Habitat fragmentation has been a research hotspot of biodiversity,and an important "bottleneck" restricting biodiversity.Habitat fragmentation can cause species loss and affect the process of immigration and...Habitat fragmentation has been a research hotspot of biodiversity,and an important "bottleneck" restricting biodiversity.Habitat fragmentation can cause species loss and affect the process of immigration and colonization by decreasing habitat size and increasing isolation degree among populations,thereby affecting species diversity of animals and plants.This paper elaborated the concept and main theory of habitat fragmentation and the influence of habitat fragmentation on species diversity of animals and plants,and suggested that studies on the effects of habitat fragmentation on species diversity at multi-trophic levels and larger scales should be strengthened.展开更多
Due to human-caused deforestation,global warming,and other environmental factors,habitat fragmentation became widespread.This fragmentation has a variety of detrimental repercussions for many species as well as humans...Due to human-caused deforestation,global warming,and other environmental factors,habitat fragmentation became widespread.This fragmentation has a variety of detrimental repercussions for many species as well as humans,especially in the agricultural economy.It causes insect outbreaks,the expansion of alien species,and disrupts biological management by rendering the habitat unsuitable for natural enemies in agriculture.Providing natural enemies with additional food is one method to improve the ecosystem and support them.In this study,we assumed that the ecosystem is separated into two patches and that predators can easily migrate from one patch to the next,while prey stays inside its patch's territory.We looked at the impact of offering more food to predators in a patchy environment using dynamical systems theory.The permanence,stability,and various bifurcations that occur in the system are studied using a rigorous mathematical analysis.The study looks at how predator's access to other food sources affects pest management.By adjusting the provided food's characteristic qualities,such as(nutritional)quality and quantity,one can limit and manage the pest in one or both patches,as well as eliminate predators from the ecosystem.This research reveals that providing predators with additional food(of specified quality and quantity)can help in controlling chaotic behavior in the system.The findings of the study are supported by numerical simulations.展开更多
Aims The pine rocklands of southern Florida are a fire-dependent forest associated with outcrops of limestone.Pine rockland plants have sev-eral adaptations to fire,and for many species,burning increases plant growth,...Aims The pine rocklands of southern Florida are a fire-dependent forest associated with outcrops of limestone.Pine rockland plants have sev-eral adaptations to fire,and for many species,burning increases plant growth,flowering and seedling establishment.The pine rockland forest has been reduced and fragmented in recent decades.Outside of Everglades National Park,only 2%of the original pine rocklands remain,and they are in the form of small fragments.Our objective is to investigate the effects of fragmentation and habitat quality on abun-dance and plant reproductive fitness of Angadenia berteroi(A.D.C.)Miers,a threatened species of the southern Florida pine rockland.Methods We estimated the density of plants using a stratified random sam-pling design,and reproductive fitness(in terms of percentage of plants with flowers and fruit)by walking transects in an array of habitat fragments of different sizes and degrees of isolation(distance to the nearest fragment)as well as in continuous habitat.Structural equation modeling(SEM)was employed to investigate how A.berteroi reproductive fitness was affected by fragmentation and habitat quality.Important Findings Habitat fragment size was correlated with the density of A.berteroi,but did not have a great impact on its reproductive success.However,habitat quality represented by litter depth and subcan-opy cover had strong negative effects on the reproductive fitness of A.berteroi,suggesting that increased light availability and low litter cover resulting from recent fires may favor reproduction.展开更多
Aims This study aimed to examine the changes in plant species richness,frequency and density along a habitat fragmentation gradient(with varied degrees of habitat fragmentation[DHFs])in a desertified grass-land of Hor...Aims This study aimed to examine the changes in plant species richness,frequency and density along a habitat fragmentation gradient(with varied degrees of habitat fragmentation[DHFs])in a desertified grass-land of Horqin Sandy Land,northeastern Inner Mongolia,China.Methods In this study,six landscape plots(500×500 m each)along a habi-tat fragmentation gradient were established.A new fragmentation index was formulated to study the effects of habitat fragmentation on biodiversity indices(species richness,frequency and density).Regression analyses(linear-or non-linear regression)were con-ducted to assess the changes in species richness,frequency and density along the habitat fragmentation gradient at plant commu-nity,functional group and species scales,respectively.Important Findings There was a non-linear relationship(following a quadratic function)between total species richness and the DHF.Total species richness reached its peak when the DHF was 0.2,beyond which species richness decreased along the fragmentation gradient.Plant func-tional groups showed their specific responses to habitat fragmenta-tion,and some non-linear relationships and thresholds existed.The relative richness of rare species also showed a non-linear response to habitat fragmentation,with the threshold being DHF=0.6.Species became rarer(both some common species and rare spe-cies)with the intensifying habitat fragmentation.Our study dem-onstrates the importance of the non-linear relationships and plant functional groups in exploring the effects of habitat fragmentation on biodiversity and implementing effective biological conservation in sand dunes.展开更多
A growing number of studies have looked at how climate change alters the effects of habitat fragmentation and degradation on both single and multiple species;some raise concern that biodiversity loss and its effects w...A growing number of studies have looked at how climate change alters the effects of habitat fragmentation and degradation on both single and multiple species;some raise concern that biodiversity loss and its effects will be exacerbated.The published literature on spatial dynamics(such as dispersal and metapopulation dynamics),habitat fragmentation and climate change requires synthesis and a conceptual framework to simplify thinking.We propose a framework that integrates how climate change affects spatial population dynamics and the effects of habitat fragmentation in terms of:(i)habitat quality,quantity and distribution;(ii)habitat connectivity;and(iii)the dynamics of habitat itself.We use the framework to categorize existing autecological studies and investigate how each is affected by anthropogenic climate change.It is clear that a changing climate produces changes in the geographic distribution of climatic conditions,and the amount and quality of habitat.The most thorough published studies show how such changes impact metapopulation persistence,source-sink dynamics,changes in species’geographic range and community composition.Climate-related changes in movement behavior and quantity,quality and distribution of habitat have also produced empirical changes in habitat connectivity for some species.An underexplored area is how habitat dynamics that are driven by climatic processes will affect species that live in dynamic habitats.We end our discussion by suggesting ways to improve current attempts to integrate climate change,spatial population dynamics and habitat fragmentation effects,and suggest distinct areas of study that might provide opportunities for more fully integrative work.展开更多
Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctu...Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctuations to the composition of the landscape.It states that as ROMPA decreases(fragmentation increases),vole population fluctuations will increase(including the tendency to display multi-annual cycles in abundance)because decreased proportions of optimal habitat result in greater population declines and longer recovery time after a harsh season.To date,only comparative observations in the field have supported the hypothesis.This paper reports the results of the first experimental test.I used prairie voles,Microtus ochrogaster,and mowed grassland to create model landscapes with 3 levels of ROMPA(high with 25%mowed,medium with 50%mowed and low with 75%mowed).As ROMPA decreased,distances between patches of favorable habitat(high cover)increased owing to a greater proportion of unfavorable(mowed)habitat.Results from the first year with intensive live trapping indicated that the preconditions for operation of the hypothesis existed(inversely density dependent emigration and,as ROMPA decreased,increased per capita mortality and decreased per capita movement between optimal patches).Nevertheless,contrary to the prediction of the hypothesis that populations in landscapes with high ROMPA should have the lowest variability,5 years of trapping indicated that variability was lowest with medium ROMPA.The design of field experiments may never be perfect,but these results indicate that the ROMPA hypothesis needs further rigorous testing.展开更多
The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe e...The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe ecological threats due to the expansion of modern agriculture,extensive exploitation and consumption of natural resources,and excessive land development during its transition from an agricultural to a modern society.In response,China has implemented various ecological conservation measures,including habitat restoration and protection.These efforts have made substantial strides in biodiversity conservation,with certain regions witnessing an increase in primate populations.In the current study,we conducted a systematic review of historical documents and field research data related to Chinese primates,evaluating the endangered status of primate species in China.Despite improvements in the habitats of most primate species and some population growth,many species still face severe threats,including declining and small populations.Species such as the Myanmar snub-nosed monkey(Rhinopithecus strykeri),eastern black crested gibbon(Nomascus nasutus),and Hainan gibbon(N.hainanus)remain particularly vulnerable due to their limited distribution ranges and extremely small populations.Insufficient scientific data,fragmented information,and not enough studies in conservation biology further compound the challenges.Moreover,there is a notable lack of detailed population monitoring data for species such as the Bengal slow loris(Nycticebus bengalensis),pygmy slow loris(N.pygmaeus),Indochinese gray langur(Trachypithecus crepusculus),Shortridge’s langur(T.shortridgei),and capped langur(T.pileatus),which hinders the development of practical and targeted conservation management strategies.Therefore,for national biodiversity conservation,there is an urgent need for specialized primate surveys,enhancing habitat protection and restoration,and increasing focus on cross-border conservation strategies and regional cooperation.There is also a need to establish a comprehensive and systematic research database platform,conduct continuous and in-depth research in primate biology,and actively engage in the scientific assessment of ecotourism.Additionally,strengthening public awareness and education on wildlife conservation remains essential.Such integrated and systematic efforts will provide scientific support for the current and future conservation and management of primate species in China.展开更多
Hydropower development has become an important driver of habitat loss and fragmentation across lowland tropical forests.Despite ample evidence on the detrimental effects of insular habitat fragmentation on biodiversit...Hydropower development has become an important driver of habitat loss and fragmentation across lowland tropical forests.Despite ample evidence on the detrimental effects of insular habitat fragmentation on biodiversity,invertebrate taxa,that may be critical to ecosystem functioning,have been overlooked.We assessed the assemblage-level responses of social wasps to forest insularization induced by the Balbina Hydroelectric Dam in Central Brazilian Amazonia.Employing Malaise trapping,we captured wasps on 27 forest islands and three continuous forests.We constructed Generalized Linear Models and employed a model selection approach to examine the impact of local variables(fire severity(FIRE)and basal area of pioneer tree species(PIONEER))and landscape-scale variables(amount of habitat(COVER))on patterns of species richness,composition,and body size of wasps.A total of 374 individuals(29 species)were collected across all sampling sites.COVER was the main predictor of species richness,while PIONEER was the only variable that explained variation in community composition,with a negative effect on body size.Our results add evidence to the pervasive impacts of large hydroelectric dams on tropical forest biodiversity,and suggest that social wasps,among other invertebrates,can be used as bioindicators in infrastructure development projects.展开更多
A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 20...A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.展开更多
Habitat loss and fragmentation are mainly associated with population decrease of endangered species and biodiversity loss. The habitat suitability maps of red-crowned crane （Grusjaponensis） in 1992, 1999 and 2006 we...Habitat loss and fragmentation are mainly associated with population decrease of endangered species and biodiversity loss. The habitat suitability maps of red-crowned crane （Grusjaponensis） in 1992, 1999 and 2006 were produced by using Ecological Niche Suitability Model （ENSM） in Yellow River Delta Nature Reserve （118°33′-119°20′E longitude, 37°35′-38°12′N latitude）, Shandong Province, China. Based on the habitat suitability maps, the causation and change law of habitat loss and fragmentation of red-crowned crane were analyzed by selecting a series of landscape pattern indices. Results showed that due to scarcities of fresh water sources, habitat suitability of red-crowned crane in 1999 was inferior to that in 1992 and 2006 no matter whether human disturbances existed or not. Besides, human disturbance activities, especially road disturbances, increased rapidly during the period of 1992-2006. This worsened the habitat loss and frag- mentation of red-crowned crane, and led to degrading habitat suitability of red-crowned crane in 2006, compared with that in 1992. In conclusion, fresh water sources and human disturbance activities are the two main factors that drive the habitat suitability change of red-crowned crane.展开更多
Knowledge about plant diversity along disturbance gradients is essential for conservation and management of fragmented coastal habitats.This study examined the effects of human disturbance intensity in coastal habitat...Knowledge about plant diversity along disturbance gradients is essential for conservation and management of fragmented coastal habitats.This study examined the effects of human disturbance intensity in coastal habitats of Kuwait on diversity,composition,identity and assemblage of vascular plant species.Plant survey data from 113 plots （5m×5m each） were randomly selected in 51 sites at coastal fragmented habitats at three levels of disturbance intensities （high,moderate and low） and were statistically analyzed.The results revealed that about 76% of the recorded species are considered threatened species in Kuwait,most of which are being lost in high disturbed habitats.Disturbance led to the dominance of Zygophyllum qatarense,Cornulaca aucheri and Salsola imbricata,which are species of disturbance indicators.Richness,total plant cover and species diversity were higher in moderate and low disturbed habitats than in high disturbed habitats.Beta diversity between high and low disturbed habitats was higher than either between high and moderate,or between moderate and low disturbed habitats.Cluster analyses showed statistically significant differences in composition of plant assemblages,which indicate high beta diversity between the habitat types.Intensive urbanization and industrialization are among the most serious threats that contribute to declines in biological diversity and rapid fragmentation of coastal habitats in Kuwait.Establishing protective enclosures in the disturbed habitats,planting endangered and vulnerable species,and establishing a natural reserve at Nuwaiseeb are recommended conservation actions to avoid loss of the fragmented coastal habitats and to facilitate restoration of native plants.展开更多
