forests of equal area; 2) the bird community of forest fragments got impoverished in some forest species but a higher proportion of species common in continuous forests were not affected by fragmentation; 3) fragment communities had a significant proportion of common species that were scarce in, or absent from both continuous forests and shrublands. While, a few forest species supported predictions from the fragmentation hypothesis, occurrence patterns observed in several other species were consistent with either the supplementation or the complementation hypotheses. Our results suggest that there is no single hypothesis that properly captures the consequences of a shift from continuous forests to a mosaic of forest fragments and shrublands and that different ecological mechanisms act in conjunction to determine species pools in habitat mosaics. Habitat heterogeneity at a local scale appears a key factor in maintaining bird diversity in fire driven Mediterranean landscapes. 相似文献
4.
Context
Habitat loss and habitat fragmentation negatively affect amphibian populations. Roads impact amphibian species through barrier effects and traffic mortality. The landscape variable ‘accessible habitat’ considers the combined effects of habitat loss and roads on populations.Objectives
The aim was to test whether accessible habitat was a better predictor of amphibian species richness than separate measures of road effects and habitat loss. I assessed how accessible habitat and local habitat variables determine species richness and community composition.Methods
Frog and tadpole surveys were conducted at 52 wetlands in a peri-urban area of eastern Australia. Accessible habitat was delineated using a highway. Regressions were used to examine relationships between species richness and eleven landscape and local habitat variables. Redundancy analysis was used to examine relationships between community composition and accessible habitat and local habitat variables.Results
Best-ranked models of species richness included both landscape and local habitat variables. There were positive relationships between species richness and accessible habitat and distance to the highway, and uncertain relationships with proportion cover of native vegetation and road density. There were negative relationships between species richness and concreted wetlands and wetland electrical conductivity. Four species were positively associated with accessible habitat, whereas all species were negatively associated with wetland type.Conclusions
Barrier effects caused by the highway and habitat loss have negatively affected the amphibian community. Local habitat variables had strong relationships with species richness and community composition, highlighting the importance of both availability and quality of habitat for amphibian conservation near major roads.5.
Howell Christine A. Latta Steven C. Donovan Therese M. Porneluzi Paul A. Parks Geoffrey R. Faaborg John 《Landscape Ecology》2000,15(6):547-562
We examine the influence of both local habitat and landscape variables on avian species abundance at forested study sites situated within fragmented and contiguous landscapes. The study was conducted over a six year period (1991–1996) at 10 study sites equally divided between the heavily forested Missouri Ozarks and forest fragments in central Missouri. We found greater species richness and diversity in the fragments, but there was a higher percentage of Neotropical migrants in the Ozarks. We found significant differences in the mean number of birds detected between the central Missouri fragments and the unfragmented Ozarks for 15 (63%) of 24 focal species. We used stepwise regression to determine which of 12 local vegetation variables and 4 landscape variables (forest cover, core area, edge density, and mean patch size) accounted for the greatest amount of variation in abundance for 24 bird species. Seven species (29%) were most sensitive to local vegetation variables, while 16 species (67%) responded most strongly to one of four landscape variables. Landscape variables are significant predictors of abundance for many bird species; resource managers should consider multiple measures of landscape sensitivity when making bird population management decisions.Order of first two authors decided by coin toss 相似文献
6.
Acknowledgment that the matrix matters in conserving wildlife in human-modified landscapes is increasing. However, the complex
interactions of habitat loss, habitat fragmentation, habitat condition and land use have confounded attempts to disentangle
the relative importance of properties of the landscape mosaic, including the matrix. To this end, we controlled for the amount
of remnant forest habitat and the level of fragmentation to examine mammal species richness in human-modified landscapes of
varying levels of matrix development intensity and patch attributes. We postulated seven alternative models of various patch
habitat, landscape and matrix influences on mammal species richness and then tested these models using generalized linear
mixed-effects models within an information theoretic framework. Matrix attributes were the most important determinants of
terrestrial mammal species richness; matrix development intensity had a strong negative effect and vegetation structural complexity
of the matrix had a strong positive effect. Distance to the nearest remnant forest habitat was relatively unimportant. Matrix
habitat attributes are potentially a more important indicator of isolation of remnant forest patches than measures of distance
to the nearest patch. We conclude that a structurally complex matrix within a human-modified landscape can provide supplementary
habitat resources and increase the probability of movement across the landscape, thereby increasing mammal species richness
in modified landscapes. 相似文献
7.
