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1.
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
2.
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
3.
Understanding the determinants of hedgerow plant diversity in agricultural landscapes remains a difficult task, because the
potential drivers affect the complete range of biodiversity components (alpha to gamma diversity). We surveyed herbaceous
plant communities (of a height <1.5 m) in 84 hedgerows in the Seine river floodplain of France. Two types of potential drivers
for species richness, accounting for landscape mosaic and hedgerow network, were recorded at both hedgerow and site scale.
The distribution of species richness through the components of alpha hedgerow diversity (i.e. the average diversity within
a habitat) and gamma hedgerow diversity (i.e. the total diversity across habitats) were assessed using additive partitioning
methods, while the relationship between species diversity and its potential landscape drivers at both scales was modeled using
Generalized Additive Models. Our results indicated that gamma hedgerow diversity is explained by the heterogeneity of the
landscape structure, which is correlated with the mosaic of agricultural land use. At this scale, intrinsic properties of
the configuration of the hedgerow networks have a weak influence on species richness. Alpha hedgerow diversity is also explained
by landscape variables, accounting for both the configuration of agricultural mosaics and hedgerow networks, but to a lesser
extent. Time lags for species responses are shown at both scales, and for the two types of drivers. Extinction or colonization
debt may be indicated at both scales, while the remnant effects of former practices may also be responsible for such patterns
at a local scale. We suggest that hedgerow management should take the specific parameters of both scales into account. At
a local scale, management actions should aim to decrease the influence of adjacent land use when the impact is negative, through
the implementation of extended buffer zones, while at the landscape and farm scales, agri-environmental schemes should be
dedicated to the conservation of specific agricultural land uses. 相似文献
4.
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
5.
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
6.
Michael C. Wimberly 《Landscape Ecology》2006,21(1):35-46
Although landscape ecology emphasizes the effects of spatial pattern on ecological processes, most neutral models of species–habitat relationships have treated habitat as a static constraint. Do the working hypotheses derived from these models extend to real landscapes where disturbances create a shifting mosaic? A spatial landscape simulator incorporating vegetation dynamics and a metapopulation model was used to compare species in static and dynamic landscapes with identical habitat amounts and spatial patterns. The main drivers of vegetation dynamics were stand-replacing disturbances, followed by gradual change from early-successional to old-growth habitats. Species dynamics were based on a simple occupancy model, with dispersal simulated as a random walk. As the proportion of available habitat (p) decreased from 1.0, species occupancy generally declined more rapidly and reached extinction at higher habitat levels in dynamic than in static landscapes. However, habitat occupancy was sometimes actually higher in dynamic landscapes than in static landscapes with similar habitat amounts and patterns. This effect was most pronounced at intermediate amounts of habitat (p = 0.3?0.6) for mobile species that had high colonization rates, but were unable to cross non-habitat patches. Differences between static and dynamic landscapes were contingent upon the initial metapopulation size and the shapes of disturbances and the resulting habitat patterns. Overall, the results demonstrate that dispersal-limited species exhibit more pronounced critical behavior in dynamic landscapes than is predicted by simple neutral models based on static landscapes. Thus, caution should be exercised in extending generalizations derived from static landscape models to disturbance-driven landscape mosaics. 相似文献
7.
