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1.
When habitats are lost, species are lost in the region as a result of the sampling process. However, it is less clear what happens to biodiversity in the habitats that remain. Some have argued that the main influence of habitat loss on biodiversity is simply due to the total amount of habitat being reduced, while others have argued that fragmentation leads to fewer species per site because of altered spatial connectance among extant habitats. Here, we use a unique data set on invertebrate species in ponds spanning six decades of habitat loss to show that both regional and local species richness declined, indicating that species loss is compounded by habitat loss via connectivity loss, and not a result of a sampling process or changes in local environmental conditions. Overall, our work provides some of the clearest evidence to date from a longitudinal study that habitat loss translates into species loss, even within the remaining habitats. 相似文献
2.
The impacts of tropical deforestation and forest degradation on SE Asia's biotas have been documented, but a quantitative synthesis is currently lacking. We examined the responses of biodiversity to anthropogenic forest disturbance by comparing key ecological attributes between undisturbed and neighboring disturbed forests. Based on data from four taxonomic groups (vascular plants, invertebrates, birds, and mammals), six broad measures of 'ecological health' ( e.g. , richness, abundance, and demographics), and a range of different impact types from 120 articles published, we calculated the proportion of pairwise comparisons in which the measure of ecological health was lower in impacted than in pristine sites, as would be expected if forest disturbance was detrimental. The explanatory power of correlates of disturbance sensitivity was assessed using an information-theoretic evaluation of a candidate set of generalized linear models (GLMs). Overall, 73.6 percent (95% CI = 70.8–76.2%) of 1074 pairwise comparisons supported the expectation that forest disturbance was detrimental to ecological health, with mammals being the most sensitive group. The median effect size was for pristine areas to have 22.2 percent higher ecological health than equivalent disturbed areas. The most responsive measure of ecological health was species richness (median = 28.6% higher in pristine), and agricultural areas were the most ecologically degraded (median = 35.6% higher in pristine). However, the GLMs revealed no marked differences overall between taxonomic groups, habitat impact types, or ecological health measures. Our finding implies that the sensitivity of biodiversity to forest disturbance is moderately high, but essentially universal, suggesting urgent forest conservation actions. 相似文献
3.
Ilkka Hanski 《Journal of Biogeography》2015,42(5):989-993
In a recent article in this journal, Fahrig (2013, Journal of Biogeography, 40 , 1649–1663) concludes that variation in species richness among sampling sites can be explained by the amount of habitat in the ‘local landscape’ around the sites, while the spatial configuration of habitat within the landscape makes little difference. This conclusion may be valid for small spatial scales and when the total amount of habitat is large, but modelling and empirical studies demonstrate adverse demographic consequences of fragmentation when there is little habitat across large areas. Fragmentation effects are best tested with studies on individual species rather than on communities, as the latter typically consist of species with dissimilar habitat requirements. The total amount of habitat and the degree of fragmentation tend to be correlated, which poses another challenge for empirical studies. I conclude that fragmentation poses an extra threat to biodiversity, in addition to the threat posed by loss of habitat area. 相似文献
4.
Jessica Kemper Richard M. Cowling David M. Richardson Greg G. Forsyth David H. McKelly 《Austral ecology》2000,25(2):179-186
The South Coast Renosterveld has been fragmented extensively by agriculture. The extent of this fragmentation in terms of overall habitat loss, fragment sizes and fragment numbers has not been described previously, thereby limiting the development of conservation strategies for this vegetation type. Patterns of renosterveld loss in three sectors along a west–east gradient were described using LANDSAT imagery and a Geographical Information System‐based program (FRAGSTATS) for spatial pattern analysis. These patterns were then correlated with rainfall and topography measures, which are indicators of agricultural potential. Over 80% of the South Coast Renosterveld has been cultivated. Fragmentation levels increased significantly from east to west, with 33% of natural vegetation remaining in the east and only 4% in the west. Topographical variables were the strongest predictors of patterns of renosterveld loss, with fragments being largely confined to slopes too steep for ploughing; they therefore face little risk of future cultivation. These results have implications for conservation planning options for the South Coast Renosterveld. There is the potential for large reserves in the east, as well as corridor reserves along major river valleys, but for only small, isolated reserves in the west. 相似文献
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6.
