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1.
The reliability of ants as bioindicators of ecosystem condition is dependent on the consistency of their response to localised
habitat characteristics, which may be modified by larger-scale effects of habitat fragmentation and loss. We assessed the
relative contribution of habitat fragmentation, habitat loss and within-patch habitat characteristics in determining ant assemblages
in semi-arid woodland in Queensland, Australia. Species and functional group abundance were recorded using pitfall traps across
20 woodland patches in landscapes that exhibited a range of fragmentation states. Of fragmentation measures, changes in patch
area and patch edge contrast exerted the greatest influence on species assemblages, after accounting for differences in habitat
loss. However, 35% of fragmentation effects on species were confounded by the effects of habitat characteristics and habitat
loss. Within-patch habitat characteristics explained more than twice the amount of species variation attributable to fragmentation
and four times the variation explained by habitat loss. The study indicates that within-patch habitat characteristics are
the predominant drivers of ant composition. We suggest that caution should be exercised in interpreting the independent effects
of habitat fragmentation and loss on ant assemblages without jointly considering localised habitat attributes and associated
joint effects.
The State of Queensland's right to retain a non-exclusive, royalty free license in and to any copyright is acknowledged. 相似文献
2.
Habitat edges can alter population dynamics, influence community structure, determine the success of conservation efforts,
and facilitate the spread of invasive species. Despite recognition that edges influence the nature and strength of ecological
interactions, edges are generally characterized using abiotic measures that likely capture habitat quality for only the focal
taxa, and ignore the potential for biotic interactions to explain edge effects. Here we describe the association between edges
and the density of an invasive shrub, Lonicera maackii, and infer the functional role of edges by using multiple criteria to weight edge contrast. We define edge contrast using
both an abiotic criterion in which contrast is weighted by differences in light availability, and a biotic criterion in which
edge contrast is weighted by the association between edges and the abundance of the American Robin (Turdus migratorius), an important avian seed disperser. Biotically defining edge contrast significantly improved model fit in all cases, demonstrating
that the large-scale distribution of an invasive shrub is best predicted using both abiotic and biotic edge characterization.
More generally, our work suggests that weighting edge contrast using key biological interactions in addition to abiotic criteria
may be a promising way to understand the multiple pathways by which edges influence the distribution and abundance of organisms. 相似文献
3.
Sarel S. Cilliers Nicholas S. G. Williams Francois J. Barnard 《Landscape Ecology》2008,23(10):1243-1256
Linear native grassland remnants in fragmented landscapes are usually at a great risk of exotic species invasion from their
edges. Changes in species distribution near habitat edges are extensively studied in ecology as knowledge about edge responses
is important to understand the development of patterns and processes in landscapes. However, elucidating robust general principles
for edge effects has been difficult as species responses to habitat edges are highly variable and dependent on a large number
of attributes which affect the function and structure of edges and therefore the distance that edge effects penetrate into
fragmented natural vegetation. The objective of this study was to investigate the generality of exotic species invasion patterns
from edges in native grassland patches surrounded by urban and rural landscapes. This was done by comparing the results of
research from Victoria, Australia with a similar study from North-West Province, South Africa. Despite their occurrence on
different continents, the grasslands are floristically and structurally similar and are dominated by the same grass species.
Invasion patterns were quantified using two spatial statistics methods; block kriging and spatially constrained clustering.
Two distinct patterns of exotic species invasion were identified in native grassland remnants in South Africa and Australia,
namely exotic species invasion from the edge where the cover of exotic species increased with increasing proximity to the
edge and a pattern that suggests that gap phase vegetation dynamics may also drive exotic species invasion at urban grasslands.
Although urbanization and weed invasions are complex processes similar patterns of exotic species invasion in urban grasslands
were found in two different continents suggesting that general patterns may occur. Implications of this for the conservation
of native grasslands in contrasting landscapes are discussed. 相似文献
4.
Forest loss has been invoked as a cause for changes in the reproductive success of animal-pollinated woodland plants, associated
with changes in their pollinators. To analyze such effects, it is important to include all of the three key players: landscapes,
pollinators and a plant. We investigated effects of forest loss on an insect-pollinated plant through landscapes in forested
ecosystems to pollinator communities and plant populations. Then we questioned if abundance and species richness in pollinator
communities decrease as forest loss increases, and this in turn leads to a decrease in reproductive output of an insect-pollinated
plant. We made a study with 12 populations of the bee pollinated herb, Erythronium americanum, in a landscape characterized by scattered fragments of deciduous forest within intensively managed agricultural fields.