Pablo González-Moreno Joan Pino David Carreras Corina Basnou Iván Fernández-Rebollar Montserrat Vilà 《Landscape Ecology》2013,28(5):891-903
Landscape pattern might be an important determinant of non-native plant invasions because it encompasses components influencing the availability of non-native plant propagules and disturbance regimes. We aimed at exploring the relative role of patch and landscape characteristics, compared to those of habitat type and regional human influence on non-native plant species richness. For this purpose, we identified all non-native plant species in 295 patches of four coastal habitat types across three administrative regions in NE Spain differing in the degree of human influence. For each patch, we calculated several variables reflecting habitat patch geometry (size and shape), landscape composition (distribution of land-cover categories) and landscape configuration (arrangement of patches). The last two groups of variables were calculated at five different spatial extents. Landscape composition was by far the most important group of variables associated with non-native species richness. Natural areas close to diverse and urban landscapes had a high number of non-native species while surrounding agricultural areas could buffer this effect. Regional human influence was also strongly associated with non-native species richness while habitat type was the least important factor. Differences in sensitivity of landscape variables across spatial extents proved relevant, with 100 m being the most influential extent for most variables. These results suggest that landscape characteristics should be considered for performing explicit spatial risk analyses of plant invasions. Consequently, the management of invaded habitats should focus not only at the stand scale but also at the highly influential neighbouring landscape. Prior to incorporate landscape characteristics into management decisions, sensitivity analyses should be taken into account to avoid inconsistent variables. 相似文献
8.
Habitat loss and fragmentation of natural and semi-natural habitats are considered as major threats to plant species richness.
Recently several studies have pinpointed the need to analyse past landscape patterns to understand effects of fragmentation,
as the response to landscape change may be slow in many organisms, plants in particular. We compared species richness in continuously
grazed and abandoned grasslands in different commonplace rural landscapes in Sweden, and analysed effects of isolation and
area in three time-steps (100 and 50 years ago and today). Old cadastral maps and aerial photographs were used to analyse
past and present landscape patterns in 25 sites. Two plant diversity measures were investigated; total species richness and
species density. During the last 100 years grassland area and connectivity have been reduced by about 90%. Present-day habitat
area was positively related to total species richness in both habitats. There was also a relationship to habitat area 50 years
ago for continuously grazed grasslands. Only present management was related to species density: continuously grazed grasslands
had the highest species density. There were no relationships between grassland connectivity, present or past, and any diversity
measure. We conclude that landscape history is not directly important for present-day plant diversity patterns in ordinary
landscapes, although past grassland management is a prerequisite for the grassland habitats that can be found there today.
It is important that studies are conducted, not only in very diverse landscapes, but also in managed landscapes in order to
assess the effects of fragmentation on species. 相似文献
9.
This paper presents a method for characterizing the complexity of landscape boundaries by remote sensing. This characterization is supported by a new boundary typology, that takes into account points where three or more landcovers converge (i.e., convergency points or coverts). Landscape boundary richness and diversity indices were proposed and calculated over 19 landscapes in South-East Brazil. Results showed that landscape boundaries, especially convergency points, provided an enrichment in landscape pattern analysis. Landcover boundary diversities were significantly related to landcover shape: elongated riparian units had the highest values for boundary diversity and coverts proportion indices. On the other hand, landscape analysis showed that indices of shape, richness, diversity and coverts proportion provided an additional evaluation of landcover spatial distribution within the landscape. 相似文献
10.
The factors responsible for widespread declines of grassland birds in the United States are not well understood. This study,
conducted in the short-grass prairie of eastern Wyoming, was designed to investigate the relationship between variation in
habitat amount, landscape heterogeneity, prey resources, and spatial variation in grassland bird species richness. We estimated
bird richness over a 5-year period (1994–1998) from 29 Breeding Bird Survey locations. Estimated bird richness was modeled
as a function of landscape structure surrounding survey routes using satellite-based imagery (1996) and grasshopper density
and richness, a potentially important prey of grassland birds. Model specification progressed from simple to complex explanations
for spatial variation in bird richness. An information-theoretic approach was used to rank and select candidate models. Our
best model included measurements of habitat amount, habitat arrangement, landscape matrix, and prey diversity. Grassland bird
richness was positively associated with grassland habitat; was negatively associated with habitat dispersion; positively associated
with edge habitats; negatively associated with landscape matrix attributes that may restrict movement of grassland bird; and
positively related to grasshopper richness. Collectively, 62% of the spatial variation in grassland bird richness was accounted
for by the model (adj-R2 = 0.514). These results suggest that the distribution of grassland bird species is influenced by a complex mixture of factors
that include habitat area affects, landscape pattern and composition, and the availability of prey. 相似文献
11.