River damming causes ecosystem losses and habitat fragmentation. In the Cerrado, the flood affects mainly forested habitats in valleys. In 1996, the Tocantins River (Brazil) was dammed to create the Serra da Mesa hydroelectric plant, and 14 sites were monitored during flooding. Eight hills that formed islands were monitored with pitfall traps. Only one frog species was found on islands 3 yr after complete reservoir formation. Cerrado amphibians showed rapid decline during and after flooding. 相似文献
7.
The mechanisms underlying responses of invertebrates to forest edges remain poorly understood. Here, we use an experimental approach to investigate the predation rates on butterflies in two neotropical forest fragments. Neither distance from forest edge nor degree of forest openness affected predation rates on artificial caterpillars. The mean predation rate of artificial caterpillars on Barro Colorado Island (1500 ha) was significantly higher than that on Peninsula Gigante (2600 ha) likely due to density‐dependent effects. Our study demonstrates the utility of artificial predation experiments for rapid assessment of relative lepidoptera predation rates in tropical forests. 相似文献
8.
Crooks KR Burdett CL Theobald DM Rondinini C Boitani L 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2011,366(1578):2642-2651
Although mammalian carnivores are vulnerable to habitat fragmentation and require landscape connectivity, their global patterns of fragmentation and connectivity have not been examined. We use recently developed high-resolution habitat suitability models to conduct comparative analyses and to identify global hotspots of fragmentation and connectivity for the world's terrestrial carnivores. Species with less fragmentation (i.e. more interior high-quality habitat) had larger geographical ranges, a greater proportion of habitat within their range, greater habitat connectivity and a lower risk of extinction. Species with higher connectivity (i.e. less habitat isolation) also had a greater proportion of high-quality habitat, but had smaller, not larger, ranges, probably reflecting shorter distances between habitat patches for species with restricted distributions; such species were also more threatened, as would be expected given the negative relationship between range size and extinction risk. Fragmentation and connectivity did not differ among Carnivora families, and body mass was associated with connectivity but not fragmentation. On average, only 54.3 per cent of a species' geographical range comprised high-quality habitat, and more troubling, only 5.2 per cent of the range comprised such habitat within protected areas. Identification of global hotspots of fragmentation and connectivity will help guide strategic priorities for carnivore conservation. 相似文献
9.
Thomas J. Matthews H. Eden Cottee‐Jones Robert J. Whittaker 《Diversity & distributions》2014,20(10):1136-1146
10.
Josiane Ribolli Cláudio Manoel Rodrigues de Melo Evoy Zaniboni-Filho 《Genetics and molecular biology》2012,35(4):761-769
Freshwater fish present unique challenges when one attempts to understand the factors that determine the structure of their populations. Habitat fragmentation is a leading cause of population decline that threatens ecosystems worldwide. In this study, we investigated the conservation status of genetic variability in the Neotropical catfish (Pimelodus maculatus). Specifically, we examined the structure and genetic diversity of this species in a region of the Upper Uruguay River fragmented by natural barriers and dams. There was no genetic structure among the four sites analyzed, indicating the existence of only one population group. A combination of environmental management and genetic monitoring should be used to minimize the impact of impoundment on panmitic populations of migratory fish species. 相似文献
11.
PETER I. MACREADIE ROD M. CONNOLLY MICHAEL J. KEOUGH GREGORY P. JENKINS JEREMY S. HINDELL 《Austral ecology》2010,35(5):515-521
Ecological theory predicts that habitat growth and loss will have different effects on community structure, even if they produce patches of the same size. Despite this, studies on the effects of patchiness are often performed without prior knowledge of the processes responsible for the patchiness. We manipulated artificial seagrass habitat in temperate Australia to test whether fish and crustacean assemblages differed between habitats that formed via habitat loss and habitat growth. Habitat loss treatments (originally 16 m2) and habitat growth treatments (originally 0 m2) were manipulated over 1 week until each reached a final patch size of 4 m2. At this size, each was compared through time (0–14 days after manipulation) with control patches (4 m2 throughout the experiment). Assemblages differed significantly among treatments at 0 and 1 day after manipulation, with differences between growth and loss treatments contributing to most of the dissimilarity. Immediately after the final manipulation, total abundance in habitat loss treatments was 46% and 62% higher than controls and habitat growth treatments, respectively, which suggests that animals crowded into patches after habitat loss. In contrast to terrestrial systems, crowding effects were brief (≤1 day), signifying high connectivity in marine systems. Growth treatments were no different to controls, despite the lower probability of animals encountering patches during the growth phase. Our study shows that habitat growth and loss can cause short‐term differences in animal abundance and assemblage structure, even if they produce patches of the same size. 相似文献
12.