We also sampled bees as the potential pollinators by pan traps. We quantified the study landscapes using the amount of forest
cover and the length of forest edge within each of the six radii (250, 500, 750, 1,000, 1,250 and 1,500 m). Regression analyses
showed that the abundance and species richness of all collected bees were positively related to only the forest cover at the
radius of 750 m. We also found the positive relationships for the seed set of E. americanum when the forest cover at the same radius and abundance of all collected bees were used as the predictor variables. These
results indicate that forest loss causes negative impacts on potential pollinator communities and seed sets of some woodland
herbs. 相似文献
5.
Habitat fragmentation is considered a major cause of biodiversity loss, both on terrestrial and marine environments. Understanding the effects of habitat fragmentation on the structure and dynamics of natural communities is extremely important to support management actions for biodiversity conservation. However, the effects of habitat fragmentation on marine communities are still poorly understood. Here we evaluated whether habitat fragmentation affects the structure of epifaunal communities in the sublittoral zone, in the northern coast of São Paulo state, Brazil. Five experimental landscapes were constructed, each one forming a large continuous patch. After 4 weeks, each landscape was cut on three patches of different sizes. Epifaunal macroinvertebrate communities were sampled at the edge and interior of experimental landscapes before manipulation to evaluate edge effects. After four more weeks, communities from the three patch sizes were also sampled to evaluate patch size effects. We compared the diversity of communities at different levels of fragmentation by total abundance, rarefied taxon richness, Shannon–Wiener diversity index, Simpson’s dominance index, and abundance of dominant taxa. Higher taxon richness and gastropod abundance were recorded in the patch edges, but no significant differences were found among patch sizes. We found a significant effect of habitat fragmentation, with lower abundances of Gammaridea (the dominant taxon), Ophyuroidea, and Pycnogonida after the experimental fragmentation. Lower abundances of dominant taxa resulted in higher diversity and lower dominance in fragmented landscapes when compared to integral, pre-manipulation landscapes. Our results suggest that fragmentation of landscapes in the system studied can reduce dominance, and that even small patch sizes can be important for the conservation of macroinvertebrate diversity. 相似文献
6.
Rippel Tyler M. Mooring Eric Q. Tomasula Jewel Wimp Gina M. 《Landscape Ecology》2020,35(10):2179-2190
Context
Habitat fragmentation is known to be one of the leading causes of species extinctions, however few studies have explored how habitat fragmentation impacts ecosystem functioning and carbon cycling, especially in wetland ecosystems.
ObjectivesWe aimed to determine how habitat fragmentation, defined by habitat area and distance from habitat edge, impacts the above-ground carbon cycling and nutrient stoichiometry of a foundation species in a coastal salt marsh.
MethodsWe conducted our research in a salt marsh in the Mid-Atlantic United States, where the foundation grass species Spartina patens is being replaced by a more flood-tolerant grass, leading to highly fragmented habitat patches. We quantified decomposition rates, live biomass, and litter accumulation of S. patens at patch edges and interiors. Additionally, we measured relevant characteristics (e.g., habitat area, elevation, microclimate) of S. patens patches.
ResultsHabitat edge effects, and not habitat area effects, had distinct impacts on ecosystem functioning. Habitat edges had less litter accumulation, faster decomposition rates, a warmer and drier microclimate, and lower elevations than patch interiors. Patches with low elevation edges had the fastest decomposition rates, while interiors of patches at any elevation had the slowest decomposition rates. Notably, these impacts were not driven by changes in primary production.
ConclusionHabitat fragmentation impacts the above-ground carbon cycling of S. patens in coastal wetlands by altering litter decomposition, but not primary production, through habitat edge effects. Future research should investigate whether this pattern scales across broader landscapes and if it is observable in other wetland ecosystems.
相似文献7.
Land-bridge islands formed by dam construction are considered to be “experimental” systems for studying the effects of habitat
loss and fragmentation, offering many distinct advantages over terrestrial fragments. The Thousand Island Lake in Southeast
China is one such land-bridge system with more than 1000 islands. Based on a field survey of vascular plant richness on 154
land-bridge islands during 2007–2008, we examined the effects of island and landscape attributes on plant species richness
and patterns of species nestedness. We also examined the different responses of plant functional groups (classified according
to growth form and shade tolerance) to fragmentation. We found that island area explained the greatest amount of variation
in plant species richness. Island area and shape index positively affected species diversity and the degree of nestedness
exhibited by plant communities while the perimeter to area ratio of the islands had a negative effect. Shade-tolerant plants
were the most sensitive species group to habitat fragmentation. Isolation negatively affected the degree of nestedness in
herb and shade-intolerant plants including species with various dispersal abilities in the fragmented landscape. Based on
these results, we concluded that the effects of habitat loss and fragmentation on overall species richness depended mostly
on the degree of habitat loss, but patterns of nestedness were generated from different ecological mechanisms due to species-specific
responses to different characteristics of habitat patches. 相似文献
8.