Additive partitioning of plant species diversity in an agricultural mosaic landscape 总被引：14，自引：1，他引：13
In this paper, we quantify the effects of habitat variability and habitat heterogeneity based on the partitioning of landscape species diversity into additive components and link them to patch-specific diversity. The approach is illustrated with a case study from central Switzerland, where we recorded the presence of vascular plant species in a stratified random sample of 1'280 quadrats of 1 m2 within a total area of 0.23 km2. We derived components of within- and between-community diversity at four scale levels (quadrat, patch, habitat type, and landscape) for three diversity measures (species richness, Shannon index, and Simpson diversity). The model implies that what we measure as within-community diversity at a higher scale level is the combined effect of heterogeneity at various lower levels. The results suggest that the proportions of the individual diversity components depend on the habitat type and on the chosen diversity aspect. One habitat type may be more diverse than another at patch level, but less diverse at the level of habitat type. Landscape composition apparently is a key factor for explaining landscape species richness, but affects evenness only little. Before we can test the effect of landscape structure on landscape species richness, several problems will have to be solved. These include the incorporation of neighbourhood effects, the unbiased estimation of species richness components, and the quantification of the contribution of a landscape element to landscape species richness. 相似文献
12.
Elsa Aggemyr Alistair G. Auffret Love Jädergård Sara A. O. Cousins 《Landscape Ecology》2018,33(12):2273-2284
Context
Understanding how landscape patterns affect species diversity is of great importance in the fields of biogeography, landscape ecology and conservation planning, but despite the rapid advance in biodiversity analysis, investigations of spatial effects on biodiversity are still largely focused on species richness.Objectives
We wanted to know if and how species richness and species composition are differentially driven by the spatial measures dominating studies in landscape ecology and biogeography. As both measures require the same limited presence/absence information, it is important to choose an appropriate diversity measure, as differing results could have important consequences for interpreting ecological processes.Methods
We recorded plant occurrences on 112 islands in the Baltic archipelago. Species richness and composition were calculated for each island, and the explanatory power of island area and habitat heterogeneity, distance to mainland and structural connectivity at three different landscape sizes were examined.Results
A total of 354 different plant species were recorded. The influence of landscape variables differed depending on which diversity measure was used. Island area and structural connectivity determined plant species richness, while species composition revealed a more complex pattern, being influenced by island area, habitat heterogeneity and structural connectivity.Conclusions
Although both measures require the same basic input data, species composition can reveal more about the ecological processes affecting plant communities in fragmented landscapes than species richness alone. Therefore, we recommend that species community composition should be used as an additional standard measure of diversity for biogeography, landscape ecology and conservation planning.13.
Nicholas J. Berry Oliver L. Phillips Robert C. Ong Keith C. Hamer 《Landscape Ecology》2008,23(8):915-929
Selective logging of tropical forests imposes spatial pattern on the landscape by creating a mosaic of patches affected by
different intensities of disturbance. To understand the ecological impacts of selective logging it is therefore necessary
to explore how patterns of tree species composition are affected by this patchy disturbance. This study examines the impacts
of selective logging on species composition and spatial patterns of vegetation structure and tree diversity in Sabah, Borneo.
We compare tree diversity between logged and unlogged forest at three scales: species richness within plots, species turnover
among plots, and total species richness and composition of plots combined. Logging had no effect on tree diversity measured
at the smallest scale. Logged forest had a greater rate of species turnover with distance, so at a large spatial scale it
supported more tree species than the relatively homogeneous unlogged area. Tree species composition also differed significantly
between the two types of forest, with more small dipterocarps and large pioneers in logged forest, and more large dipterocarps
in unlogged forest. Our results emphasize the importance of sampling at a sufficiently large scale to represent patterns of
biodiversity within tropical forest landscapes. Large areas of production forest in SE Asia are threatened with conversion
to commercial crops; our findings show that selectively logged forest can retain considerable conservation value. 相似文献
14.
