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1.
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
2.
Tradable biodiversity credit systems provide flexible means to resolve conflicts between development and conservation land-use
options for habitats occupied by threatened or endangered species. We describe an approach to incorporate the influence of
habitat fragmentation into the conservation value of tradable credits. Habitat fragmentation decreases gene flow, increases
rates of genetic drift and inbreeding, and increases probabilities of patch extinction. Importantly, tradable credit systems
will change the level of fragmentation over time for small and/or declining populations. We apply landscape equivalency analysis
(LEA), a generalizable, landscape-scale accounting system that assigns conservation value to habitat patches based on patch
contributions to abundance and genetic variance at landscape scales. By evaluating habitat trades using two models that vary
the relationship between dispersal behaviors and landscape patterns, we show that LEA provides a novel method for limiting
access to habitat at the landscape-scale, recognizing that the appropriate amount of migration needed to supplement patch
recruitment and to offset drift and inbreeding will vary as landscape pattern changes over time. We also found that decisions
based on probabilities of persistence alone would ignore changes in migration, genetic drift, and patch extinction that result
from habitat trades. The general principle of LEA is that habitat patches traded should make at least equivalent contributions
to rates of recruitment and migration estimated at a landscape scale. Traditional approaches for assessing the “take” and
“jeopardy” standards under the Endangered Species Act based on changes in abundance and probability of persistence may be
inadequate to prevent trades that increase fragmentation. 相似文献
3.
Ngcobo Samukelisiwe P. Ehlers Smith David A. Gumede S. Thobeka Sosibo Mbalenhle Ehlers Smith Yvette C. Downs Colleen T. 《Landscape Ecology》2022,37(7):1885-1903
Landscape Ecology - Forest loss and fragmentation are major drivers of biodiversity decline globally. However, with the widely recognised notion that biodiversity is multifaceted, few studies have... 相似文献
4.
Ownership and soil quality as sources of agricultural land fragmentation in highly fragmented ownership patterns 总被引:1,自引:0,他引:1
The relation between landscape structure and its drivers is a central issue in studies of landscape ecology. However, agricultural
land fragmentation is dealt with in only a few such studies. We have investigated the effects of ownership and soil quality
on agricultural land fragmentation in the highly fragmented ownership patterns that characterize some of the transition countries
of Central and Eastern Europe. Using patch-scale spatial data generated from GIS, Minimal Adequate Models, based on ANOVA,
were performed to test for the effects of ownership and soil quality patterns on arable land and grassland fragmentation across
483 study areas. The results show that there are important differences in the predictors of fragmentation between arable land
and grassland. Grassland fragmentation was found to be associated particularly with ownership fragmentation, whereas arable
land fragmentation tended to be driven mainly by soil conditions. A higher proportion of public ownership supports the more
frequent appearance of larger patches. We found a significantly positive relationship between natural soil fertility and arable
land fragmentation, while there was a strongly negative relationship between natural soil fertility and grassland fragmentation.
Soil quality diversity was observed to be the most important driver affecting arable land fragmentation, but only a non-significant
driver of grassland fragmentation. The study provides arguments for intervention aimed at reducing the huge differences between
the levels of land-ownership and the land-use fragmentation. 相似文献
5.
Naaf Tobias Feigs Jannis Till Huang Siyu Brunet Jörg Cousins Sara A. O. Decocq Guillaume De Frenne Pieter Diekmann Martin Govaert Sanne Hedwall Per-Ola Helsen Kenny Lenoir Jonathan Liira Jaan Meeussen Camille Plue Jan Poli Pedro Spicher Fabien Vangansbeke Pieter Vanneste Thomas Verheyen Kris Holzhauer Stephanie I. J. Kramp Katja 《Landscape Ecology》2021,36(10):2831-2848
Landscape Ecology - Evidence for effects of habitat loss and fragmentation on the viability of temperate forest herb populations in agricultural landscapes is so far based on population genetic... 相似文献
6.
Habitat amount and fragmentation usually covary in natural and simulated landscapes. A common way of distinguishing between
their effects is to take the residuals of the fragmentation index or indices regressed on habitat amount, as the index of
habitat fragmentation. We used data on prairie songbird relative abundances from southern Alberta, Canada to compare this
approach with the reverse: taking the residuals of habitat amount regressed on habitat fragmentation as the index of habitat
amount. We used generalized additive models (GAMs) to derive residuals, and modeled relative abundances using linear mixed-effects
models. The modeling approach used strongly influenced the statistical results. Using residuals as an index of fragmentation
resulted in an apparently stronger effect of habitat amount relative to habitat fragmentation. In contrast, habitat fragmentation
appeared more influential than habitat amount when residuals were used as an index of habitat amount. Regression of residuals
may eliminate statistical collinearity, but cannot distinguish between the ecological effects of habitat amount and fragmentation.
