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1.
大兴安岭北坡火后紫貂冬季生境适宜性与景观格局的恢复   总被引:5,自引:0,他引:5  
由自然和人为原因引起的生境丧失与生境破碎化已严重影响到野生动物的生存。大兴安岭北坡是国家一级保护动物紫貂(Martes zibellina)的主要分布区,1987年发生在这里的特大森林火灾造成了森林景观的严重破碎化,紫貂的生存面临极大的威胁。本文的研究目的是为了确定火灾13年后,紫貂冬季生境的恢复程度。首先根据紫貂对冬季生境的喜好,选取对其生存影响较大的生态因子,结合数字化林相图,利用地理信息系统软件ArcGIS编制火烧前后的生境适宜性类型图。然后选取相关的景观格局指标,对火烧前后的生境格局进行对比分析。结果显示,尽管火后采取了一系列的森林恢复措施,但紫貂冬季适宜生境仍有大幅度减少,特别是中等适宜生境类型减少最为明显。适宜生境破碎化加剧,隔离度增加。适宜生境斑块的形状趋于简单,软边界比重有所增加。以上结果表明,与火前相比,紫貂生境明显恶化,需要较长的时间恢复。  相似文献   

2.
A combination of technics was used to assess landscape variables associated with the presence of the globally vulnerable giant armadillo (Priodontes maximus) in its southernmost distribution in the Chaco region of Argentina. Between 2017 and 2019, 369 km of foot and vehicle transects were run to search and record indirect evidence of the species (burrows and feeding excavations) in areas with different level of protection, including two national parks, three provincial parks, and non-protected areas. Distance sampling was used to estimate density of excavations and effective strip width sampled to estimate the surveyed area. Resource selection functions (RSFs) were used to assess the variables associated to its presence by comparing locations of excavations with available habitat within surveyed areas. In these RSF models covariates that may affect habitat use and survival of giant armadillos were included: three categorical ones: soil type, vegetation cover (forests vs. grasslands), protection level (national park, provincial park, non-protected), and five continuous variables: distance to nearest river, distance to nearest national park, distance to closest protected area, distance to nearest transformed area, and distance to natural grasslands. Habitat use was modelled pooling together burrows and feeding excavations, and models were validated with a pool of records previously excluded from the analysis. A total of 104 records of burrows and 344 of feeding excavations were recorded. The probability of occurrence of giant armadillo excavations was much higher within forests, within or near protected areas, and increased with the distance to rivers, to transformed areas, and to grasslands. In the study area, only 10% of the landscape surveyed has good- to high-probability of occurrence of giant armadillos. The maintenance of large surfaces of native forests and the consolidation, improvement, and connectivity among protected areas seem to be essential for the long-term survival of the endangered giant armadillo in Argentina.  相似文献   

3.
姜广顺  李京芝 《兽类学报》2021,41(5):604-613
目前全球物种正以前所未有的速度灭绝,对野生动物栖息地开展有效的评估与科学的保护是阻止濒危物种走向灭绝,保持其可持续生存与发展的重要前提和手段。本文针对我国的食肉类、有蹄类、灵长类、小型兽类、海洋兽类5个类别的濒危兽类,综述了其栖息地评估与保护研究进展的现状和成果,对相关学术成果进行了归纳与分析,以期为栖息地的科学保护与管理梳理出系统、可供借鉴的研究方法和技术手段,并对其理论和技术的挑战进行了展望,提出了我国濒危兽类栖息地评估和保护研究应走向整体化、定量化、智能化,以及多学科交叉融合应用的“精准化”发展方向,为国家生态建设工程的有效实施提供重要技术支撑。  相似文献   

4.
Habitat quality is often evaluated based on food availability. However, ecological theory suggests cover should be a more important decision rule when food is not a proximate threat to fitness, as cover mediates predation risk as well as other important factors of fitness. In reality, vegetation characteristics related to food availability and cover are rarely coupled with animal use in the same space and time to determine their relative influences on habitat use. Using an array of 81 camera traps in a matrix of forest management strategies used to deliberately cause a wide disparity in vegetation characteristics, we monitored intensity of use by white-tailed deer (Odocoileus virginianus) and wild turkey (Meleagris gallopavo). We measured vegetation characteristics related to food and cover at each camera trap location then used a generalized additive model to determine how vegetation characteristics specific to the location affected intensity of habitat use by animals at the location. Consistent among both species, cover best explained intensity of habitat use. Contrastingly, food did not explain intensity of habitat use well for either species. Some vegetation simultaneously provides cover and food, and our data indicate that areas with vegetation characteristics providing both resources had the greatest influence on intensity of habitat use by both species. Our results suggest deer and turkey may perceive cover as a more important habitat component when food is not a proximate fitness threat.  相似文献   