David N.M. Mbora Julie Wieczkowski Elephas Munene 《American journal of physical anthropology》2009,140(3):562-571
We investigated the effects of anthropogenic habitat degradation on group size, ranging, fecundity, and parasite dynamics in four groups of the Tana River mangabey (Cercocebus galeritus). Two groups occupied a forest disturbed by human activities, while the other two occupied a forest with no human disturbance. We predicted that the groups in the disturbed forest would be smaller, travel longer distances daily, and have larger home ranges due to low food tree abundance. Consequently, these groups would have lower fecundity and higher parasite prevalence and richness (number of parasite species). We measured the abundance of food trees and anthropogenic activity in the forests, the groups' daily travel distances and home range sizes, and censused social groups over 12 months. We also analyzed fecal samples for gastrointestinal parasites from three of the groups. The disturbed forest had a lower abundance of food trees, and groups in this forest traveled longer distances, had larger home range sizes, were smaller, and had lower fecundity. The groups in the disturbed forest had higher, although not statistically significant, parasite prevalence and richness. This study contributes to a better understanding of how anthropogenic habitat change influences fecundity and parasite infections in primates. Our results also emphasize the strong influence of habitat quality in determining daily travel distance and home range size in primates. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc. 相似文献
13.
生境破碎是生物多样性下降的主要原因之一。通常以岛屿生物地理学、异质种群生物学和景观生态学的理论来解释不同空间尺度中生境破碎化的生态学效应。生境破碎化引起面积效应、隔离效应和边缘效应。这些效应通过影响动物种群的绝灭阈值、分布和多度、种间关系以及生态系统过程,最终影响动物种群的存活。野外研究表明,破碎化对动物的影响,因物种、生境类型和地理区域不同而有所变化,因此,预测物种在破碎生境中的存活比较困难。研究热点集中于：确定生境面积损失和生境斑块的空间格局对破碎景观中物种绝灭的相对影响,破碎景观中物种的适宜生境比例和绝灭阈值,异质种群动态以及生态系统的生态过程。随着3S技术的发展,生境破碎化模型趋于复杂,而发展有效的模型和验证模型将成为一项富有挑战性的任务。 相似文献
14.
The fact that species vary in their vulnerability to extinction is well documented, but the reasons for these differences remain poorly understood. Why should some species/families/guilds decline rapidly with increasing anthropogenic disturbance, while others either tolerate or proliferate in disturbed habitats? We investigated the bird species composition in 31 primary forest patches of varying size in a region of the Amazonian 'Arc of Deforestation' and assessed which species life-history traits predisposed individual species to extinction. Medium-sized non-flocking canopy frugivores/ominvores of low primary forest dependence were least likely to go extinct in small patches, while small-bodied flock-following primary-forest-dependent terrestrial insectivores were most fragmentation sensitive. We found highly idiosyncratic relationships between the minimum size of forest patches occupied by different species and their territory size requirements estimated based on other Amazonian studies. This suggests that avian assemblages in forest fragments primarily comprise species that either have good dispersal abilities or are highly tolerant to the non-forest matrix, rather than those whose minimum spatial requirements can be met by the size of available forest fragments. 相似文献
15.