Habitat fragmentation may therefore have a larger effect on species than previously studies have shown, but experimental manipulations
of underlying mechanisms are ultimately required to address this debate. 相似文献
7.
Polyakov Maksym Rowles Alexei D. Radford James Q. Bennett Andrew F. Park Geoff Roberts Anna Pannell David 《Landscape Ecology》2013,28(2):329-341
Landscape Ecology - The removal, alteration and fragmentation of habitat are key causes of biodiversity decline worldwide. In Australia, temperate woodlands have been disproportionately cleared... 相似文献
8.
The effects of habitat area and fragmentation are confounded in many studies. Since a reduction in habitat area alone reduces
patch size and increases patch isolation, many studies reporting fragmentation effects may really be documenting habitat-area
effects. We designed an experimental landscape system in the field, founded on fractal neutral landscape models, to study
arthropod community responses to clover habitat in which we adjusted the level of fragmentation independently of habitat area.
Overall, habitat area had a greater and more consistent effect on morphospecies richness than fragmentation. Morphospecies
richness doubled between 10 and 80% habitat, with the greatest increase occurring up to 40% habitat. Fragmentation had a more
subtle and transient effect, exhibiting an interaction at intermediate levels of habitat only at the start of the study or
in the early-season (June) survey. In these early surveys, morphospecies richness was higher in clumped 40–50% landscapes
but higher in fragmented landscapes at 60–80% habitat. Rare or uncommon species are expected to be most sensitive to fragmentation
effects, and we found a significant interaction with fragmentation at intermediate levels of habitat for these types of morphospecies
in early surveys. Although the effects of fragmentation are expected to amplify at higher trophic levels, all trophic levels
exhibited a significant fragmentation effect at intermediate levels of habitat in these early surveys. Predators/parasitoids
were more sensitive to habitat area than herbivores, however. Thus, our results confirm that habitat area is more important
than fragmentation for predicting arthropod community responses, at least in this agricultural system. 相似文献
9.
Frauke Ecke Pernilla Christensen Per Sandström Birger Hörnfeldt 《Landscape Ecology》2006,21(4):485-497
Several studies indicate a long-term decline in numbers of different species of voles in northern Fennoscandia. In boreal Sweden, the long-term decline is most pronounced in the grey-sided vole (Clethrionomys rufocanus). Altered forest landscape structure has been suggested as a possible cause of the decline. However, habitat responses of grey-sided voles at the landscape scale have never been studied. We analyzed such responses of this species in lowland forests in Västerbotten, northern Sweden. Cumulated spring densities representing 22 local time series from 1980–1999 were obtained by a landscape sampling design and were related to the surrounding landscape structure of 2.5×2.5 km plots centred on each of the 22 1-ha trapping plots. In accordance with general knowledge on local habitat preferences of grey-sided voles, our study supported the importance of habitat variables such as boulder fields and old-growth pine forest at the landscape scale. Densities were negatively related to clear cuts. Habitat associations were primarily those of landscape structure related to habitat fragmentation, distance between habitat patches and patch interspersion rather than habitat patch type quantity. Local densities of the grey-sided vole were positively and exponentially correlated with spatial contiguity (measured with the fragmentation index) of old-growth pine forest, indicating critical forest fragmentation thresholds. Our results indicate that altered land use might be involved in the long-term decline of the grey-sided vole in managed forest areas of Fennoscandia. We propose two further approaches to reveal and test responses of this species to changes in landscape structure. 相似文献
10.
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
11.
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
12.
This study examines effects of different forest cutting patterns on habitat fragmentation in managed forest landscapes. We use computer simulation to conduct experiments in which we examine effects of different cutting patterns, cutting-unit size, and special constraints (e.g., a forest reserve, a stream system, or a road system) on landscape patterns. Fragmentation indices are used to quantify structural changes over the cutting cycle and among different treatments of the experiments. Degree of fragmentation varies greatly among the five cutting patterns used; aggregation of cutting units results in low degree and gradual change of fragmentation. Cutting patterns with larger cutting units and additional landscape constraints also lead to lower degree of fragmentation. Moreover, differences in fragmentation among the treatments are not observed until 30% or 50% of the landscape is cut. 相似文献
13.