Edge and area effects on avian assemblages and insectivory in fragmented native forests 总被引：1，自引：1，他引：0
Luc Barbaro Eckehard G. Brockerhoff Brice Giffard Inge van Halder 《Landscape Ecology》2012,27(10):1451-1463
Disentangling the confounded effects of edge and area in fragmented landscapes is a recurrent challenge for landscape ecologists, requiring the use of appropriate study designs. Here, we examined the effects of forest fragment area and plot location at forest edges versus interiors on native and exotic bird assemblages on Banks Peninsula (South Island, New Zealand). We also experimentally measured with plasticine models how forest fragment area and edge versus interior location influenced the intensity of avian insectivory. Bird assemblages were sampled by conducting 15?min point-counts at paired edge and interior plots in 13 forest fragments of increasing size (0.5?C141?ha). Avian insectivory was measured as the rate of insectivorous bird attacks on plasticine models mimicking larvae of a native polyphagous moth. We found significant effects of edge, but not of forest patch area, on species richness, abundance and composition of bird assemblages. Exotic birds were more abundant at forest edges, while neither edge nor area effects were noticeable for native bird richness and abundance. Model predation rates increased with forest fragmentation, both because of higher insectivory in smaller forest patches and at forest edges. Avian predation significantly increased with insectivorous bird richness and foraging bird abundance. We suggest that the coexistence of native and exotic birds in New Zealand mosaic landscapes enhances functional diversity and trait complementation within predatory bird assemblages. This coexistence results in increased avian insectivory in small forest fragments through additive edge and area effects. 相似文献
9.
This study investigated the efficacy of linear landscape elements in fragmented landscapes as corridors for perennial grassland
species with short-range seed dispersal. Corridors are assumed to be essential for the persistence of metapopulations in fragmented
landscapes, but it is unclear to what extent linear landscape elements such as ditch banks and road verges can function as
corridors for those species. The principal factors that determine the rate of migration through corridors include the width
and habitat quality of patches within a corridor (expressed as the population growth rate λ) and the dispersal capacity of
plants (expressed as the slope α of the relationship between seed number and log-distance).
A cellular automation model was used to simulate the effects of the principal factors on the rate of migration. Simulations
with different levels of the principal factors showed highly significant and positive main effects of dispersal capacity,
habitat quality and width of corridors on the migration rate. Significant interactions existed between dispersal capacity
× width and dispersal capacity × habitat quality (p<0.0001), indicating that the effects of width and habitat quality depended
on the dispersal capacity. In narrow corridors most of the dispersed seeds were deposited outside the corridor, which significantly
reduced migration rates, especially for species with long-range dispersal (α=−0.4). In wide corridors (up to 20 m), seed losses
were much smaller and migration rates approximated those of continuous habitats. The contribution of the few long-range seeds
to the rate of migration was significant when habitat quality was high (population growth rates up to 2.5). However, in all
simulations migration rates were very low,i.e.<5 m/yr.
It is concluded that linear landscape elements are not effective corridors in fragmented landscapes for plants with short-range
seed dispersal, because migration rates are low (<5 m/yr), landscape elements vary in the percentage of high quality patches,
and refugia and suitable habitat patches are frequently several kilometres apart, making a cohesive infrastructure of corridors
for plants elusive. It is argued that the best way to conserve endangered plant species that encounter dispersal barriers
is to harvest seeds from nearby source populations and introduce them as suitable habitats. 相似文献
10.
We studied the effects of anthropogenic edges on predation and parasitism of forest bird nests in an agriculturally fragmented
landscape and a continuously forested landscape in Ontario, Canada. Nesting data were collected at 1937 nests across 10 species
in the fragmented landscape from 2002–2008, and 464 nests across 4 species in the continuously forested landscape from 2006–2008.