5.
Temperate forests of southern South America are globally important because of their high level of endemism. I argue here that within southern South America, rainforests of the Chilean Coastal Range should be the primary target for new conservation efforts. Historically, most protected areas in southern South America have been designated to preserve forests above 600 m, mainly in the Andes. However, Coastal Range forests have higher species richness and are under greater threat than Andean forests at similar latitudes. Coastal forests are characterized by the presence of numerous narrow-range endemics, among them two monotypic plant families. The higher frequency of endemic species in Coastal Range forests is attributed to its more stable biogeographic history compared to the Andes, particularly during the glacial events of the Quaternary. Due to the extent of human impact, the remaining fragments of coastal forests are quite distant from one another, and are disconnected from the larger protected areas of Andean forests. Only 439000 ha of Valdivian coastal forest still remain, including some remnants of primary forest. New private or public reserves should be created to protect the last remnants of continuous forest remaining on the Coastal Range of the Valdivian region (40–42° S). A different conservation strategy should be applied north of 40° S, where protected areas are too small and fragments are too scattered to maintain viable populations of most vertebrates. In this latter area, I recommend expanding existing reserves, restoring native forests, and interconnecting remnant forests through a corridor network.  相似文献   

6.
Freshwater ecosystems are declining faster than their terrestrial and marine counterparts because of physical pressures on habitats. European legislation requires member states to achieve ecological targets through the effective management of freshwater habitats. Maps of habitats across river networks would help diagnose environmental problems and plan for the delivery of improvement work. Existing habitat mapping methods are generally time consuming, require experts and are expensive to implement. Surveys based on sampling are cheaper but provide patchy representations of habitat distribution. In this study, we present a method for mapping habitat indices across networks using semi-quantitative data and a geostatistical technique called regression kriging. The method consists of the derivation of habitat indices using multivariate statistical techniques that are regressed on map-based covariates such as altitude, slope and geology. Regression kriging combines the Generalised Least Squares (GLS) regression technique with a spatial analysis of model residuals. Predictions from the GLS model are ‘corrected’ using weighted averages of model residuals following an analysis of spatial correlation. The method was applied to channel substrate data from the River Habitat Survey in Great Britain. A Channel Substrate Index (CSI) was derived using Correspondence Analysis and predicted using regression kriging. The model explained 74% of the main sample variability and 64% in a test sample. The model was applied to the English and Welsh river network and a map of CSI was produced. The proposed approach demonstrates how existing national monitoring data and geostatistical techniques can be used to produce continuous maps of habitat indices at the national scale.  相似文献   

7.
Intraspecific microhabitat segregation is expected to arise when there are age- or sex-specific differences in predation risk. The degree to which conspecific predation (cannibalism) can generate this risk, however, is poorly understood. In this paper, we examine microhabitat use, cannibalism, and individual responses to the presence of conspecifics in Thermosphaeroma thermophilum, an endangered isopod crustacean species that is endemic to a single, thermal spring in Socorro, N.M. USA. In samples from the natural habitat, juveniles (mancas) were found mainly on vegetation, whereas adults were found predominantly on bottom sediments. Females were found on vegetation more often than males. In laboratory containers without refuges, males cannibalized females, males and females cannibalized mancas, and mancas cannibalized each other, even in the presence of alternative food. When placed in containers provided with refuges, mancas actively avoided adults. We suggest, therefore, that cannibalism in T. thermophilum generates age-, size-, and sex-specific predation risks which are responsible for microhabitat segregation between mancas and adults, and between males and females. Since interspecific predation in the spring is negligible, cannibalism appears to play a significant role in population regulation and behavioral evolution in this species. We recommend, given the current “endangered” status of this species, that microhabitat heterogeneity be maintained in its native spring because it provides refuges from cannibalism and may support a larger and more viable natural population. Received: 28 June 1996 / Accepted: 24 February 1997  相似文献   