The problem of habitat fragmentation is recently an important issue in ecological research as well as in the practical approach of nature conservation. According to the most popular approaches, habitats are considered...The problem of habitat fragmentation is recently an important issue in ecological research as well as in the practical approach of nature conservation. According to the most popular approaches, habitats are considered as the homogenous parts of the landscape. Also the metapopulation concept problem of the inert habitat heterogenity is considered quite seldom. These approaches have some weak points resulting from the assumption that the border between habitat patches and the metapopulation matrix is fairly sharp. This paper presents a resource-based concept of habitats, based on mathematical theory of point processes, which can be easily applied to analysing the problem of uneven distribution of resources. The basic assumption is that the random distribution of resources may be mathematically described as the realisation of a certain point process. According to our method, it is possible to calculate the expected quantities of available resources as well as the minimum area of habitat that includes the expected abundance of the resource. This approach may be very useful to understand some crucial phenomena in landscape ecology, such as the patch size effect and its connection to habitat loss and fragmentation.展开更多
The limestone region in southwestern Guangxi contains the most typical karst landforms in the world. Due to their destruction, the original forests mainly survive in nature reserves in the form of fragmented areas. Fr...The limestone region in southwestern Guangxi contains the most typical karst landforms in the world. Due to their destruction, the original forests mainly survive in nature reserves in the form of fragmented areas. From June 2009 to September 2010 we conducted an investigation of 13 relatively isolated habitats or sites, selected from each of the 13 nature reserves in southwestern Guangxi, with the least amount of anthropological activity and the largest presence of the original vegetation, in order to study the distribution of birds on forest fragments. The distribution patterns of the birds and the factors which affect them were analyzed by using the 'BINMATNEST' software and the Spearman’s rank correlation analysis, to determine: 1) whether nested patterns of birds in the karst area of southwestern Guangxi exist or not and 2) which factors are correlated with the nested patterns and the effect of these factors on forming nested patterns. The results show that the birds had statistically significant nested patterns in the karst area and the specificity of the habitat of the birds had a significant effect on the nested patterns. We suggest possible reasons for these results, based on the characteristics of the seasonal tropical rain forests in the study area and on neutral theory. We also urgently recommend that close attention be paid to the protection of the diversity of the environment for birds in all fragmented habitats.展开更多
The Chinese Grouse (Tetrastes sewerzowi) is a rare, endemic bird in China, inhabiting conifer-dominated mountain forests. Both the natural fragmentation and heavy cutting of mature forests have resulted in patchy grou...The Chinese Grouse (Tetrastes sewerzowi) is a rare, endemic bird in China, inhabiting conifer-dominated mountain forests. Both the natural fragmentation and heavy cutting of mature forests have resulted in patchy grouse habitats. We used SPOT (XS-sensor) satellite imagery to discriminate between open land and conifer or broadleaf forests. The area analyzed is about 120000 ha in size and includes the Lianhuashan Nature Reserve and the Yeliguan Forestry Park. We identiifed 4111 ha of mature coniferous forests in 229 patches (maximum 332 ha, mean 18 ha) as the habitat used by Chinese Grouse throughout the year. We examined 31 forest islands of different sizes and degrees of isolation for the presence of Chinese Grouse. We used generalized linear models (GLM) with binomial error structure and logit link function to estimate the probability of Chinese Grouse occupancy in a forest fragment. Habitat patch size (hs) and distance to the next occupied fragment (doc) were used as predictor variables, important for occupancy. Small habitat islands were disproportionately less likely to be occupied than large, nearby habitats. There was a clear speciifc habitat size of about 40 ha, above which habitat fragments were occupied more often. Suitable habitat fragments isolated by more than 2 km appeared to be inaccessible to Chinese Grouse. The results have been used in reforestation projects to establish linking corridors in the study area.展开更多
Background: The Hainan Partridge(Arborophila ardens) is endemic to Hainan Island,China,and is listed as vulnerable(VU) because its population size is steadily decreasing due to illegal hunting and habitat loss.Its bre...Background: The Hainan Partridge(Arborophila ardens) is endemic to Hainan Island,China,and is listed as vulnerable(VU) because its population size is steadily decreasing due to illegal hunting and habitat loss.Its breeding biology is poorly known.Methods: This study was conducted in three sites in the major tropical primary rainforest in Hainan.Nests of the Hainan Partridge were found by monitoring radio-tracked individuals.Video recorders were set up to monitor reproductive behaviour of Hainan Partridge when nests were found.Results: Here for the first time we report the breeding biology of Hainan Partridge by providing information on its nest site,nest,eggs,and reproductive behaviour.We found that Hainan Partridges laid immaculate white eggs in ground nests which were totally covered by dry leaves and small branches forming arches that provided optimal concealment.A novel and regular behaviour was found in Hainan Partridges since they grasped leaves and small branches and then threw them on or around their nests to provide cover during incubation and after hatching of chicks.Conclusions: Recruitment behaviour in Hainan Partridges benefit from supplementation of nest arch material to nests,cover the nest entrance and thus maintain or increase nest concealment.However,it may also contribute to concealment of the track which could expose their activities and clues for predators.Our finding implies that the Hainan Partridge has evolved such a novel reproductive behaviour under the strong selection of predation pressure.Due to habitat fragmentation and habitat loss,we suggest setting up arch structures and provide small branches and leaves in degraded or fragmented habitats to improve their suitability for partridge reproduction.This method may contribute to increasing the reproductive success of Hainan Partridge and thus compensate for its continuous population decrease.展开更多
Background:The Rufous-backed Bunting,Emberiza jankowskii,is an endangered species that is primarily distributed in Inner Mongolia,China.The main threats to the continued persistence of this species are habitat loss an...Background:The Rufous-backed Bunting,Emberiza jankowskii,is an endangered species that is primarily distributed in Inner Mongolia,China.The main threats to the continued persistence of this species are habitat loss and degradation.However,the impact of population loss on genetic diversity remains unclear.To support future conservation and management efforts,we assessed the genetic diversity and population structure of E.jankowskii using mitochondrial DNA and microsatellites.Methods:Blood samples were collected from 7-8-day-old nestlings in Inner Mongolia,China between May and August of 2012 and 2013.Mitochondrial DNA sequences and microsatellite markers were used to assess the genetic diversity,genetic structure and inbreeding of E.jankowskii.The results of genetic diversity and inbreeding were compared to other avian species.Results:We found an unexpectedly high level of genetic diversity in terms of mitochondrial DNA and microsatellite compared to other avian species.However,there were high levels of gene flow and minimal genetic structuring,among the fragmented breeding populations of E.jankowskii in Inner Mongolia.These findings suggest that E.jankowskii in Inner Mongolia is a metapopulation.Despite the high genetic diversity of E.jankowskii,local populations in each small patch remain at risk of extinction due to habitat loss.In addition,the E.jankowskii population has a high risk of inbreeding.Conclusions:To minimize further loss of genetic diversity of this endangered species,we suggest that the E.jankowskii in Inner Mongolia should be considered as a protected species for management purposes.Conservation efforts should concentrate on E.jankowskii habitat management.This may be most effectively achieved by protecting the current breeding habitats and prohibiting over-grazing.展开更多
