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.

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.

β-diversity Patterns of Plant Community in Fragmented Habitat in a Degenerated Meadow in Songnen Plain,China

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 of β-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,turnovers 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 of β-diversity patterns of plant community.

Behavioral fragmentation of waterfowl habitat and its landscape ecological design in Shuangtai-hekou Reserve,Liaoning,China

Behavioral fragmentation of wildlife habitat is discussed. Using “buffer” module in ARC/INFO, behavioral fragmentation habitat of Red crowned crane, Saunders gull, Oriental white stork and Siberian white crane was calculated in the Shuangtai hekou National Reserve, Liaoning Province, China. The result showed that breeding Red crowned crane, Siberian white crane and breeding Saunders gull are very sensitive to fragmentation factors. Suitable habitat is so little for more than 2000 Saunders gull to breed. The reserve only has a capacity of 38 pairs for breeding Red crowed crane. Two key measures were made. First, dismantles all the abandoned oil wells and recovers the original ecosystem to decrease the fragmentation effect, directly benefit to breeding or migration of Red crowned crane and Oriental white stork. Second, recovers the Suaeda tidal mud flat from artificial shrimp and crab pond in the kernel zone of the reserve to enlarge the habitat area of Saunders gull and Siberian white crane.

Genetic Variation in <i>Salamandra</i><i>infraimmaculata</i>from Different Habitats Using Amplified Fragment Length Polymorphism

The purpose of the present study was to examine the genetic variation in Salamandra infraimmaculata from different breeding site habitats using the Amplified Fragment Length Polymorphism (AFLP) method. The results of the dendogram from a hierarchical cluster analysis show that the grouping of S. infraimmaculata as cluster 5 differs from all the other clusters, including the St1 (Tel-Dan stream) population, which was the most predictable. Five Haplogroups (Hg) were characterized. The mean number of alleles per locus in each population (Ne) ranged from 10.566 (Sp1) to 2.720 (Po6). An average estimated heterozygosity (He) by population ranged from 0.100 (Po6) to 0.186 (St1). Population St1, a permanent breeding site where water was available all year round, exhibited the highest level of polymorphism, while population Po6, from the ephemeral breeding site, exhibited the lowest level of polymorphism. Gene flow between clusters showed that clusters 3 and 4 are sources of migrants and also receive gene flow, while clusters 1 and 2 may be a source of migrants but may not receive much gene flow. A phylogenetic analysis, based on clustering using Nei’s genetic distance, demonstrated that the Tel-Dan population is located on a separate branch within its sub-population. The conclusion of the present study shows that the genetic divergence among isolated populations is not correlated to distance but is affected by the variation of habitats.

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.

滇东南南溪河中下游懒猴种群分布与保护现状

蜂猴(Nycticebus bengalensis)与倭蜂猴(Xanthonycticebus intermedius)是国内现存的两种懒猴科灵长类,因其独特的生态及行为特点,具有重要的研究与保护价值。由于受到捕猎及栖息地丧失的持续威胁,懒猴种群持续下降,分布区日益缩减,但种群及分布调查的缺失阻碍了保护计划的制定与实施。滇东南是历史记载中懒猴分布的重要区域,并且是潜在的两个物种的同域分布范围。2022年10月至2023年9月,通过访问、网络及样线调查相结合的方式,对滇东南范围内河口和马关县辖区的懒猴种群分布及保护现状进行了详细评估,确定了9个懒猴集中分布点。结果表明,本区域仍是国内懒猴分布的重要范围,且是倭蜂猴分布最为集中的区域之一。当地民众对懒猴的认知尚处于较低水平,受教育程度、年龄及经济状况的显著影响。懒猴分布区域多位于保护区边缘,当前的保护措施缺乏针对性,需要加强监测管理,建设生态廊道并通过宣传教育提升当地民众意识。