The landscape matrix modifies the effect of habitat fragmentation in grassland butterflies 总被引:1,自引:0,他引:1
Erik ?ckinger Karl-Olof Bergman Markus Franzén Tomá? Kadlec Jochen Krauss Mikko Kuussaari Juha P?yry Henrik G. Smith Ingolf Steffan-Dewenter Riccardo Bommarco 《Landscape Ecology》2012,27(1):121-131
The landscape matrix is suggested to influence the effect of habitat fragmentation on species richness, but the generality
of this prediction has not been tested. Here, we used data from 10 independent studies on butterfly species richness, where
the matrix surrounding grassland patches was dominated by either forest or arable land to test if matrix land use influenced
the response of species richness to patch area and connectivity. To account for the possibility that some of the observed
species use the matrix as their main or complementary habitat, we analysed the effects on total species richness and on the
richness of grassland specialist and non-specialist (generalists and specialists on other habitat types) butterflies separately.
Specialists and non-specialists were defined separately for each dataset. Total species richness and the richness of grassland
specialist butterflies were positively related to patch area and forest cover in the matrix, and negatively to patch isolation.
The strength of the species-area relationship was modified by matrix land use and had a slope that decreased with increasing
forest cover in the matrix. Potential mechanisms for the weaker effect of grassland fragmentation in forest-dominated landscapes
are (1) that the forest matrix is more heterogeneous and contains more resources, (2) that small grassland patches in a matrix
dominated by arable land suffer more from negative edge effects or (3) that the arable matrix constitutes a stronger barrier
to dispersal between populations. Regardless of the mechanisms, our results show that there are general effects of matrix
land use across landscapes and regions, and that landscape management that increases matrix quality can be a complement to
habitat restoration and re-creation in fragmented landscapes. 相似文献
8.
Matrix quality affects probability of persistence in habitat patches in landscape simulation models while empirical studies
show that both urban and agricultural land uses affect forest birds. However, due to the fact that forest bird abundance and
species richness can be strongly influenced by local habitat factors, it is difficult to analyze matrix effects without confounding
effects from such factors. Given this, our objectives were to (1) relate human-dominated land uses to forest bird abundance
and species richness without confounding effects from other factors; (2) determine the scale at which forest birds respond
to the matrix; and (3) identify whether certain bird migratory strategies or habitat associations vary in richness or abundance
as a function of urban and agriculture land uses. Birds were surveyed at a single point count site 100 m from the edge of
23 deciduous forest patches near Ottawa, Ontario. Land uses surrounding each patch were measured within increasingly large
circles from 200 to 5000 m radius around the bird survey site. Regression results suggest that effects of urban and agricultural
land uses on forest birds (1) are not uniformly positive or negative, (2) can occur at different spatial scales, and (3) differentially
affect certain groups of species. In general, agriculture appeared to affect species at a broad spatial scale (within 5 km),
while urban land use had an impact at both a narrower spatial scale (within 1.8 km) and at the broad scale. Neotropical and
short distance migrant birds seemed to be the most sensitive to land use intensification within the matrix. Limiting urban
land use within approximately 200–1800 m of forest patches would be beneficial for Neotropical migrant birds, which are species
of growing conservation concern in temperate North America. 相似文献
9.