Introduction:Deforestation significantly impacts large carnivores that depend on large tracts of interconnected forest habitat and that are sensitive to human activities.Understanding the relationship between habitat ...Introduction:Deforestation significantly impacts large carnivores that depend on large tracts of interconnected forest habitat and that are sensitive to human activities.Understanding the relationship between habitat use and spatial distribution of such species across human modified landscapes is critical when planning effective conservation strategies.This study assessed the presence of potential landscape connectivity thresholds resulting from habitat fragmentation associated with different deforestation patterns using a scale-based approach that links species-specific home ranges with the extent of anthropogenic activities.The objectives were(1)to quantify the spatial and temporal distribution of natural vegetation for five common deforestation patterns and(2)to evaluate the connectivity associated with these patterns and the existence of potential thresholds affecting jaguar dispersal.The Bolivian lowlands,located within jaguar conservation units,were analysed with landscape metrics to capture the spatial and temporal changes within deforested areas and to determine potential impact on jaguar connectivity and connectivity thresholds for dispersal.Results:Over the period of 1976–2005,the amount of natural vegetation has decreased by more than 40%in all locations with the biggest changes occurring between 1991 and 2000.Landscape spatial structure around jaguar locations showed that jaguars used areas with mean proportion of natural areas=83.14%(SE=3.72%),mean patch density=1.16 patches/100 ha(SE=0.28 patches/100 ha),mean patch area=616.95 ha(SE=172.89 ha)and mean edge density=705.27 m/ha(SE=182.19 m/ha).We observed strong fragmentation processes in all study locations,which has resulted in the connectivity of jaguar habitat decreasing to<20%by 2005.A connectivity threshold zone was observed when the proportion of natural vegetation was less than 58.4%(SE=1.3).Conclusions:Assessing fragmentation and connectivity for carnivores within the extent of human-modified landscapes proved to be an effective way to understand the changes caused by deforestation and their potential effects on large carnivore habitats.Our study highlights the importance of scale-based approaches for assessing current conservation challenges to protect large carnivores.展开更多
The giant panda faces severe threats from habitat fragmentation and isolation.Currently,giant panda populations have been fragmented into 30 habitat patches.The disappearance of isolated small populations and studies ...The giant panda faces severe threats from habitat fragmentation and isolation.Currently,giant panda populations have been fragmented into 30 habitat patches.The disappearance of isolated small populations and studies on the genetic diversity of various populations have shown that small isolated panda populations are at a high risk of dying out completely.Habitat fragmentation has seriously impaired the ability of the giant panda to resist climate changes and other natural disasters,such as large-scale,synchronous bamboo blooming.The Min Mountains have the largest population of pandas in China,numbering 581 individuals and accounting for 52%of the total(1114)in China.Geographic isolation means that giant pandas in the Min Mountains are divided into two populations(population A in the north and population B in the south).Population B,which had only 42 individuals in 1989,is severely threatened by high-density human populations and the loss of genetic diversity.However,we have identified an important corridor connecting the two populations.This paper explains the importance and the feasibility of reestablishing this corridor.Due to the special geographic locations of these two populations(two rivers block the migration of giant pandas between south and north),the corridor is the only passage for giant pandas in the region.Recent studies have also shown an increase of giant panda activity in the area of the corridor.However,vegetation in the corridor has been severely degraded.Bamboo forest must be restored in this area to provide food for the pandas during migration.The effects of human activities must be reduced in order to maintain panda habitat.We believe that a restored corridor will be of great benefit to the survival of giant pandas in the Min Mountains,especially for population B.Successful re-establishment of a corridor will be a valuable model for corridor construction in the future.展开更多
Background The topology of the plant-pollinator network can be explained by the species’abundance and their random interactions.Plant-pollinator networks can be studied in the context of a landscape,because each patc...Background The topology of the plant-pollinator network can be explained by the species’abundance and their random interactions.Plant-pollinator networks can be studied in the context of a landscape,because each patch can accommodate a certain local network.Local populations of pollinators in the landscape can be connected through migration and then constitute a metanetwork that is known as a combination of spatial and ecological networks.In this regard,habitat fragmentation can affect the topology of plant-pollinator metanetworks through changes in the species abundance and limiting their interactions.However,it is not clear what pattern(fragmented or aggregated)of the landscape structure can accommodate networks with a higher degree of specialization.Methods we created simulated landscapes with different forest proportions scenarios(from 5%to 50%of the total landscape)and degrees of fragmentation.Then,for each landscape,we limited the proportion of pollinators to the forest patch.We assumed that plants and pollinators are randomly distributed around the landscape and interact randomly.We used landscape metrics to measure different aspects of landscape structure and bipartite metrics for calculating the degree of specialization in plant-pollinator networks.Results The statistical relationship between bipartite and landscape metrics showed that the relationship between the topology of plant-pollinator networks and the landscape structure is affected by the forest amount in the landscape and the degree of forest fragmentation.We also found that according to the nestedness and H2(a measure of specialization)metrics,fragmented landscapes contain more general plant-pollinator networks.Conclusions Our findings suggest that fragmented landscapes,characterized by scattered forest patches,can promote higher levels of interaction between limited pollinators and diverse flowers,leading to more general plant-pollinator networks.展开更多
Riverscape connectivity is a critically important component determining the ecological condition of lotic ecosystems.We evaluated changes in fish assemblages caused by the loss of connectivity by mine tailings storage...Riverscape connectivity is a critically important component determining the ecological condition of lotic ecosystems.We evaluated changes in fish assemblages caused by the loss of connectivity by mine tailings storage dams(TSDs),hypothesizing that headwater fish assemblages are restructured by TSDs located downstream,even though the upstream habitats are not altered.We used standard methods to collect fish in 24 first to third order sites,with half draining to TSDs(dammed)and the other half free from this impact(undammed).To identify differences between treatments,we used PERMANOVA to test both environmental variables and ichthyofauna composition(Bray-Curtis similarity index)and evaluated the biological metrics that most influenced assemblage composition change.As expected,we observed no difference between treatments for environmental variables,but we did observe differences in fish assemblage composition.We also observed five metrics with lower values in dammed streams(richness and abundance of intolerant species,siluriform richness,and abundance of Pareiorhaphis cf.proskynita and Trichomycterus brasiliensis)and two metrics with higher values in dammed streams(perciform richness and abundance of Oligosarcus argenteus).We believe these changes resulted from of stream fragmentation by TSDs,in addition to source-sink mechanisms and conclude that mine TSDs located downstream change headwater fish assemblages,an impact often neglected in biomonitoring and bioassessment studies.展开更多
文摘Habitat fragmentation has been a research hotspot of biodiversity,and an important "bottleneck" restricting biodiversity.Habitat fragmentation can cause species loss and affect the process of immigration and colonization by decreasing habitat size and increasing isolation degree among populations,thereby affecting species diversity of animals and plants.This paper elaborated the concept and main theory of habitat fragmentation and the influence of habitat fragmentation on species diversity of animals and plants,and suggested that studies on the effects of habitat fragmentation on species diversity at multi-trophic levels and larger scales should be strengthened.