生境面积大小对Janzen-Connell效应中密度和距离制约的影响

为探究生境面积大小对Janzen-Connell (JC)效应中密度和距离制约的影响以及驱动机制,为生境破碎化背景下植物多样性的维持机制提供科学依据,本研究在Web of Science数据库中收集并筛选出1970-2019年全球50个森林地点作为数据基础,采用荟萃分析法分析密度和距离制约实验中不同类型驱动者的效应值大小,并采用分段回归和非分段回归分别模拟分析密度和距离制约效应值与生境面积的关系。结果表明,在67项研究的161项实验中,病原菌和无脊椎动物的效应值大小在距离制约实验中显著小于0(存在JC效应),而在密度制约实验中不显著。相反地,脊椎动物的效应值大小仅在密度制约实验中显著小于0。虽然只有距离制约效应值随生境面积的减少呈先增大后减小的趋势,但密度制约趋势线的拟合转折点在距离制约之前,表明生境面积减少会先影响密度制约。本研究阐明了密度和距离制约的主要驱动者分别是密度型驱动者(脊椎动物)和距离型驱动者(病原菌和无脊椎动物),而密度制约比距离制约对生境面积的减少有更为敏感的表现,可能是这两种驱动者对生境面积的需求不同所导致的。因此,在不同生境面积的片段中关注不同类型的驱动者有利于生物多样性的维持。

乌伦古河流域中下游蒙新河狸生境破碎化评价

在对新疆乌伦古河流域中下游栖息的蒙新河狸Castor fiber birulai生境实地调查的基础上,利用景观格局指数、景观连接度和MaxEnt模型研究其生境破碎化现状,为该物种及其生境的保护和管理提供参考。结果表明:2000—2020年研究区域景观格局变化主要表现为耕地、建设用地和裸地的斑块面积增加,草地、林地和湿地的减少;蒙新河狸适宜生境面积分布狭窄,仅占总面积的12%(386.92 km^(2));适宜蒙新河狸分布的主要环境变量组成特征为最冷月份最低温度(-26.43~-23.07℃)、最暖季度平均温度(20.31~21.78℃)、最干季度降水量(20.04~25.72 mm)、土壤酸碱度(7.72~8.01)、土壤有机碳含量(1.2%~2.6%),以及有草地、林地和水体分布的土地利用类型;不同扩散距离下蒙新河狸适宜生境的景观连接度普遍较低。建议在乌伦古河流域中下游建立蒙新河狸生境廊道,增加斑块间的连通性,改善蒙新河狸的生境。

生境破碎化过程对流域生境质量的影响

近几十年来,随着工业化、城市化的加速推进,人类活动对自然生境的干扰越来越频繁,导致生境破碎化与生境质量下降。在流域尺度上科学模拟生境破碎化过程及其对生境质量的影响,对于提升生物多样性和生态系统功能具有重要意义。以鄱阳湖流域为研究区域,基于InVEST模型分析区域生境质量的演变特征;从生境面积、生境边缘和生境隔离三个特征维度模拟生境破碎化过程;采用广义加性模型和地理探测器探究不同生境破碎化过程对生境质量变化的影响与交互作用。研究结果表明:(1)鄱阳湖流域生境质量呈下降趋势,从2000年的0.7862下降到2010年的0.7807,再下降到2020年的0.7715,但总体生境质量较好。生境质量较优的区域主要分布在流域南部、东北部以及西部地区,生境质量较差的区域主要分布在各个子流域的交界处。(2)2000—2010年,鄱阳湖流域生境面积占比下降、生境边缘增加和生境隔离增加三个生境破碎化过程分别占总研究区网格数的34.70%、30.15%和4.50%;2010—2020年分别占总研究区网格数的34.80%、30.69%和4.40%;2000—2020年分别占总研究区网格数的40.82%、37.50%和5.46%。生境面积减少的网格主要集中在鄱阳湖流域的中北部地区;生境边缘增加的网格分布和生境面积减少的网格分布相似;相比之下,生境隔离增加的网格较少,主要分布在各城市的中心城区范围。(3)生境破碎化过程对生境质量具有显著影响,两者呈非线性负相关关系;三个生境破碎化过程两两之间交互作用对生境质量的影响呈现双因子增强趋势。研究结果可为鄱阳湖流域生态格局优化与生境质量提升提供科学参考。