8.
The generality of mechanisms affecting habitat choice and grazing in seagrass meadows was evaluated in a latitudinal comparison of seagrass grazers from the temperate (60°N) Baltic Sea and the subtropical (30°N) Gulf of Mexico. Using similar habitat choice experiment set-ups in Finland and the USA, the role of food type, habitat complexity and predation hazard on habitat choice of the isopods Idotea baltica (Pallas) and Erichsonella attenuata Harger were tested. When shelter was provided by both living and artificial seagrass, epiphytic food resources on artificial vegetation were clearly preferred by both species, although Idotea was attracted to epiphyte-free seagrass when no alternative food was present. When choosing between food and shelter, both species preferred epiphytic food over shelter. However, under predation hazard of fish, Erichsonella clearly switched to the habitat offering shelter, while the presence of a predatory fish produced no preference for shelter by Idotea. Food type may be considered as an universal mechanism that partly determines the presence of grazers in seagrass habitats and is, in the absence of a predator, more important than shelter. Predation risk affected the behaviour of the grazers, but the response varied between species possibly due to varying importance of fish predation in the areas studied. Received: 16 November 1998 / Accepted: 13 February 1999  相似文献   

9.
Papyrus Cyperus papyrus swamps are characteristic of many wetlands of tropical Africa. Like most wetland habitats worldwide, they are under human pressure due to harvesting and reclamation for agriculture. Changes in papyrus cover were assessed using aerial photographs at three Important Bird Areas (IBAs) in the Kenyan sector of Lake Victoria. Papyrus area losses of 50% (Dunga), 47% (Koguta) and 34% (Kusa) occurred between 1969 and 2000. The habitat loss and degradation at the sites appeared purposeful, driven by demand for agricultural land and other papyrus products. Cleared papyrus and cultivated areas around all sites increased over the same period. If papyrus habitat loss continues at current rates, papyrus swamps at Dunga and Koguta will disappear by 2020, and Kusa will be reduced to only 19% of its 1969 area. Human population growth around the sites, with concomitant increase in land use activities and papyrus harvesting are the major factors that account for papyrus area reductions. Loss of total habitat is accompanied by deterioration in habitat quality within remaining areas. Papyrus physical structure (height and density) inversely correlate to human disturbances that include footpaths, cutting, burning, grazing and farming. The continued papyrus habitat loss and degradation represents a significant threat to biodiversity conservation particularly for papyrus-specialist birds and other papyrus-reliant species in western Kenya. The observed pattern of papyrus extents and land use changes at all sites provide the site-scale information necessary for papyrus conservation planning. In particular, conservation action is needed most urgently at Dunga and Koguta as they face severe land use pressures.  相似文献   

10.
Synopsis Behavioral preference for a structured habitat (artificial seagrass) by juvenile walleye pollock,Theragra chalcogramma, was tested in controlled laboratory experiments. We monitored position of fish in 2000 1 tanks with and without artificial seagrass present in one half of the tank. In addition, we exposed walleye pollock to a predator model, assessing their response when a grass plot was available or unavailable as a potential refuge. In the absence of predators, the fish avoided the artificial seagrass, displaying a preference for the open water side of the experimental tanks. In the presence of a predator model, however, juvenile walleye pollock readily entered the artificial seagrass plots. In addition, they often remained in the grass canopy in proximity to the predator instead of moving out of the grass to avoid the predator (when no grass was present they consistently moved to the opposite side of the tank from the predator). The behavioral choices exhibited in this study suggest that juvenile walleye pollock modify habitat selection in response to perceived predation risk, and recognize the structure provided by artificial seagrass as a potential refuge.  相似文献   

11.
Lahontan cutthroat trout, Oncorhynchus clarki henshawi, are currently limited in their distribution to a patchwork of small isolated populations, the result of habitat degradation and natural variation in landscape and in-stream conditions. The objectives of this study were to determine if landscape topography influences trout distribution, and if water temperatures control this response. The work was carried out in a sub-basin of the Quinn River system, McDermitt Creek, which drains the sagebrush desert of southeastern Oregon and northern Nevada. Headwater tributaries of this creek consist of alternating canyon-confined and valley bounded reaches. Trout within these systems are challenged by low discharge and high temperatures during the summer, and anchor ice during the winter. Contiguous whole stream surveys were used to look at trout distribution during the summer of 2003 and spring and fall of 2004. Our results suggested that topography can affect trout distribution. Trout numbers were highest in areas with greater numbers of nick-points (the transition zones between less confined and more confined valley segments) and greater valley confinement. Additionally, in the downstream portion of our headwater reaches, more trout were found in nick-points than expected based on the availability of this habitat type. Our data suggest that hyporheic inputs may be high in such areas, thus providing trout with shelter from warm water in the summer, anchor ice in the winter, and shallow stream depths during all seasons. Spatial occurrence of these areas of refugia can be taken into consideration when planning land use activities and restoration efforts. Further research is required to confirm that topography can affect the distribution of Lahontan cutthroat trout in other systems, and to better understand the mechanisms behind these patterns.  相似文献   