文摘Due to human-caused deforestation,global warming,and other environmental factors,habitat fragmentation became widespread.This fragmentation has a variety of detrimental repercussions for many species as well as humans,especially in the agricultural economy.It causes insect outbreaks,the expansion of alien species,and disrupts biological management by rendering the habitat unsuitable for natural enemies in agriculture.Providing natural enemies with additional food is one method to improve the ecosystem and support them.In this study,we assumed that the ecosystem is separated into two patches and that predators can easily migrate from one patch to the next,while prey stays inside its patch's territory.We looked at the impact of offering more food to predators in a patchy environment using dynamical systems theory.The permanence,stability,and various bifurcations that occur in the system are studied using a rigorous mathematical analysis.The study looks at how predator's access to other food sources affects pest management.By adjusting the provided food's characteristic qualities,such as(nutritional)quality and quantity,one can limit and manage the pest in one or both patches,as well as eliminate predators from the ecosystem.This research reveals that providing predators with additional food(of specified quality and quantity)can help in controlling chaotic behavior in the system.The findings of the study are supported by numerical simulations.
基金Funding was provided to Beyte Barrios by The Florida Native Plant Society(2008 Endowment Research Grant)FIU Kelly Scholarships(2008,2009,2012,2013)+1 种基金the Catherine H.Beattie Fellowship(2009)from The Garden Club of Americaa Florida International University Doctoral Evidence Acquisition Fellowship(2014).Collections were made under permit#0080 from Natural Areas Management,Miami-Dade County and Everglades National Park Scientific research and collection permit#EVER-2013-SCI-0030.This is contribution#316 to the Tropical Biology Program and#785 to the Southeast Environmental Research Center(SERC)at Florida International University.
文摘Aims The pine rocklands of southern Florida are a fire-dependent forest associated with outcrops of limestone.Pine rockland plants have sev-eral adaptations to fire,and for many species,burning increases plant growth,flowering and seedling establishment.The pine rockland forest has been reduced and fragmented in recent decades.Outside of Everglades National Park,only 2%of the original pine rocklands remain,and they are in the form of small fragments.Our objective is to investigate the effects of fragmentation and habitat quality on abun-dance and plant reproductive fitness of Angadenia berteroi(A.D.C.)Miers,a threatened species of the southern Florida pine rockland.Methods We estimated the density of plants using a stratified random sam-pling design,and reproductive fitness(in terms of percentage of plants with flowers and fruit)by walking transects in an array of habitat fragments of different sizes and degrees of isolation(distance to the nearest fragment)as well as in continuous habitat.Structural equation modeling(SEM)was employed to investigate how A.berteroi reproductive fitness was affected by fragmentation and habitat quality.Important Findings Habitat fragment size was correlated with the density of A.berteroi,but did not have a great impact on its reproductive success.However,habitat quality represented by litter depth and subcan-opy cover had strong negative effects on the reproductive fitness of A.berteroi,suggesting that increased light availability and low litter cover resulting from recent fires may favor reproduction.
基金This study was financially supported by National Natural Science Foundation of China(31600443,41501573)。
文摘Aims This study aimed to examine the changes in plant species richness,frequency and density along a habitat fragmentation gradient(with varied degrees of habitat fragmentation[DHFs])in a desertified grass-land of Horqin Sandy Land,northeastern Inner Mongolia,China.Methods In this study,six landscape plots(500×500 m each)along a habi-tat fragmentation gradient were established.A new fragmentation index was formulated to study the effects of habitat fragmentation on biodiversity indices(species richness,frequency and density).Regression analyses(linear-or non-linear regression)were con-ducted to assess the changes in species richness,frequency and density along the habitat fragmentation gradient at plant commu-nity,functional group and species scales,respectively.Important Findings There was a non-linear relationship(following a quadratic function)between total species richness and the DHF.Total species richness reached its peak when the DHF was 0.2,beyond which species richness decreased along the fragmentation gradient.Plant func-tional groups showed their specific responses to habitat fragmenta-tion,and some non-linear relationships and thresholds existed.The relative richness of rare species also showed a non-linear response to habitat fragmentation,with the threshold being DHF=0.6.Species became rarer(both some common species and rare spe-cies)with the intensifying habitat fragmentation.Our study dem-onstrates the importance of the non-linear relationships and plant functional groups in exploring the effects of habitat fragmentation on biodiversity and implementing effective biological conservation in sand dunes.
文摘A growing number of studies have looked at how climate change alters the effects of habitat fragmentation and degradation on both single and multiple species;some raise concern that biodiversity loss and its effects will be exacerbated.The published literature on spatial dynamics(such as dispersal and metapopulation dynamics),habitat fragmentation and climate change requires synthesis and a conceptual framework to simplify thinking.We propose a framework that integrates how climate change affects spatial population dynamics and the effects of habitat fragmentation in terms of:(i)habitat quality,quantity and distribution;(ii)habitat connectivity;and(iii)the dynamics of habitat itself.We use the framework to categorize existing autecological studies and investigate how each is affected by anthropogenic climate change.It is clear that a changing climate produces changes in the geographic distribution of climatic conditions,and the amount and quality of habitat.The most thorough published studies show how such changes impact metapopulation persistence,source-sink dynamics,changes in species’geographic range and community composition.Climate-related changes in movement behavior and quantity,quality and distribution of habitat have also produced empirical changes in habitat connectivity for some species.An underexplored area is how habitat dynamics that are driven by climatic processes will affect species that live in dynamic habitats.We end our discussion by suggesting ways to improve current attempts to integrate climate change,spatial population dynamics and habitat fragmentation effects,and suggest distinct areas of study that might provide opportunities for more fully integrative work.