Miriam M. Hansbauer Ilse Storch Felix Knauer Stefan Pilz Helmut Küchenhoff Zsolt Végvári Rafael G. Pimentel Jean Paul Metzger 《Landscape Ecology》2010,25(3):407-417
Even among forest specialists, species-specific responses to anthropogenic forest fragmentation may vary considerably. Some
appear to be confined to forest interiors, and perceive a fragmented landscape as a mosaic of suitable fragments and hostile
matrix. Others, however, are able to make use of matrix habitats and perceive the landscape in shades of grey rather than
black-and-white. We analysed data of 42 Chiroxiphia caudata (Blue Manakin), 10 Pyriglena leucoptera (White-shouldered Fire-eye) and 19 Sclerurus scansor (Rufous-breasted Leaftosser) radio-tracked in the Atlantic Rainforest of Brazil between 2003 and 2005. We illustrate how
habitat preferences may determine how species respond to or perceive the landscape structure. We compared available with used
habitat to develop a species-specific preference index for each of six habitat classes. All three species preferred old forest,
but relative use of other classes differed significantly. S. scansor perceived great contrast between old forest and matrix, whereas the other two species perceived greater habitat continuity.
For conservation planning, our study offers three important messages: (1) some forest specialist species are able to persist
in highly fragmented landscapes; (2) some forest species may be able to make use of different anthropogenic habitat types
to various degrees; whereas (3) others are restricted to the remaining forest fragments. Our study suggests species most confined
to forest interiors to be considered as potential umbrella species for landscape-scale conservation planning. 相似文献
10.
Raquel Ribeiro Miguel A. Carretero Neftalí Sillero Gonzalo Alarcos Manuel Ortiz-Santaliestra Miguel Lizana Gustavo A. Llorente 《Landscape Ecology》2011,26(5):673-682
Landscape connectivity is a very recurrent theme in landscape ecology as it is considered pivotal for the long term conservation
of any organism’s populations. Nevertheless, this complex concept is still surrounded by uncertainty and confusion, largely
due to the separation between structural and functional connectivity. Amphibians are the most threatened vertebrates around
the globe, in Europe mostly due to habitat alteration, and to their particular life cycle. Pond breeding amphibians are considered
to be organised in metapopulations, enhancing the importance of landscape connectivity in this group of animals. We sampled
the amphibian species present in two pond groups in Central Western Spain. We applied the graph theory framework to these
two pond networks in order to determine the importance of each pond for the entire network connectivity. We related the pond
importance for connectivity with the species richness present in each pond. We tested if connectivity (partially) determined
the presence of the amphibian species sampled using logistic regression. The results show that the structural connectivity
of the pond network impacts on the amphibian species richness pattern and that the importance of the pond for the connectivity
of the network is an important factor for the presence of some species. Our results, hence, attest the importance of (structural)
landscape connectivity determining the pattern of amphibian (functional) colonization in discrete ponds. 相似文献
11.
We explored the ways in which environmental variation at multiple spatial scales influences the organization of ant species
into local communities. Ground-dwelling ants were sampled in sandhill habitat at 33 locations throughout northern Florida,
USA. Variance partitioning of local, landscape, and regional datasets using partial redundancy analysis indicates that ant
community composition is significantly influenced by environmental variability across all scales of analysis. Habitat generalists
appear to replace habitat specialists at sites with high proportions of matrix habitat in the surrounding landscape. Conversely,
habitat specialists appear to replace habitat generalists at sites with more sandhill habitat in the surrounding landscape
and greater amounts of bare ground locally. Local niche differentiation leading to species-sorting, combined with the effects
of spatially structured dispersal dynamics at landscape scales, may explain this pattern of community structure. Regional
influences on local ant communities were correlated with geographical and environmental gradients at distinct regional scales.