12.
Habitat size, habitat isolation and habitat quality are regarded as the main determinants of butterfly occurrence in fragmented landscapes. To analyze the relationship between the occurrence of the butterfly Cupido minimus and these factors, patch occupancy of the immature stages in patches of its host plant Anthyllis vulneraria was studied in the nature reserve Hohe Wann in Bavaria (Germany). In 2001 and 2002, 82 A. vulneraria patches were surveyed for the presence of C. minimus larvae. The occurrence was largely affected by the size of the food plant patches. In a habitat model that uses multiple logistic regression, the type of management and habitat connectivity are further determinants of species distribution. Internal and temporal validation demonstrate the stability and robustness of the developed habitat models. Additionally, it was proved that the colonization rate of C. minimus was significantly influenced by the distance to the next occupied Anthyllis patch. Concerning long-term survival of (meta-) populations in fragmented landscapes, the results show that lower habitat quality may be compensated by higher connectivity between host plant patches. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

13.
Zhou J  Chen B  Yu W W  Huang H 《农业工程》2011,31(5):264-270
Coastal wetland is located in the active interface between land and sea, which is one of the richest biodiversity habitats, while it is seriously disturbed and destroyed by anthropogenic activities in both terrestrial and marine parts. Habitat serves as the basis for organism survival, providing food, shelter, water, space and so on, and habitat degradation and loss caused by intense anthropogenic activities is widely considered as the main reason for biodiversity decline and loss. However, there is still limited study on the evaluating methods of coastal wetland habitats, especially for those in a large scale. In this study, methods for evaluating coastal wetland habitat quality, including selecting indicators, setting value assignment criteria and weights were discussed systematically, a method of coastal wetland habitat quality evaluation was established, and the habitat quality in Quanzhou Bay was also evaluated as a case study. The present study provided a new concept and method to assess quantitatively habitat status, indicate the ecological status and its change, and also reflect and predict indirectly the ecological impact of human activities.
Referring to the habitat evaluation system (HES) developed by United States in the mid 1970s, the evaluation method was established by thorough analysis of the characteristics of coastal wetland. The habitat indicators were selected in terms of three habitat factors as follows: chemical factors, including dissolved oxygen (DO), phosphate in seawater, sulfide in sediment, and regional priority pollutants; physical factors, including landscape naturalness index and coastline artificialization index; biological factors, including invasive species risk and area ratio of invasive alien species. Weights were established by Analytic Hierarchy Process, combined with several-round expert evaluation. Evaluation criteria providing principles for value assignment of each indicator, were established referring to previous standards and related researches. The final result for assessing habitat quality was indicated and stated by the value of Habitat Quality Index (HQI), which is the weighted sum of each indicator. Habitat quality increased with the HQI value, with value ranging from 0 to 100.
The established evaluating method was applied to assess the habitat quality of Quanzhou Bay, located in the southeast coastal zone of Fujian Province, with a total area of 136.4 km2, which is an important bay in Fujian. Quanzhou Bay wetland is a typical coastal wetland with diverse wetland habitats, including mangrove, estuary, island, aquaculture ponds, salt pan, shallow sea, mud flat and so on. The Quanzhou Bay is now seriously suffering environmental problems, e.g. eutrophication due to great discharge of domestic, agricultural and industrial wastewater, rapid urbanization and reclamation resulting in decreased wetland area, and the invasion of alien species. The evaluation results showed that the habitat quality index value was 68.13, 57.99 and 51.23 in 1989, 2002 and 2008, respectively, indicating that the habitat degraded gradually. The five major factors that led to decline of HQI value were phosphate in seawater, lead in sediment, landscape naturalness index and coastline artificialization index and area ratio of invasive alien species. Therefore, in order to improve and maintain habitat quality, it is urgent to control pollution, large-scale reclamation and Spartina invasion in Quzhou Bay.  相似文献   