文摘Increased habitat fragmentation leads to smaller size of habitat patches and to greater distance between patches.The ROMPA hypothesis(ratio of optimal to marginal patch area)uniquely links vole population fluctuations to the composition of the landscape.It states that as ROMPA decreases(fragmentation increases),vole population fluctuations will increase(including the tendency to display multi-annual cycles in abundance)because decreased proportions of optimal habitat result in greater population declines and longer recovery time after a harsh season.To date,only comparative observations in the field have supported the hypothesis.This paper reports the results of the first experimental test.I used prairie voles,Microtus ochrogaster,and mowed grassland to create model landscapes with 3 levels of ROMPA(high with 25%mowed,medium with 50%mowed and low with 75%mowed).As ROMPA decreased,distances between patches of favorable habitat(high cover)increased owing to a greater proportion of unfavorable(mowed)habitat.Results from the first year with intensive live trapping indicated that the preconditions for operation of the hypothesis existed(inversely density dependent emigration and,as ROMPA decreased,increased per capita mortality and decreased per capita movement between optimal patches).Nevertheless,contrary to the prediction of the hypothesis that populations in landscapes with high ROMPA should have the lowest variability,5 years of trapping indicated that variability was lowest with medium ROMPA.The design of field experiments may never be perfect,but these results indicate that the ROMPA hypothesis needs further rigorous testing.
基金supported by the National Natural Science Foundation of China(32371563)and Strategic Priority Research Program of the Chinese Academy of Sciences(XDB31020302)。
文摘The dual impact of climate change and human activities has precipitated a sharp decline in primate biodiversity globally.China is home to the most diverse primate species in the Northern hemisphere,which face severe ecological threats due to the expansion of modern agriculture,extensive exploitation and consumption of natural resources,and excessive land development during its transition from an agricultural to a modern society.In response,China has implemented various ecological conservation measures,including habitat restoration and protection.These efforts have made substantial strides in biodiversity conservation,with certain regions witnessing an increase in primate populations.In the current study,we conducted a systematic review of historical documents and field research data related to Chinese primates,evaluating the endangered status of primate species in China.Despite improvements in the habitats of most primate species and some population growth,many species still face severe threats,including declining and small populations.Species such as the Myanmar snub-nosed monkey(Rhinopithecus strykeri),eastern black crested gibbon(Nomascus nasutus),and Hainan gibbon(N.hainanus)remain particularly vulnerable due to their limited distribution ranges and extremely small populations.Insufficient scientific data,fragmented information,and not enough studies in conservation biology further compound the challenges.Moreover,there is a notable lack of detailed population monitoring data for species such as the Bengal slow loris(Nycticebus bengalensis),pygmy slow loris(N.pygmaeus),Indochinese gray langur(Trachypithecus crepusculus),Shortridge’s langur(T.shortridgei),and capped langur(T.pileatus),which hinders the development of practical and targeted conservation management strategies.Therefore,for national biodiversity conservation,there is an urgent need for specialized primate surveys,enhancing habitat protection and restoration,and increasing focus on cross-border conservation strategies and regional cooperation.There is also a need to establish a comprehensive and systematic research database platform,conduct continuous and in-depth research in primate biology,and actively engage in the scientific assessment of ecotourism.Additionally,strengthening public awareness and education on wildlife conservation remains essential.Such integrated and systematic efforts will provide scientific support for the current and future conservation and management of primate species in China.
基金supported by a NERC grant to C.A.P.(NE/J01401X/1)a Science Without Borders postdoctoral fellowship awarded to D.S.(CNPq grant 246975/2012-1)+1 种基金M.B.received a productivity grant from CNPq(304189/2022-7)supported by the inaugural Frontiers Planet Prize。
文摘Hydropower development has become an important driver of habitat loss and fragmentation across lowland tropical forests.Despite ample evidence on the detrimental effects of insular habitat fragmentation on biodiversity,invertebrate taxa,that may be critical to ecosystem functioning,have been overlooked.We assessed the assemblage-level responses of social wasps to forest insularization induced by the Balbina Hydroelectric Dam in Central Brazilian Amazonia.Employing Malaise trapping,we captured wasps on 27 forest islands and three continuous forests.We constructed Generalized Linear Models and employed a model selection approach to examine the impact of local variables(fire severity(FIRE)and basal area of pioneer tree species(PIONEER))and landscape-scale variables(amount of habitat(COVER))on patterns of species richness,composition,and body size of wasps.A total of 374 individuals(29 species)were collected across all sampling sites.COVER was the main predictor of species richness,while PIONEER was the only variable that explained variation in community composition,with a negative effect on body size.Our results add evidence to the pervasive impacts of large hydroelectric dams on tropical forest biodiversity,and suggest that social wasps,among other invertebrates,can be used as bioindicators in infrastructure development projects.
基金Under the auspices of Major State Basic Research Development Program of China (973 Progrom) (No 2007CB106801)National Key Technology R&D Program of China (No 2006BAD16B06)National Natural Science Foundation of China (No 30470180,30770397)
文摘A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.
基金the research was supported by National Natural Science Foundation (No. 40771172)Knowledge innovation project of the Chinese Academy of Sciences (No. kzcx2-yw-308)
文摘Habitat loss and fragmentation are mainly associated with population decrease of endangered species and biodiversity loss. The habitat suitability maps of red-crowned crane （Grusjaponensis） in 1992, 1999 and 2006 were produced by using Ecological Niche Suitability Model （ENSM） in Yellow River Delta Nature Reserve （118°33′-119°20′E longitude, 37°35′-38°12′N latitude）, Shandong Province, China. Based on the habitat suitability maps, the causation and change law of habitat loss and fragmentation of red-crowned crane were analyzed by selecting a series of landscape pattern indices. Results showed that due to scarcities of fresh water sources, habitat suitability of red-crowned crane in 1999 was inferior to that in 1992 and 2006 no matter whether human disturbances existed or not. Besides, human disturbance activities, especially road disturbances, increased rapidly during the period of 1992-2006. This worsened the habitat loss and frag- mentation of red-crowned crane, and led to degrading habitat suitability of red-crowned crane in 2006, compared with that in 1992. In conclusion, fresh water sources and human disturbance activities are the two main factors that drive the habitat suitability change of red-crowned crane.
文摘Knowledge about plant diversity along disturbance gradients is essential for conservation and management of fragmented coastal habitats.This study examined the effects of human disturbance intensity in coastal habitats of Kuwait on diversity,composition,identity and assemblage of vascular plant species.Plant survey data from 113 plots （5m×5m each） were randomly selected in 51 sites at coastal fragmented habitats at three levels of disturbance intensities （high,moderate and low） and were statistically analyzed.The results revealed that about 76% of the recorded species are considered threatened species in Kuwait,most of which are being lost in high disturbed habitats.Disturbance led to the dominance of Zygophyllum qatarense,Cornulaca aucheri and Salsola imbricata,which are species of disturbance indicators.Richness,total plant cover and species diversity were higher in moderate and low disturbed habitats than in high disturbed habitats.Beta diversity between high and low disturbed habitats was higher than either between high and moderate,or between moderate and low disturbed habitats.Cluster analyses showed statistically significant differences in composition of plant assemblages,which indicate high beta diversity between the habitat types.Intensive urbanization and industrialization are among the most serious threats that contribute to declines in biological diversity and rapid fragmentation of coastal habitats in Kuwait.Establishing protective enclosures in the disturbed habitats,planting endangered and vulnerable species,and establishing a natural reserve at Nuwaiseeb are recommended conservation actions to avoid loss of the fragmented coastal habitats and to facilitate restoration of native plants.