Therefore, local ant communities appear to be simultaneously structured by different processes that occur at separate spatial
scales: local, landscape, and regional scales defined by spatial extent. Our results illustrate the importance of considering
multiscale influences on patterns of organization in ecological communities.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
Juan Luis H. Cardós Isabel Martínez Gregorio Aragón Christopher J. Ellis 《Landscape Ecology》2018,33(10):1757-1768
Context
The anthropocene is characterised by global landscape modification, and the structure of remnant habitats can explain different patterns of species richness. The most pervasive processes of degradation include habitat loss and fragmentation. However, a recovery of modified landscape is occurring in some areas.Objectives
The main goal is to know how lichen and bryophyte epiphytic richness growing on Mediterranean forests is influenced not only by fragments characteristics but also by the structure of the landscape. We introduce a temporal dimension in order to evaluate if the historical landscape structure is relevant for current epiphytic communities.Methods
40 well-preserved forest fragments were selected in a landscape with a large habitat loss over decades, but with a recovery of forest surface in the last 55 years. The most relevant fragment and landscape-scale attributes were considered. Some of the variables were measured in three different years to incorporate a temporal framework.Results
The results showed that variables at fragment scale had a higher influence, whereas variables at the landscape scale were irrelevant. Among all the historical variables analyzed, only the shift in forest fragment size had influence on species richness.Conclusions
Mediterranean forests had suffered fragmentation along centuries. Their epiphytic communities also suffer the hard conditions of Mediterranean climate. Our results indicate that Mediterranean epiphytic communities may be in a threshold since it they will never be similar to those communities existing previous fragmentation process even a recovery habitat occur or, they may require more time to response to this habitat recovery.13.
The effects of habitat fragmentation on species richness and composition have been extensively studied. However, little is known about how fragmentation affects functional diversity patterns. Fragmentation can indeed affect functional diversity directly (e.g. by promoting traits associated to long-distance dispersal when fragment isolation increases) or indirectly (e.g. by decreasing species richness, hence trait diversity, when fragment area decreases). Here, we used structural equation modeling to determine whether factors associated to forest fragmentation, namely area, habitat heterogeneity, spatial isolation and age have a direct effect on forest herb functional diversity. Using occurrence data from 243 forest fragments located in northern France and six plant life-history traits, we estimated species richness and calculated functional diversity in each of these 243 forest fragments. We found that species richness was the primary driver of functional diversity in these fragments, with a strong positive and direct relationship between species richness and functional diversity. Interestingly, both fragment isolation and age had a direct negative effect on functional diversity independent of their effects on species richness. Isolation selected life-history traits associated with long-distance dispersal, while age selected for life-history traits typical of forest habitat specialists. Isolated and/or older forest fragments are thus at greater risk of local species and functional extinctions, and hence making these forest fragments particularly vulnerable to future global changes. 相似文献
14.
The rapid expansion of the world’s urban population is a major driver of contemporary landscape change and ecosystem modification.
Urbanisation destroys, degrades and fragments native ecosystems, replacing them with a heterogeneous matrix of urban development,
parks, roads, and isolated remnant fragments of varying size and quality. This presents a major challenge for biodiversity
conservation within urban areas. To make spatially explicit decisions about urban biodiversity conservation actions, urban
planners and managers need to be able to separate the relative influence of landscape composition and configuration from patch
and local (site)-scale variables for a range of fauna species. We address this problem using a hierarchical landscape approach
for native, terrestrial reptiles and small mammals living in a fragmented semi-urban landscape of Brisbane, Australia. Generalised
linear modelling and hierarchical partitioning analysis were applied to quantify the relative influence of landscape composition
and configuration, patch size and shape, and local habitat composition and structure on the species’ richness of mammal and
reptile assemblages. Landscape structure (composition and configuration) and local-scale habitat structure variables were
found to be most important for influencing reptile and mammal assemblages, although the relative importance of specific variables
differed between reptile and mammal assemblages. These findings highlight the importance of considering landscape composition
and configuration in addition to local habitat elements when planning and/or managing for the conservation of native, terrestrial
fauna diversity in urban landscapes. 相似文献
15.