Brood parasitism only occurred in the fragmented landscape, and was positively related to the proportion of rural grassland
and row crop habitats within 500-m of nests. Daily nest survival was negatively related to the density of roads within 500-m
of nests in the fragmented landscape, but was not influenced by distance to anthropogenic edge in either landscape. Predation
rates were higher in the fragmented landscape for Ovenbird and Rose-breasted Grosbeak nests, but did not differ between landscapes
for Veery and American Redstart nests. Uniformly high predation in the fragmented landscape may be a result of (1) matrix
predators that penetrate deep (>300 m) into the forest interior, or (2) the additive effect of forest-dependent and matrix-associated
predators that results in high predation pressure in both edge and interior habitats. Further research focused on the identification
of nest predators, their population dynamics, and habitat use is required to understand the underlying mechanisms leading
to uniformly high nest predation in fragmented landscapes. 相似文献
11.
Effects of habitat edge may influence habitat quality, but landscape-scale implications of edge effects have rarely been quantified.
Sprague’s pipit (Anthus spragueii), a grassland obligate songbird, is declining rapidly throughout its range. Although habitat loss is implicated in the decline,
the causes are not well understood. We conducted 290 point counts across a 120 × 130 km study area in southern Alberta, Canada,
between 2000 and 2002, and used nonlinear regression to determine effects of distance to water, roads, and cropland or forage
habitats on relative abundance of Sprague’s pipits. We then used a geographic information system (GIS) to determine the effect
of edges on habitat suitability as indexed by relative abundance. Sprague’s pipit relative abundances declined by 25% from
the maximum predicted relative abundance within 900 m (CI = 660–1,280) of croplands or forage crops, and 340 m (CI = 280–460)
of wetlands, but there was no effect of roads. Fewer than 1% of grassland patches in the study area contained any habitat
far enough away from edge that they would be predicted to support at least 75% of the relative abundance of pipits expected
in the absence of edge effects. Only 33% of the landscape can support 75% or more of the relative abundance expected in the
absence of edge effects, as a result of habitat conversion or edge effects. Sprague’s pipit populations may be declining in
part because edge effects greatly magnify effects of habitat loss. 相似文献
12.
Context
The prevalence of edges is increasing due to anthropogenic landscape change. Edge responses can vary considerably between and within species. Understanding species’ responses to edges, and the causes of variation in such responses is central to managing biodiversity in contemporary landscapes.Objective
A resource distribution model predicts that species that require complementary resources in different land cover types will be most abundant at edges, displaying a positive edge response. Eastern tiger (Papilio glaucus) and spicebush (P. troilus) swallowtail butterflies use forest plant species for oviposition sites but open-habitat plants for nectar. They are excellent models for testing the positive edge response and exploring sources of variability in edge responses, such as species-specific traits or temporal effects.Methods
In southwestern Ontario, we examined both the abundance and flight orientation of these species in relation to forest/meadow edges and at different times of day. We used a transect method similar to the Pollard walk and a catch and release method, respectively.Results
The distribution and flight behaviour of these butterfly species were overall consistent with a positive edge response. Both species were most abundant at the edge and oriented their flight towards the edge from the forest and meadow. However, P. glaucus demonstrated a much stronger positive edge response, while P. troilus showed temporal variation in its response.Conclusions
Our results confirm the ability of the resource distribution model to predict species edge responses and movement behaviours, but also indicate that species-specific traits and time of sampling can influence such responses.13.
Context
Increased edge density is among the main negative effects of habitat loss and fragmentation. Roads are linear infrastructures that may promote barrier effects due to disturbance and mortality effects. We hypothesized that edges of habitat patches bordered by roads are less permeable than roadless edges.Objectives
We tested whether edge permeability and avoidance are influenced by the presence of paved and dirt roads bordering habitat patches, relatively to roadless edges.Methods
We translocated 55 montane akodonts (Akodon montensis) from the interior of vegetation remnants to their edges, and tracked fine-scale movements using spool-and-line devices. Edges were bordered by dirt roads (n = 12 mice), paved roads (n = 21) or were not bordered by roads (n = 22). We assessed edge permeability by comparing the number of tracks with crossings, and by comparing the empirical data to simulated correlated random walks. We also assessed edge avoidance by comparing the net direction travelled and net displacement from edge.Results
No edge crossings were recorded in roaded edges, whereas 36% of tracks in roadless edges crossed the edge at least once. Simulations indicated a significantly lower permeability of roaded edges, while the observed number of crossings in roadless edges was within the expected range. We found no evidence of higher avoidance of roaded edges, as both net direction travelled and displacement were similar across edge types.Conclusions
Roads decreased edge permeability for the montane akodont. This is likely to increase population isolation among vegetation remnants by reducing the structural connectivity in the already fragmented landscape.14.