基金funded by Institute of Nature Conservation PASpartly by a Polish State Committee for Scientific Research/National Science Centre grant No.N N304 325836.
文摘The problem of habitat fragmentation is recently an important issue in ecological research as well as in the practical approach of nature conservation. According to the most popular approaches, habitats are considered as the homogenous parts of the landscape. Also the metapopulation concept problem of the inert habitat heterogenity is considered quite seldom. These approaches have some weak points resulting from the assumption that the border between habitat patches and the metapopulation matrix is fairly sharp. This paper presents a resource-based concept of habitats, based on mathematical theory of point processes, which can be easily applied to analysing the problem of uneven distribution of resources. The basic assumption is that the random distribution of resources may be mathematically described as the realisation of a certain point process. According to our method, it is possible to calculate the expected quantities of available resources as well as the minimum area of habitat that includes the expected abundance of the resource. This approach may be very useful to understand some crucial phenomena in landscape ecology, such as the patch size effect and its connection to habitat loss and fragmentation.
基金financed by the National Nature Science Foundation of China (Grant Nos. 30970381,31172123)
文摘The limestone region in southwestern Guangxi contains the most typical karst landforms in the world. Due to their destruction, the original forests mainly survive in nature reserves in the form of fragmented areas. From June 2009 to September 2010 we conducted an investigation of 13 relatively isolated habitats or sites, selected from each of the 13 nature reserves in southwestern Guangxi, with the least amount of anthropological activity and the largest presence of the original vegetation, in order to study the distribution of birds on forest fragments. The distribution patterns of the birds and the factors which affect them were analyzed by using the 'BINMATNEST' software and the Spearman’s rank correlation analysis, to determine: 1) whether nested patterns of birds in the karst area of southwestern Guangxi exist or not and 2) which factors are correlated with the nested patterns and the effect of these factors on forming nested patterns. The results show that the birds had statistically significant nested patterns in the karst area and the specificity of the habitat of the birds had a significant effect on the nested patterns. We suggest possible reasons for these results, based on the characteristics of the seasonal tropical rain forests in the study area and on neutral theory. We also urgently recommend that close attention be paid to the protection of the diversity of the environment for birds in all fragmented habitats.
基金supported by the National Natural Science Foundation of China(Grant No.31270468,30620130110)
文摘The Chinese Grouse (Tetrastes sewerzowi) is a rare, endemic bird in China, inhabiting conifer-dominated mountain forests. Both the natural fragmentation and heavy cutting of mature forests have resulted in patchy grouse habitats. We used SPOT (XS-sensor) satellite imagery to discriminate between open land and conifer or broadleaf forests. The area analyzed is about 120000 ha in size and includes the Lianhuashan Nature Reserve and the Yeliguan Forestry Park. We identiifed 4111 ha of mature coniferous forests in 229 patches (maximum 332 ha, mean 18 ha) as the habitat used by Chinese Grouse throughout the year. We examined 31 forest islands of different sizes and degrees of isolation for the presence of Chinese Grouse. We used generalized linear models (GLM) with binomial error structure and logit link function to estimate the probability of Chinese Grouse occupancy in a forest fragment. Habitat patch size (hs) and distance to the next occupied fragment (doc) were used as predictor variables, important for occupancy. Small habitat islands were disproportionately less likely to be occupied than large, nearby habitats. There was a clear speciifc habitat size of about 40 ha, above which habitat fragments were occupied more often. Suitable habitat fragments isolated by more than 2 km appeared to be inaccessible to Chinese Grouse. The results have been used in reforestation projects to establish linking corridors in the study area.
基金supported by the National Natural Science Foundation of China(Nos.30360015 and 30860044 to WL)National Geographic Society(NGS)Conservation Trust(C66-05 to WL)Program for New Century Excellent Talents in University(NCET-13-0761 to CY)
文摘Background: The Hainan Partridge(Arborophila ardens) is endemic to Hainan Island,China,and is listed as vulnerable(VU) because its population size is steadily decreasing due to illegal hunting and habitat loss.Its breeding biology is poorly known.Methods: This study was conducted in three sites in the major tropical primary rainforest in Hainan.Nests of the Hainan Partridge were found by monitoring radio-tracked individuals.Video recorders were set up to monitor reproductive behaviour of Hainan Partridge when nests were found.Results: Here for the first time we report the breeding biology of Hainan Partridge by providing information on its nest site,nest,eggs,and reproductive behaviour.We found that Hainan Partridges laid immaculate white eggs in ground nests which were totally covered by dry leaves and small branches forming arches that provided optimal concealment.A novel and regular behaviour was found in Hainan Partridges since they grasped leaves and small branches and then threw them on or around their nests to provide cover during incubation and after hatching of chicks.Conclusions: Recruitment behaviour in Hainan Partridges benefit from supplementation of nest arch material to nests,cover the nest entrance and thus maintain or increase nest concealment.However,it may also contribute to concealment of the track which could expose their activities and clues for predators.Our finding implies that the Hainan Partridge has evolved such a novel reproductive behaviour under the strong selection of predation pressure.Due to habitat fragmentation and habitat loss,we suggest setting up arch structures and provide small branches and leaves in degraded or fragmented habitats to improve their suitability for partridge reproduction.This method may contribute to increasing the reproductive success of Hainan Partridge and thus compensate for its continuous population decrease.
基金financed by the National Natural Science Foundation of China(Grant Nos.31601856 and 31670398)。
文摘Background:The Rufous-backed Bunting,Emberiza jankowskii,is an endangered species that is primarily distributed in Inner Mongolia,China.The main threats to the continued persistence of this species are habitat loss and degradation.However,the impact of population loss on genetic diversity remains unclear.To support future conservation and management efforts,we assessed the genetic diversity and population structure of E.jankowskii using mitochondrial DNA and microsatellites.Methods:Blood samples were collected from 7-8-day-old nestlings in Inner Mongolia,China between May and August of 2012 and 2013.Mitochondrial DNA sequences and microsatellite markers were used to assess the genetic diversity,genetic structure and inbreeding of E.jankowskii.The results of genetic diversity and inbreeding were compared to other avian species.Results:We found an unexpectedly high level of genetic diversity in terms of mitochondrial DNA and microsatellite compared to other avian species.However,there were high levels of gene flow and minimal genetic structuring,among the fragmented breeding populations of E.jankowskii in Inner Mongolia.These findings suggest that E.jankowskii in Inner Mongolia is a metapopulation.Despite the high genetic diversity of E.jankowskii,local populations in each small patch remain at risk of extinction due to habitat loss.In addition,the E.jankowskii population has a high risk of inbreeding.Conclusions:To minimize further loss of genetic diversity of this endangered species,we suggest that the E.jankowskii in Inner Mongolia should be considered as a protected species for management purposes.Conservation efforts should concentrate on E.jankowskii habitat management.This may be most effectively achieved by protecting the current breeding habitats and prohibiting over-grazing.