Ricardo Rocha Milou Groenenberg Paulo E. D. Bobrowiec Mar Cabeza Jorge M. Palmeirim Christoph F. J. Meyer 《Landscape Ecology》2017,32(1):31-45
Context
Habitat loss, fragmentation and degradation are widespread drivers of biodiversity decline. Understanding how habitat quality interacts with landscape context, and how they jointly affect species in human-modified landscapes, is of great importance for informing conservation and management.Objectives
We used a whole-ecosystem manipulation experiment in the Brazilian Amazon to investigate the relative roles of local and landscape attributes in affecting bat assemblages at an interior-edge-matrix disturbance gradient.Methods
We surveyed bats in 39 sites, comprising continuous forest (CF), fragments, forest edges and intervening secondary regrowth. For each site, we assessed vegetation structure (local-scale variable) and, for five focal scales, quantified habitat amount and four landscape configuration metrics.Results
Smaller fragments, edges and regrowth sites had fewer species and higher levels of dominance than CF. Regardless of the landscape scale analysed, species richness and evenness were mostly related to the amount of forest cover. Vegetation structure and configurational metrics were important predictors of abundance, whereby the magnitude and direction of response to configurational metrics were scale-dependent. Responses were ensemble-specific with local-scale vegetation structure being more important for frugivorous than for gleaning animalivorous bats.Conclusions
Our study indicates that scale-sensitive measures of landscape structure are needed for a more comprehensive understanding of the effects of fragmentation on tropical biota. Although forest fragments and regrowth habitats can be of conservation significance for tropical bats our results further emphasize that primary forest is of irreplaceable value, underlining that their conservation can only be achieved by the preservation of large expanses of pristine habitat.16.
Megan J. Brady Clive A. McAlpine Craig J. Miller Hugh P. Possingham Greg S. Baxter 《Landscape Ecology》2009,24(7):879-891
The matrix is an important element of landscape mosaics that influences wildlife indirectly through its influence on habitat,
and directly, if they live in or move through it. Therefore, to quantify and manage habitat quality for wildlife in modified
landscapes, it is necessary to consider the characteristics of both patch and matrix elements of the whole landscape mosaic.
To isolate matrix effects from the often simultaneous and confounding influence of patch and landscape characteristics, we
identified nineteen 500 m radius landscapes in southeast Queensland, Australia with similar remnant forest patch attributes,
habitat loss, and fragmentation, but exhibiting a marked gradient from rural through high-density suburban development of
the matrix, quantified by a weighted road-length metric. We measured habitat disturbance, structure, and floristics in patch
core, patch edge and matrix landscape elements to characterise how landscape habitat quality changes for small mammals. Correlation
analyses identified that with increased matrix development intensity, human disturbance of core sites increased, predators
and exotic plant species richness in matrix sites increased, and structural complexity (e.g. logs and stumps) in the matrix
decreased. Ordination analyses showed landscape elements were most similar in habitat structure and floristics at low to moderate
levels of matrix development, suggesting enhanced landscape habitat quality. Matrix development intensity was not, however,
the greatest source of overall variation of habitat throughout landscapes. Many variables, such as landholder behaviour, complicate
the relationship. For enhanced conservation outcomes the matrix needs to be managed to control disturbances and strategically
plan for matrix habitat retention and restoration. 相似文献
17.
Heike Kappes Kurt Jordaens Frederik Hendrickx Jean-Pierre Maelfait Luc Lens Thierry Backeljau 《Landscape Ecology》2009,24(5):685-697
Habitat fragmentation is a major cause for species loss, but its effect on invertebrates with low active dispersal power,
like terrestrial gastropods, has rarely been studied. Such species can not cross a hostile habitat matrix, for which the predictions
of island theory, such as positive relations between species richness and patch size, should apply. In order to test this
prediction, we studied gastropod species diversity by assessing gastropod assemblage characteristics from 35 sites in 19 fragments
of deciduous old-growth forests in the Lower Rhine Embayment, Germany. Assemblages differed between larger (≥700 ha) and smaller
forests (<400 ha), those of large forests held a higher percentage of forest species. Although α-diversity was similar between
the two forest size classes, small forests often comprised matrix species, resulting in a higher β-diversity. Edge effects
on the species richness of matrix species were noticeable up to 250 m into the forest. Hierarchical partitioning revealed
that distance to disturbances (external edge, internal edges like roads) explained most assemblage variables, whereas forest
size and woodland cover within a 1 km radius from the sites explained only a few assemblage variables. Densities of two forest-associated
species, Discus rotundatus and Arion fuscus, decreased with forest size. Yet, forest size was positively correlated with richness of typical forest species and densities
of Limax cinereoniger. The latter species seems to need forests of >1,000 ha, i.e., well above the size of most fragments. In conclusion, the prediction
is valid only for forest species. The response to fragmentation is species specific and seems to depend on habitat specialization
and macroclimatic conditions.