Context
The study of habitat fragmentation is complex because multiple, potentially synergistic, ecological processes may be acting simultaneously. Further, edge effects themselves may be complex in that additivity from multiple edges can give rise to heterogeneous nearest–edge gradients.Objectives
We used heat diffusion as a proxy for additive edge effects in two study landscapes in order to test whether two key observations recently attributed to synergy between edge and area effects could be more simply explained by additivity; namely, steeper edge gradients in larger fragments and variation in slopes of species–area relationships as a function of distances to fragment edges.Methods
We sampled forest structure in northwestern Madagascar at various distances from the edge in fragments and continuous forest and used an inverse modelling approach to parameterize the model. In addition, we applied the model to data from a published study of beetle communities in fragmented forests in New Zealand.Results
With increasing proximity to edges, woody stem densities decreased and, as predicted, smaller fragments had lower stem densities and less steep edge gradients than larger ones. The model successfully predicted shifts in species–area relationships as a function of nearest–edge distances for beetle species, although observed richness for forest specialists in the smallest fragments was lower than predicted.Conclusions
Two key observations attributed to synergy between edge and area effects were explained by edge additivity. The model is particularly useful in that it can help to disentangle the complex sets of processes acting in fragmented landscapes.15.
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
16.
For early-successional species, road and powerline cuts through forests provide refugia and source populations for invading adjacent forest gaps. Within an 800 km2 forest matrix in South Carolina, we determined if width, disturbance frequency or linear features of road and powerline cuts influenced the mound distribution of the red imported fire ant, Solenopsis invicta Buren. For each of five linear habitat types, differing in width and disturbance frequency, we mapped all mounds located within ten 500 m segments. Mean mound density was lowest in narrow, infrequently-disturbed closed-canopy dirt road habitats (8.8 mounds/ha). For types with an opening in the forest canopy (i.e., open dirt road, gravel road, paved road and powerline cut), mean mound density was highest in narrow habitats where disturbance was intermediate (open dirt roads, 86.5 mounds/ha). It was lowest in wide habitats where disturbance was infrequent (powerline cuts, 27.6 mounds/ha). Mean mound size was greater in infrequently-disturbed powerline cuts than in frequently-disturbed paved roads. Mounds were located significantly closer to road or forest edges than expected by random. In all types except dirt roads, mounds were more common toward northern edges, and more so as the orientation of the linear habitat changed from north/south to east/west. These data suggest that narrow, disturbed habitats are more suitable for fire ant establishment and success than wider ones, and that the distribution of fire ants in linear habitats is not as uniform as it has been shown to be in pastures. A decrease in roadside disturbance and an increase in shade, especially along the northern edge, may result in lower fire ant mound density in these linear habitats. 相似文献
17.
Spiders associated with the meadow and tree canopies of orchards respond differently to habitat fragmentation 总被引：1，自引：0，他引：1
John D. Herrmann Debra Bailey Gabriela Hofer Felix Herzog Martin H. Schmidt-Entling 《Landscape Ecology》2010,25(9):1375-1384
The response of animal communities to habitat quality and fragmentation may vary depending on microhabitat associations of
species. For example, sensitivity of species to woody habitat fragmentation should increase with their degree of association
with woody plants. We investigated effects of local and landscape factors on spider communities in different microhabitats
within Swiss apple orchards. We expected a stronger negative effect of woody habitat fragmentation on spiders inhabiting tree
canopies compared to spiders living in the meadow. The 30 orchards that we sampled varied in woody habitat amount and isolation
at landscape and patch scales. Local factors included management intensity and plant diversity. Spiders associated with meadow
were affected by plant diversity, but not by fragmentation. In contrast, spiders associated with canopies responded to isolation
from other woody habitats. Surprisingly, we found both positive and negative effects of habitat isolation on local abundance.
This indicates that differences in dispersal and/or biotic interactions shape the specific response to habitat isolation.
The relative importance of local and landscape factors was in accordance with the microhabitat of the spiders. Thus, considering
microhabitat associations can be important for identifying processes that would be overlooked if sampling were pooled for
the whole habitat. 相似文献
18.