Landscape cohesion: an index for the conservation potential of landscapes for biodiversity 总被引：14，自引：6，他引：14
In urbanising landscapes, planning for sustainable biodiversity occurs in a context of multifunctional land use. Important
conditions for species persistence are habitat quality, the amount and configuration of habitat and the permeability of the
landscape matrix. For planning purposes, these determinants should be integrated into simple indicators for spatial conditions
of persistence probability. We propose a framework of three related indices. The cohesion index is based on the ecology of
metapopulations in a habitat network. We discuss how an indicator for species persistence in such a network could be developed.
To translate this network index into an area index, we propose the concept of spatial cohesion. Habitat cohesion and spatial
cohesion are defined and measured for single species or, at best, for species profiles. Since species differ in their perception
of the same landscape, different species will rate different values of these indices for the same landscape. Because landscapes
are rarely planned for single species, we further propose the index of landscape cohesion, which integrates the spatial cohesion
indices of different species. Indices based on these concepts can be built into GIS tools for landscape assessment. We illustrate
different applications of these indices, and emphasise the distinction between ecological and political decisions in developing
and applying such tools.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
Land cover change, predominantly habitat conversion to agricultural use and urbanization, has recently been recognized as
the primary cause of biodiversity loss in terrestrial ecosystems. We evaluated the relative effects of urban and agricultural
landscapes on anuran species richness and the abundance of six anuran species found at breeding ponds in and around the cities
of Ottawa, Ontario and Gatineau, Quebec. We performed six call surveys at 29 permanent focal ponds surrounded by one of three
landscape contexts: primarily urban, primarily agricultural, and primarily forested. We also measured three local pond variables
to control for the effects of local habitat quality in our analyses. We found that anuran species richness was significantly
lower in breeding ponds in urban landscapes compared to forested and agricultural landscapes, which exhibited no significant
difference in species richness. The abundances of individual anuran species were also consistently lower in urban landscapes
for all species except one, which exhibited no response to landscape type. Three species had their highest abundances in ponds
in forested landscapes, whereas two species had their highest abundances in ponds in agricultural landscapes. We conclude
that ponds embedded in urban landscapes support lower biodiversity than ponds in agricultural settings. We suggest that landscapes
composed of a mosaic of forest and open habitats surrounding wetlands would hold the highest biodiversity of these species. 相似文献
16.
Effects of area and isolation of woodland patches on herbaceous plant species richness across Great Britain 总被引：5，自引：2，他引：5
Petit Sandrine Griffiths Leila Smart Simon S. Smith Geoff M. Stuart Rick C. Wright Simon M. 《Landscape Ecology》2004,19(5):463-471
Richness of Ancient Woodland Indicator plant species was analysed in 308 woodland patches that were surveyed during the Countryside Survey of Great Britain carried out in 1998. The Countryside Survey recorded vegetation plots and landscape structure in 569 stratified 1 km sample squares and developed a remotely-sensed land cover map of the UK. Using these datasets, we tested the hypothesis that Ancient Woodland Indicator species richness in woodland fragments was limited by patch area, shape and spatial isolation and that woodland patches located in the lowland region of Great Britain would respond differently than those in the upland region. The variation in Ancient Woodland Indicator species richness in the British lowlands (n = 218) was mainly explained by patch area and two measures of connectivity, the length of hedgerows and lines of trees in the 1 km square and the area of woodland within 500 m of the vegetation plot. By contrast, variation in Ancient Woodland Indicator species richness in the British uplands (n = 90) was related to Ellenberg scores of the vegetation communities sampled – a surrogate for habitat quality – and no significant effect of spatial structure was detected. It therefore appears that the degree of fragmentation of woodland in the British lowlands limits the distribution of Ancient Woodland Indicator species, while in the uplands, failed colonisation is a matter of habitat quality rather than a result of landscape structure.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
17.
18.