Jean-Pierre Maelfait: Deceased. 相似文献
18.
Forests within and adjacent to cities are important habitats for native species and provide vital ecosystem services to cities and their residents. Herbaceous plants represent over 80% of all plant species in these forests, yet little is known about the long-term effects of management and landscape context on the understory of suburban forests. In this study, we used a 30-year dataset to fill this knowledge gap and evaluate the effect of prescribed burns on native forest herbs in suburban forest preserves of DuPage County, Illinois, USA. We also evaluated how the amount and configuration of forest habitat at multiple spatial scales affects native herb richness, gains, and losses in these forests over 30 years. We found that forests managed with prescribed burns increased in native herb richness over time, while unburned forests did not. Managed forests now have more native herb species than unburned forests. We also found that habitat amount in the surrounding landscape, but not the configuration of that habitat, had a positive effect on native herb richness and species gains over 30 years. Overall, we conclude that prescribed burns are effective in maintaining native forest herb richness in suburban forests. However, additional management actions such as seed augmentation may be required in areas with little surrounding forest herb habitat, as both overall richness and species gains over time are reduced in isolated forests. 相似文献
19.
Judith A. Simon Joel W. Snodgrass Ryan E. Casey Donald W. Sparling 《Landscape Ecology》2009,24(3):361-373
Many amphibian species rely on both aquatic and terrestrial habitats to complete their life cycles. Therefore, processes operating
both within the aquatic breeding habitat, and in the surrounding uplands may influence species distributions and community
composition. Moreover, changes in land use adjacent to breeding site may degrade aquatic habitats. To assess land use effects
on pond-breeding amphibian assemblages, we investigated relationships between land use, breeding habitat conditions, and breeding
amphibian use of constructed wetlands in urban environments of the Baltimore metropolitan area, USA. Forest and impervious
surface associations with species richness and occurrence occurred at spatial scales ranging from 50 to 1,000 m, with strongest
relationships at 500 m. Forest and impervious surface cover within 1,000 m of ponds were also related to water and sediment
quality, which in turn were capable of explaining a proportion of the observed variation in species richness and occurrence.
Taken together, our results suggest that forest and other land covers within relatively proximal distances to ponds (i.e.,
within 50–1,000 m) may be influencing species richness directly via the provisioning of upland habitat, and indirectly via
influences on within pond habitat quality.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
Traditional agricultural mosaic landscapes are likely to undergo dramatic changes through either intensification or abandonment
of land use. Both developmental trends may negatively affect the vascular plant species richness of such landscapes. Therefore,
sustainable land-use systems need to be developed to maintain and re-establish species richness at various spatial scales.
To evaluate the sustainability of specific land-use systems, we need approaches for the effective assessment of the present
species richness and models that can predict the effects on species richness as realistically as possible. In this context,
we present a methodology to estimate and predict vascular plant species richness at the local and the regional scale. In our
approach, the major determinants of vascular plant species richness within the study area are taken into consideration: These
are according to Duelli's mosaic concept the number of habitat types and of habitat patches within area units. Furthermore,
it is based on the relative frequencies of species within habitat types. Our approach comprises six steps: (i) the determination
of present habitat patterns within an observation area, (ii) the creation of a land-use scenario with simulated habitat patterns,
(iii) the determination of species frequencies within habitat types of this area, (iv) a grouping of habitat-specific species,
(v) the estimation of the probabilities for all species (or habitat specialists) to occur, either in stepwise, exponentially
enlarged landscape tracts (local scale), or in the entire observation area (regional scale), and (vi) the validation of the
estimated species numbers. The approach will be exemplified using data from the municipal district of Erda, Lahn-Dill Highlands,
Germany. The current species numbers to be expected on the basis of probability calculations were compared with those recorded
on the basis of extensive field work. This comparison shows that, on the basis of our simple calculations, the current local
plant species richness can be predicted well, with a slight underestimation.
This revised version was published online in May 2005 with corrections to the Cover Date.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献