Adam S. Hadley Matthew G. Betts 《Biological reviews of the Cambridge Philosophical Society》2012,87(3):526-544
Animal‐mediated pollination is essential for both ecosystem services and conservation of global biodiversity, but a growing body of work reveals that it is negatively affected by anthropogenic disturbance. Landscape‐scale disturbance results in two often inter‐related processes: (1) habitat loss, (2) disruptions of habitat configuration (i.e. fragmentation). Understanding the relative effects of such processes is critical in designing effective management strategies to limit pollination and pollinator decline. We reviewed existing published work from 1989 to 2009 and found that only six of 303 studies considering the influence of landscape context on pollination separated the effects of habitat loss from fragmentation. We provide a synthesis of the current landscape, behavioural, and pollination ecology literature in order to present preliminary multiple working hypotheses explaining how these two landscape processes might independently influence pollination dynamics. Landscape disturbance primarily influences three components of pollination interactions: pollinator density, movement, and plant demography. We argue that effects of habitat loss on each of these components are likely to differ substantially from the effects of fragmentation, which is likely to be more complex and may influence each pollination component in contrasting ways. The interdependency between plants and animals inherent to pollination systems also has the possibility to drive cumulative effects of fragmentation, initiating negative feedback loops between animals and the plants they pollinate. Alternatively, due to their asymmetrical structure, pollination networks may be relatively robust to fragmentation. Despite the potential importance of independent effects of habitat fragmentation, its effects on pollination remain largely untested. We postulate that variation across studies in the effects of ‘fragmentation’ owes much to artifacts of the sampling regimes adopted, particularly (1) incorrectly separating fragmentation from habitat loss, and (2) mis‐matches in spatial scale between landscapes studied and the ecological processes of interest. The field of landscape pollination ecology could be greatly advanced through the consideration and quantification of the matrix, landscape functional connectivity, and pollinator movement behaviour in response to these elements. Studies designed to disentangle the independent effects of habitat loss and fragmentation are essential for gaining insight into landscape‐mediated pollination declines, implementing effective conservation measures, and optimizing ecosystem services in complex landscapes. 相似文献
16.
The effect of isolation and the importance of dispersal in establishing and maintaining populations in fragments of remnant habitat remain poorly understood. Nevertheless, environmental connectivity is likely to be important for ensuring the long‐term preservation of biodiversity in extensively cleared landscapes. In this study, we compared reptile communities in large conservation parks with those in small woodland remnants 6.5–12 km from the parks, on the Eyre Peninsula, South Australia, Australia. We assessed the impact of fragmentation on the abundance, richness and habitat preferences of reptiles, and examined whether connection to linear roadside vegetation altered reptile communities in small woodland remnants. Of the 31 reptile species, 12 were restricted to conservation parks and six to habitat fragments in farmland. There was a substantial reduction in reptile species richness and abundance in farmland fragments. Direct connection of remnant vegetation to roadside corridors did not affect abundance of common species in the farmland fragments, although species richness was lower in isolated remnants in one of our two study regions. The habitat preference of the scincid lizard Menetia greyii differed between farmland fragments, where they were regularly found on dunes and roadsides, and conservation parks, where they were rare and not detected on dunes. We suggest that habitat fragmentation may have altered interspecific interactions, enabling an expansion of habitat use in the farming landscape. Significantly lower abundance of four common species in farmland settings compared with reserves indicated that existing corridors and small fragments provide inadequate connectivity over larger distances. To counter this effect, large reserves may need to be less than 10 km apart. 相似文献
17.
W. TYLER McCRANEY GREG GOLDSMITH DAVID K. JACOBS ANDREW P. KINZIGER 《Molecular ecology》2010,19(16):3315-3327
Habitat fragmentation and its genetic consequences are a critically important issue in evaluating the evolutionary penalties of human habitat modification. Here, we examine the genetic structure and diversity in naturally subdivided and artificially fragmented populations of the endangered tidewater goby (Eucyclogobius newberryi), a small fish restricted to discrete coastal lagoons and estuaries in California, USA. We use five naturally fragmented coastal populations from a 300‐ km spatial scale as a standard to assess migration and drift relative to eight artificially fragmented bay populations from a 30‐ km spatial scale. Using nine microsatellite loci in 621 individuals, and a 522‐base fragment of mitochondrial DNA control region from 103 individuals, we found striking differences in the relative influences of migration and drift on genetic variation at these two scales. Overall, the artificially fragmented populations exhibited a consistent pattern of higher genetic differentiation and significantly lower genetic diversity relative to the naturally fragmented populations. Thus, even in a species characterized by habitat isolation and subdivision, further artificial fragmentation appears to result in substantial population genetic consequences and may not be sustainable. 相似文献
18.