Responses of Chilean forest birds to anthropogenic habitat fragmentation across spatial scales 总被引：1，自引：1，他引：0
Although it is recognized that anthropogenic forest fragmentation affects habitat use by organisms across multiple spatial
scales, there is uncertainty about these effects. We used a hierarchical sampling design spanning three spatial scales of
habitat variability (landscape > patch > within-patch) and generalized mixed-effect models to assess the scale-dependent responses
of bird species to fragmentation in temperate forests of southern Chile. The abundances of nine of 20 bird species were affected
by interactions across spatial scales. These interactions resulted in a limited effect of within-patch habitat structure on
the abundance of birds in landscapes with low forest cover, suggesting that suitable local habitats, such as sites with dense
understory cover or large trees, are underutilized or remain unused in highly fragmented landscapes. Habitat specialists and
cavity-nesters, such as tree-trunk foragers and tapaculos, were most likely to exhibit interactions across spatial scales.
Because providing additional sites with dense understory vegetation or large habitat trees does not compensate the negative
effect of the loss of forest area on bird species, conservation strategies should ensure the retention of native forest patches
in the mixed-use landscapes. 相似文献
19.
Assessing and predicting the species richness of a complex landscape remains a problem because there is no simple scaling function of species richness in a heterogeneous environment. Furthermore, the potential value of an area for biodiversity conservation may depend on which, rather than how many, species the area contains. This paper shows how we can objectively evaluate the contribution of an area, e.g., a habitat patch, to larger-scale plant species richness, e.g., a landscape composed of patches of several habitat types, and how we can test hypotheses that attempt to explain this contribution. We quantified the concept of habitat specificity to assess the proportion of each observed plant population that is concentrated within a given spatial element. A case study of a biodiversity-monitoring program in the Swiss Canton of Aargau showed that the relative contribution of the three main types of land use to the overall species richness differed strongly between higher taxa (vascular plants and molluscs). However, the type of data, i.e., presence-absence or abundance, was not important. Resampling of the plant data suggested that stratification provided an unbiased estimate of relative specificity, whereas unstratified sampling caused bias even for large samples. In a second case study of vascular plants in an agricultural landscape in central Switzerland, we tested whether the type, size or shape of a landscape element can predict its contribution to the species richness of the landscape. Habitat types that were less frequently disturbed contributed more per m2 to landscape species richness than more frequently disturbed ones. Contrary to expectation, patch size was negatively correlated to specificity per m2 for arable fields, whereas patch shape appeared to be unrelated to the specificity per m2 both for arable fields and for meadows. The specificity approach provides a solution to the problem of scaling species richness and is ideally suited for testing hypotheses on the effect of landscape structure on landscape species richness. Specificity scores can easily be combined with measures of other aspects of rarity to assess the contribution of a spatial element to conservation goals formulated at regional, national or global level. 相似文献
20.
Habitat fragmentation strongly affects insect species diversity and community composition, but few studies have examined landscape
effects on long term development of insect communities. As mobile consumers, insects should be sensitive to both local plant
community and landscape context. We tested this prediction using sweep-net transects to sample insect communities for 8 years
at an experimentally fragmented old-field site in northeastern Kansas, USA. The site included habitat patches undergoing secondary
succession, surrounded by a low turf matrix. During the first 5 years, plant richness and cover were measured in patches.
Insect species richness, total density, and trophic diversity increased over time on all transects. Cover of woody plants
and perennial forbs increased each year, adding structural complexity to successional patches and potentially contributing
to increased insect diversity. Within years, insect richness was significantly greater on transects through large successional
patches (5000 m2) than on transects through fragmented arrays of 6 medium-sized (total area 1728 m2) or 15 small (480 m2) patches. However, plant cover did not differ among patch types and was uncorrelated with insect richness within years. Insect
richness was strongly correlated with insect density, but trophic and α diversities did not differ among patch types, indicating
that patch insect communities were subsets of a common species pool. We argue that differences in insect richness resulted
from landscape effects on the size of these subsets, not patch succession rates. Greater insect richness on large patches
can be explained as a community-level consequence of population responses to resource concentration. 相似文献