新建天水至陇南铁路建设期对沿线野生兽类的影响

为准确了解穿越新建的秦岭山区天水至陇南铁路对野生动物分布、生活等造成的影响,给工程施工管理和野生动物保护提供依据,分别于开工前(2021年)和建设期(2023年)对沿线60个主要施工点及其周边的野生兽类开展调查。结果显示:开工前发现兽类21种,建设期发现18种,且建设期野生兽类实体或痕迹遇见频率比开工前全面下降;不同施工类型对野生兽类的影响显著不同,隧道出入口、斜井口等施工类型对野生兽类影响最大,弃渣场、新建施工便道影响中等,拌和站、污水处理站、路基等几乎无影响。林麝和毛冠鹿对铁路施工的反应最为敏感,黄喉貂次之,中华斑羚、中华鬣羚等国家重点保护野生动物的遇见频率也显著下降。建议持续开展施工区域重点位置野生动物监测,及时了解铁路建设对野生动物的影响,以提出科学合理的补救措施,缓解工程对沿线野生动物的影响。

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.

Post-fire habitat restoration of sables during winter season in northern slope of the Great Xing＇an Mountains

Habitat loss and fragmentation have been associated with the decline of endangered species. In 1987, a catastrophic fire in the northern Great Hing＇an Mountains of China, where the main habitat of sables （Martes zibellina） is located, aggravated the loss and fragmentation of the forest landscape. Due to restricted distribution and low population density, sables were listed in the national first-grade protected species in China. The objective of this paper was to identify to what extent the habitat of sables had been restored 13 years after the fire. Based on the behavioral data, which came from field survey information by radio-tracking, GPS （Global Positioning System） and forest inventory data, suitability habitat maps were derived using the Ecological Niche Suitability Model （ENSM）. In addition, the habitat structure was analyzed with selected landscape indices. Although forest cover mostly had been restored by 2000, the results indicated that, compared to the pre-fire situation, the areas of suitable habitat had been reduced significantly, especially those of less suitable, marginally suitable and moderately suitable designation. Fragmentation was aggravated, and suitable patches were found to be further isolated with the exception of those in most suitable areas. The ratio of the patch perimeter to area in unsuitable, moderately suitable and suitable areas decreased, while the ratios within other suitability types increased. Moreover, the percentage of soft boundaries decreased slightly, which can influence the redistribution of sables. The results above indicated that the suitable habitat had deteriorated, and the restoration of the sables＇ habitat remained to be done.

水位骤降下近岸栖息地和底栖动物变化特征

本研究于2014年秋对牡丹江中游段两处受电站调峰影响的河段进行野外调查,对6个岸边退水潭进行水质采样和大型底栖动物采集,分析其水质特征和底栖动物群落组成,与相邻天然主河道的栖息地环境因子和底栖动物群落结构进行对比,并通过冗余分析(RDA)研究退水潭中底栖动物分布与主要栖息地环境因子之间的关系。研究表明,退水潭与主河道的水质和底栖动物组成均有显著差异,退水潭处溶解氧含量和pH值显著高于临近河道,氨氮和总氮含量较高。双翅目、半翅目和腹足纲为退水潭中的优势底栖物种,退水潭中底栖动物物种丰度、生物密度、Shannon-Wiener指数和Margalef丰富度均较河道处低。冗余分析表明退水潭中影响底栖动物群落结构的关键环境因子为溶解氧、pH值、总磷等。

基于源地-廊道法的生态网络构建研究进展

构建生态网络是应对生境破碎化、恢复生物多样性和维持生态系统健康的重要手段。生态网络构建方法较为多样且各具特色,但往往优缺点并存,对实践应用产生困扰。文章首先对生态网络研究发展历程及其构建方法进行系统梳理;然后以基于“源地-廊道”法的生态网络构建为核心,分析生态网络结构识别要点、廊道提取方法,以及网络连接度评价方法;最后提出研究展望,以期为景观生态规划设计及其相关生态网络构建提供参考。