Landscape division,splitting index,and effective mesh size: new measures of landscape fragmentation 总被引:37,自引:7,他引:37
Anthropogenic fragmentation of landscapes is known as a major reason for the loss of species in industrialized countries. Landscape fragmentation caused by roads, railway lines, extension of settlement areas, etc., further enhances the dispersion of pollutants and acoustic emissions and affects local climatic conditions, water balance, scenery, and land use. In this study, three new measures of fragmentation are introduced: degree of landscape division (D), splitting index (S), and effective mesh size (m). They characterize the anthropogenic penetration of landscapes from a geometric point of view and are calculated from the distribution function of the remaining patch sizes.First, D, S, and m are defined, their mathematical properties are discussed, and their reactions to the six fragmentation phases of perforation, incision, dissection, dissipation, shrinkage, and attrition are analysed. Then they are compared with five other known fragmentation indices with respect to nine suitability criteria such as intuitive interpretation, low sensivity to very small patches, monotonous reaction to different fragmentation phases, and detection of structural differences. Their ability to distinguish spatial patterns is illustrated by means of two series of model patterns. In particular, the effective mesh size (m), representing an intensive and area-proportionately additive measure, proves to be well suited for comparing the fragmentation of regions with differing total size. 相似文献
14.
Dispersal traits determine plant response to habitat connectivity in an urban landscape 总被引:1,自引:1,他引:0
Identification of trait syndromes that make species vulnerable to habitat fragmentation is essential in predicting biodiversity
change. Plants are considered particularly vulnerable if their capacities for persistence in and for dispersal among local
habitats are low. Here we investigated the influence of easily measured functional traits on the presence of 45 plant species
in an urban landscape in north-west Germany where patches were separated by distances consistent with regular plant dispersal
range. To describe the spatial configuration of patches we calculated species-specific patch connectivities. Then we assessed
plant connectivity responses in distribution models calculated from connectivities and environmental predictors. Twenty (45%)
of the analysed species showed a positive connectivity response after accounting for species-specific habitat requirements.
These species differed from non-responsive species by functional traits associated with dispersal, including reduced seed
numbers and higher terminal velocities relative to non-responsive species. Persistence traits played however no role which
we attribute to the environmental conditions of urban habitats and their spatiotemporal characteristics. Our study underlines
that even ruderal plants experience dispersal limitation and demonstrates that easily measured functional traits may be used
as indicators of fragmentation vulnerability in urban systems allowing generalizations to larger species sets. 相似文献
15.
Landscape Ecology - Habitat fragmentation can exacerbate the negative effects of habitat loss for some species. Mitigating fragmentation is difficult, however, because population responses depend... 相似文献
16.
基于Quick Bird卫星影像和地理信息系统,以ArcGIS 9.3和Fragstats 3.3为技术支撑,对不同建筑密度下的城市森林景观逆破碎化趋势下景观指数和植物群落特征变化进行分析,并对景观进行近自然度评价,进而找出达到近自然林属性的最低景观逆破碎化程度,即景观逆破碎化阈值。 相似文献
17.
Gestich Carla C. Arroyo-Rodrguez Vctor Saranholi Bruno H. da Cunha Rogrio G. T. Setz Eleonore Z. F. Ribeiro Milton C. 《Landscape Ecology》2022,37(1):147-157
Landscape Ecology - Forest loss and fragmentation are rapidly expanding across the tropics. Although forest loss is a major driver of the current biodiversity crisis, the effect of fragmentation... 相似文献
18.
19.
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
20.
Previous research has suggested that ducks and songbirds may benefit from prairie landscapes that consist primarily of contiguous
grasslands. However, the relative importance of landscape-level vs. local characteristics on mechanisms underlying observed
patterns is unclear. We measured effects of grassland amount and fragmentation on upland and wetland songbird and duck density
and nest success, and on some nest predators, across 16 landscapes in southern Alberta, Canada. We compared these landscape-level
effects with local-scale responses, including distance to various edges and vegetation characteristics. We also evaluated
several statistical approaches to comparing effects of habitat characteristics at multiple spatial scales. Few species were
influenced by grassland amount or fragmentation. In contrast, distance to edge and local vegetation characteristics had significant
effects on densities and nest success of many species. Previous studies that reported effects of landscape characteristics
may have detected patterns driven by local mechanisms. As a corollary, results were very sensitive to statistical model structure;
landscape level effects were much less apparent when local characteristics were included in the models. 相似文献