Effects of Habitat Fragmentation on Species Diversity of Animals and Plants

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.

Dynamics of additional food provided predator-prey system with habitat fragmentation

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.

The effects of habitat fragmentation on the reproduction and abundance of Angadenia berteroi

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.

Level of habitat fragmentation determines its non-linear relationships with plant species richness, frequency and density at desertified grasslands in Inner Mongolia, China

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.

The integration of climate change,spatial dynamics,and habitat fragmentation:A conceptual overview

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.

Habitat fragmentation, vole population fluctuations, and the ROMPA hypothesis: An experimental test using model landscapes

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.

Plant assemblage and diversity variation with human disturbances in coastal habitats of the western Arabian Gulf

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.

Habitat Loss,Uneven Distribution of Resources and Fragmented Landscapes—A Resource Based Model of the Patch Size Effect

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.

Breeding biology and novel reproductive behaviour in the Hainan Partridge(Arborophila ardens)

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.

High levels of genetic diversity and an absence of genetic structure among breeding populations of the endangered Rufous-backed Bunting in Inner Mongolia,China:implications for conservation

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.

Impact of deforestation on habitat connectivity thresholds for large carnivores in tropical forests

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.

Corridor connecting giant panda habitats from north to south in the Min Mountains, Sichuan, China

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.

Achievements and challenges of primate conservation in China

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.

Mine tailings storage dams modify upstream headwater fish assemblages

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.

Arthropods on plants in a fragmented Neotropical dry forest： A functional analysis of area loss and edge effects

Loss and fragmentation of natural ecosystems are widely recognized as the most important threats to biodiversity conservation, with Neotropical dry forests among the most endangered ecosystems. Area and edge effects are major factors in fragmented landscapes. Here, we examine area and edge effects and their interaction, on ensembles of arthropods associated to native vegetation in a fragmented Chaco Serrano forest. We analyzed family richness and community composition of herbivores, predators, and parasitoids on three native plant species in 12 fragments of varying size and at edge/interior positions. We also looked for indicator families by using Indicator Species Analysis. Loss of family richness with the reduction of forest fragment area was observed for the three functional groups, with sirnilar magnitude. Herbivores were richer at the edges without interaction between edge and area effects, whereas predators were not affected by edge/interior position and parasitoid richness showed an interaction between area and position, with a steeper area slope at the edges. Family composition of herbivore, predator, and parasitoid assemblages was also affected by forest area and/or edge/interior situation. We found three indicator families for large remnants and five for edges. Our results support the key role of forest area for conservation of arthropods taxonomic and functional diversity in a highly threatened region, and emphasize the need to understand the interactions between area and edge effects on such diversity.

Persistent pollutants and the patchiness of urban green areas as drivers of genetic richness in the epiphytic moss Leptodon smithii

We determined genetic variation and metal and polycyclic aromatic hydrocarbon concentrations in Leptodon smithii moss collected in holm oak stands at cities, outskirts and remote areas of Campania and Tuscany（Italy） to investigate if anthropogenic pressure（pollutant emissions and land use change） affects moss genetic richness. In both regions, metal and polycyclic aromatic hydrocarbon concentrations reflected the trend urban 〉 outskirts 〉 remote areas, excepting Tuscany remote site. In both regions,the moss gene diversity increased from urban to remote areas. The findings suggest the extent and the fragmentation of urban green areas, as drivers of moss genetic richness.

Plant growth in a fragmented forest is a consequence of top-down and bottom-up processes, but not their interaction

Aims Habitat loss and fragmentation are the leading causes of global biodiversity decline.How fragmentation(leading to edge effects,increased isolation and declining habitat size)interacts with top-down processes like vertebrate herbivory,an important driver of vegetation structure and composition in many ecosystems,is poorly quantified.Interactions between fragmentation and changes in her-bivory may exacerbate their individual influences on plant growth,with implications for management of native plant communities within fragmented landscapes.We examined the effects of habitat fragmentation on herbivore activity,and also how both fragmen-tation and mammalian herbivory influence growth of understorey plant species.Methods This study was conducted at the Wog Wog habitat fragmentation experiment,located in south-eastern New South Wales,Australia.We use herbivore exclusion plots across an experimentally frag-mented landscape to assess the interactive effects of fragmenta-tion and herbivory on the growth of four plant species that vary in growth form and rarity in the landscape.Important Findings We observed species-specific responses to both herbivory and fragmentation,but no additive or interactive effects between these drivers.We show that a reduction in herbivore activity within frag-ments does not correspond with an increase in plant growth,even for the most palatable species.Rather,top-down processes continue to operate across the fragmented landscape.Although changes in habitat conditions within fragments appear to negatively influence both plant growth and mammalian herbivore activity,it is likely that alterations to bottom-up effects(i.e.fragmentation)may be more important than top-down effects(i.e.herbivores)for the spe-cies under investigation.The species-specific response of plants to herbivory or fragmentation may have implications for temporal and spatial population persistence in fragmented landscapes and ulti-mately fragment vegetation structure.

Variation of a floral polymorphism at different spatial scales in the Mediterranean geophyte Narcissus assoanus

Aims Habitat fragmentation impacts the spatial extent and isolation of local populations and communities.Although the biological consequences of these impacts have been well studied at the site level,effects directly related to changes in the spatial configuration of populations in the landscape remain less clear.The objective of this study is to examine how changes in the spatial-scale configuration of populations are associated with variability in morph rations in the floral polymorphic Mediterranean geophyte Narcissus assoanus.Methods We performed a nested analysis of morph ratio variation at three spatial scales:a 50×50 km regional scale in SE France,in fourteen 1×1 km landscapes located in the same region,and within 12 spatially extensive population patches.We also quantified variation in the behaviour of pollinators in population patches of contrasting spatial configuration.Important FindingsAt a regional scale,morph ratios show a geographic pattern of increasing isoplethy(1:1 morph ratio)away from centres of human population development and in upland pastures.At the landscape scale,isoplethy of local population patches is more correlated with decreased isolation among patches than with patch size.Finally,within local isoplethic populations,small patches can show significantly biased morph ratios.In small isolated patches,pollinators perform shorter flight distances among consecutive flower visits than in spatially extensive patches.This study of variation in a genetic polymorphism at multiple spatial scales provides new insights into the scale-dependent effects of habitat fragmentation and the potential occurrence of metapopulation dynamics in natural plant populations.