Ecology Letters (2011) 14: 1025-1034 ABSTRACT: Evolutionary changes in natural populations are often so fast that the evolutionary dynamics may influence ecological population dynamics and vice versa. Here we construct an eco-evolutionary model for dispersal by combining a stochastic patch occupancy metapopulation model with a model for changes in the frequency of fast-dispersing individuals in local populations. We test the model using data on allelic variation in the gene phosphoglucose isomerase (Pgi), which is strongly associated with dispersal rate in the Glanville fritillary butterfly. Population-specific measures of immigration and extinction rates and the frequency of fast-dispersing individuals among the immigrants explained 40% of spatial variation in Pgi allele frequency among 97 local populations. The model clarifies the roles of founder events and gene flow in dispersal evolution and resolves a controversy in the literature about the consequences of habitat loss and fragmentation on the evolution of dispersal. 相似文献
19.
Alessio MORTELLITI Giovanni AMORI Dario CAPIZZI Carlo RONDININI Luigi BOITANI 《Mammal Review》2010,40(2):125-154
- 1 Habitat loss, habitat fragmentation and habitat degradation are the greatest threats to mammals in Europe and the rest of the world. Despite the fact that extensive literature exists, no comprehensive review or synthesis is available to date and this may slow down scientific progress and hamper conservation efforts.
- 2 The goal of this study is to understand if and in what direction progress has been made in the study of the effects of habitat loss and fragmentation on the spatial distribution of European terrestrial mammals. Firstly, we carry out a general synthesis which is structured around 11 key points. The aim of this point‐by‐point analysis is to identify trends, knowledge gaps and any significant bias in the available literature, and to highlight strengths and shortfalls of the different approaches which have to date been applied. Secondly, we follow a species‐specific systematic approach: for each species, we synthesise key results.
- 3 Our results show how substantial progress has been hampered for several reasons including: a large predominance of small‐scale field studies of short duration, and a generalised lack of control of: (i) confounding variables; (ii) spatial autocorrelation; and (iii) false absences. Also, despite the relatively high number of studies, few were theoretical studies and even fewer were meta‐analyses. The lack of meta‐analyses is likely to be due to the small amount of crucial details included in the publications, such as model parameters or information on the landscape context (such as the amount of residual forest cover).
- 4 We synthesise the main results for 14 species. The level of progress is highly variable: for some species, such as the red squirrel Sciurus vulgaris, a series of long‐term, large‐scale process‐oriented studies has allowed an in‐depth understanding of its ecology in fragmented landscapes. On the other hand, with other species such as the bank vole Myodes glareolus, despite a relatively large number of field studies, little progress has been made.
20.
栖息地破碎是生物多样性下降的主要原因之一。栖息地破碎引起的面积效应、隔离效应和边缘效应能影响动物种群的绝灭阈值、分布、多度、种间关系以及生态系统过程, 最终影响动物种群的数量分布。2006年10-11月和2007年10-11月, 利用全球定位系统(GPS)、地理信息系统(GIS)和样方法定量分析京杭运河邵伯至高邮段狗獾栖息地破碎化程度, 确定不同斑块的面积、斑块距离、斑块隔离度以及栖息地质量对斑块中狗獾数量分布的影响。结果表明, 各个斑块内狗獾的洞口数、粪堆数与该斑块的面积显著的正相关(r=0.961, P=0.039; r=0.999, P=0.023), 但与斑块距离、斑块隔离度无显著的相关性(P>0.05)。栖息地的质量也会影响狗獾的数量分布, 多元线性逐步回归分析表明, 人类干扰和与栖息地的郁闭性显著的影响狗獾的数量分布。以上结果说明, 京杭运河邵伯高邮段栖息地的破碎化程度对狗獾的数量分布还没有造成显著的直接影响, 但会间接降低栖息地的质量, 进而影响狗獾的生存。 相似文献