文摘Introduction:Deforestation significantly impacts large carnivores that depend on large tracts of interconnected forest habitat and that are sensitive to human activities.Understanding the relationship between habitat use and spatial distribution of such species across human modified landscapes is critical when planning effective conservation strategies.This study assessed the presence of potential landscape connectivity thresholds resulting from habitat fragmentation associated with different deforestation patterns using a scale-based approach that links species-specific home ranges with the extent of anthropogenic activities.The objectives were(1)to quantify the spatial and temporal distribution of natural vegetation for five common deforestation patterns and(2)to evaluate the connectivity associated with these patterns and the existence of potential thresholds affecting jaguar dispersal.The Bolivian lowlands,located within jaguar conservation units,were analysed with landscape metrics to capture the spatial and temporal changes within deforested areas and to determine potential impact on jaguar connectivity and connectivity thresholds for dispersal.Results:Over the period of 1976–2005,the amount of natural vegetation has decreased by more than 40%in all locations with the biggest changes occurring between 1991 and 2000.Landscape spatial structure around jaguar locations showed that jaguars used areas with mean proportion of natural areas=83.14%(SE=3.72%),mean patch density=1.16 patches/100 ha(SE=0.28 patches/100 ha),mean patch area=616.95 ha(SE=172.89 ha)and mean edge density=705.27 m/ha(SE=182.19 m/ha).We observed strong fragmentation processes in all study locations,which has resulted in the connectivity of jaguar habitat decreasing to<20%by 2005.A connectivity threshold zone was observed when the proportion of natural vegetation was less than 58.4%(SE=1.3).Conclusions:Assessing fragmentation and connectivity for carnivores within the extent of human-modified landscapes proved to be an effective way to understand the changes caused by deforestation and their potential effects on large carnivore habitats.Our study highlights the importance of scale-based approaches for assessing current conservation challenges to protect large carnivores.
文摘The giant panda faces severe threats from habitat fragmentation and isolation.Currently,giant panda populations have been fragmented into 30 habitat patches.The disappearance of isolated small populations and studies on the genetic diversity of various populations have shown that small isolated panda populations are at a high risk of dying out completely.Habitat fragmentation has seriously impaired the ability of the giant panda to resist climate changes and other natural disasters,such as large-scale,synchronous bamboo blooming.The Min Mountains have the largest population of pandas in China,numbering 581 individuals and accounting for 52%of the total(1114)in China.Geographic isolation means that giant pandas in the Min Mountains are divided into two populations(population A in the north and population B in the south).Population B,which had only 42 individuals in 1989,is severely threatened by high-density human populations and the loss of genetic diversity.However,we have identified an important corridor connecting the two populations.This paper explains the importance and the feasibility of reestablishing this corridor.Due to the special geographic locations of these two populations(two rivers block the migration of giant pandas between south and north),the corridor is the only passage for giant pandas in the region.Recent studies have also shown an increase of giant panda activity in the area of the corridor.However,vegetation in the corridor has been severely degraded.Bamboo forest must be restored in this area to provide food for the pandas during migration.The effects of human activities must be reduced in order to maintain panda habitat.We believe that a restored corridor will be of great benefit to the survival of giant pandas in the Min Mountains,especially for population B.Successful re-establishment of a corridor will be a valuable model for corridor construction in the future.
基金supported by RDA agenda research PJ01574604the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(Grant no.:NRF-018R1A6A1A03024).
文摘Background The topology of the plant-pollinator network can be explained by the species’abundance and their random interactions.Plant-pollinator networks can be studied in the context of a landscape,because each patch can accommodate a certain local network.Local populations of pollinators in the landscape can be connected through migration and then constitute a metanetwork that is known as a combination of spatial and ecological networks.In this regard,habitat fragmentation can affect the topology of plant-pollinator metanetworks through changes in the species abundance and limiting their interactions.However,it is not clear what pattern(fragmented or aggregated)of the landscape structure can accommodate networks with a higher degree of specialization.Methods we created simulated landscapes with different forest proportions scenarios(from 5%to 50%of the total landscape)and degrees of fragmentation.Then,for each landscape,we limited the proportion of pollinators to the forest patch.We assumed that plants and pollinators are randomly distributed around the landscape and interact randomly.We used landscape metrics to measure different aspects of landscape structure and bipartite metrics for calculating the degree of specialization in plant-pollinator networks.Results The statistical relationship between bipartite and landscape metrics showed that the relationship between the topology of plant-pollinator networks and the landscape structure is affected by the forest amount in the landscape and the degree of forest fragmentation.We also found that according to the nestedness and H2(a measure of specialization)metrics,fragmented landscapes contain more general plant-pollinator networks.Conclusions Our findings suggest that fragmented landscapes,characterized by scattered forest patches,can promote higher levels of interaction between limited pollinators and diverse flowers,leading to more general plant-pollinator networks.
基金supported by a scholarship to GNS from the Coordenacao de Aperfeicoamento de Pessoal de Nível Superior(CAPES)(Code 001)Fundacao de Amparoa Pesquisa do Estado de Minas Gerais(FAPEMIG APQ-00401-19).RMH received a Fulbright-Brasil Distinguished Scholar grantthe National Council for Scientific and Technological Development(CNPq)for research productivity fellowships(RL#312531/2021-4,LFAM#302406/2019-0).
文摘Riverscape connectivity is a critically important component determining the ecological condition of lotic ecosystems.We evaluated changes in fish assemblages caused by the loss of connectivity by mine tailings storage dams(TSDs),hypothesizing that headwater fish assemblages are restructured by TSDs located downstream,even though the upstream habitats are not altered.We used standard methods to collect fish in 24 first to third order sites,with half draining to TSDs(dammed)and the other half free from this impact(undammed).To identify differences between treatments,we used PERMANOVA to test both environmental variables and ichthyofauna composition(Bray-Curtis similarity index)and evaluated the biological metrics that most influenced assemblage composition change.As expected,we observed no difference between treatments for environmental variables,but we did observe differences in fish assemblage composition.We also observed five metrics with lower values in dammed streams(richness and abundance of intolerant species,siluriform richness,and abundance of Pareiorhaphis cf.proskynita and Trichomycterus brasiliensis)and two metrics with higher values in dammed streams(perciform richness and abundance of Oligosarcus argenteus).We believe these changes resulted from of stream fragmentation by TSDs,in addition to source-sink mechanisms and conclude that mine TSDs located downstream change headwater fish assemblages,an impact often neglected in biomonitoring and bioassessment studies.