Edge geometry influences patch-level habitat use by an edge specialist in south-eastern Australia 总被引：1，自引：1，他引：0
We investigated patterns in habitat use by the noisy miner (Manorina melanocephala) along farmland-woodland edges of large patches of remnant vegetation (>300 ha) in the highly fragmented box-ironbark woodlands
and forests of central Victoria, Australia. Noisy miners exclude small birds from their territories, and are considered a
significant threat to woodland bird communities in the study region. Seventeen different characteristics of edge habitat were
recorded, together with the detection or non-detection of noisy miners along 129 500-m segments of patch edge. Habitat characteristics
ranged from patch-level factors related to patch-edge geometry to site-level floristic factors. Backward (stepwise) logistic
regression analyses were used to identify habitat characteristics that were associated with the occupancy of a site by noisy
miners. After accounting for the effects of spatial autocorrelation on the occurrence of noisy miners along edges, we identified
projections of remnant vegetation from the patch edge into the agricultural matrix (e.g., corners of patches, peninsulas of
vegetation) and clumps of trees in the agricultural matrix within 100 m of the edge as significant predictors of the occupancy
of edges by noisy miners. This relationship was also confirmed in two other geographically and floristically distinct habitats
within Victoria. The use of edges with projections by noisy miners may confer advantages in interspecific territorial defence.
In light of these results, we advocate revegetation strategies that attempt to enclose projections within 100 m of the edge,
with fencing placed out to this new boundary, to reduce the likelihood of colonisation and domination of an edge by noisy
miners. Our study highlights the need for greater consideration to be given to the patterns in habitat use by aggressive edge
specialists, particularly in relation to patch-edge geometry and other human-induced components of landscapes. 相似文献
19.
Context
Habitat edges are integral features of conservation corridors and can influence corridor function and effectiveness. Edge orientation is linked to corridor design and can shape edge responses by changing habitat conditions along edges as well as contrast between conserved habitats and transformed areas.
ObjectivesWe assess whether corridor orientation affects butterfly assemblages in conservation corridors. To do this, we investigate how edge orientation influences butterfly diversity and abundance along forestry plantation edges, and compare this to another important design variable, corridor width.
MethodsButterflies were recorded along the sunny austral north- and shady austral south-orientated edges in grassland conservation corridors that dissect forestry plantations, as well as corridor interior sites. Species richness, abundance and similarity to interior sites were modelled using local habitat variables (ambient temperature, floral resources, and time of day), as well as corridor design variables (corridor width, orientation and an estimate of edge contrast influenced by orientation).
ResultsBoth edge orientation and corridor width were important for butterfly diversity along corridor edges. Wider corridors enhanced overall species richness and promoted similarity between edge and interior habitats. Concurrently, grassland specialist species preferred the sunnier edges (i.e., north facing in the southern hemisphere) while forest- specialists showed a preference for the shadier edges (south facing edges). Edge orientation influenced resident butterflies more strongly than transient butterflies and influenced specialists more strongly than generalists.
ConclusionsCorridor orientation and width are complementary design variables for butterfly conservation. Wide corridors at a variety of orientations benefit different subsets of the butterfly assemblage, and the whole corridor (including both edges) is important to consider in conservation planning to capture all biodiversity.
相似文献20.
Simon J. Watson David M. Watson Gary W. Luck Peter G. Spooner 《Landscape Ecology》2014,29(7):1249-1259
The extent and connectivity of individual habitat types strongly affects the distribution and abundance of organisms. However, little is known of how the level of connectivity and the interactions between different habitat types influences the distribution of species. Here, we used the geographically restricted and endangered regent parrot Polytelis anthopeplus monarchoides as a case study to examine the importance of composition and connectivity between different elements in 39 complex landscape mosaics (each 10 km radius). We compiled a database of 674 regent parrot nesting records, regional vegetation maps and measures of multipath connectivity between core vegetation types under different scenarios of resistance to movement provided by landscape elements. The occurrence of regent parrot nests was strongly affected by landscape composition, being positively related to the extent Eucalyptus camaldulensis riverine forest, but negatively related to the extent of semi-arid woodlands dominated by Eucalyptus largiflorens. Connectivity between E. camaldulensis forest (principal nesting habitat) and mallee (preferred feeding habitat) was a strong predictor of nest locations. Our study shows that the suitability of fragmented agricultural landscapes for supporting species can be greatly affected by connectivity and interactions between preferred and non-preferred habitats. For species that require complementary habitats such as the regent parrot, conservation management activities may be ineffective if they simply focus on a single core habitat type or the impacts of human land uses without regard to the interrelationships among landscape elements. While increasing the amount of primary preferred habitat should remain a cornerstone goal, increasing the extent and improving connectivity with alternative landscape elements also should be priority management objectives. 相似文献