14.
15.
新疆准噶尔盆地东部波斑鸨秋季栖息地选择   总被引:6,自引:0,他引:6  
2000年9月,利用粪便示踪和野外直接观察法对准噶尔盆地东部波斑鸨(Chlamydotis undulata)秋季栖息地进行了采样调查。结果表明:波斑鸨秋季栖息地地热平坦,视野开阔,广泛分布旱生和盐生荒膜植物,植被稀疏、低矮,并镶嵌有相对较高的灌丛块;影响波斑鸨秋季栖息地选择的环境因子是植被密度、物种丰富度和物候;秋季栖息地内的植被密度、草木植物种数、叉毛蓬密度、结实植物密度和物种数都极显著高于对照地内的相应成分;生长植物密度显著高于对照地;而假木贼密度和琵琶柴密度显著低于对照地。  相似文献   

16.
Srivastava DS 《Oecologia》2006,149(3):493-504
Although previous studies have shown that ecosystem functions are affected by either trophic structure or habitat structure, there has been little consideration of their combined effects. Such interactions may be particularly important in systems where habitat and trophic structure covary. I use the aquatic insects in bromeliads to examine the combined effects of trophic structure and habitat structure on a key ecosystem function: detrital processing. In Costa Rican bromeliads, trophic structure naturally covaries with both habitat complexity and habitat size, precluding any observational analysis of interactions between factors. I therefore designed mesocosms that allowed each factor to be manipulated separately. Increases in mesocosm complexity reduced predator (damselfly larva) efficiency, resulting in high detritivore abundances, indirectly increasing detrital processing rates. However, increased complexity also directly reduced the per capita foraging efficiency of the detritivores. Over short time periods, these trends effectively cancelled each other out in terms of detrital processing. Over longer time periods, more complex patterns emerged. Increases in mesocosm size also reduced both predator efficiency and detritivore efficiency, leading to no net effect on detrital processing. In many systems, ecosystem functions may be impacted by strong interactions between trophic structure and habitat structure, cautioning against examining either effect in isolation.  相似文献   

17.
Coastal wetland is located in the active interface between land and sea, which is one of the richest biodiversity habitats, while it is seriously disturbed and destroyed by anthropogenic activities in both terrestrial and marine parts. Habitat serves as the basis for organism survival, providing food, shelter, water, space and so on, and habitat degradation and loss caused by intense anthropogenic activities is widely considered as the main reason for biodiversity decline and loss. However, there is still limited study on the evaluating methods of coastal wetland habitats, especially for those in a large scale. In this study, methods for evaluating coastal wetland habitat quality, including selecting indicators, setting value assignment criteria and weights were discussed systematically, a method of coastal wetland habitat quality evaluation was established, and the habitat quality in Quanzhou Bay was also evaluated as a case study. The present study provided a new concept and method to assess quantitatively habitat status, indicate the ecological status and its change, and also reflect and predict indirectly the ecological impact of human activities.Referring to the habitat evaluation system (HES) developed by United States in the mid 1970s, the evaluation method was established by thorough analysis of the characteristics of coastal wetland. The habitat indicators were selected in terms of three habitat factors as follows: chemical factors, including dissolved oxygen (DO), phosphate in seawater, sulfide in sediment, and regional priority pollutants; physical factors, including landscape naturalness index and coastline artificialization index; biological factors, including invasive species risk and area ratio of invasive alien species. Weights were established by Analytic Hierarchy Process, combined with several-round expert evaluation. Evaluation criteria providing principles for value assignment of each indicator, were established referring to previous standards and related researches. The final result for assessing habitat quality was indicated and stated by the value of Habitat Quality Index (HQI), which is the weighted sum of each indicator. Habitat quality increased with the HQI value, with value ranging from 0 to 100.The established evaluating method was applied to assess the habitat quality of Quanzhou Bay, located in the southeast coastal zone of Fujian Province, with a total area of 136.4 km2, which is an important bay in Fujian. Quanzhou Bay wetland is a typical coastal wetland with diverse wetland habitats, including mangrove, estuary, island, aquaculture ponds, salt pan, shallow sea, mud flat and so on. The Quanzhou Bay is now seriously suffering environmental problems, e.g. eutrophication due to great discharge of domestic, agricultural and industrial wastewater, rapid urbanization and reclamation resulting in decreased wetland area, and the invasion of alien species. The evaluation results showed that the habitat quality index value was 68.13, 57.99 and 51.23 in 1989, 2002 and 2008, respectively, indicating that the habitat degraded gradually. The five major factors that led to decline of HQI value were phosphate in seawater, lead in sediment, landscape naturalness index and coastline artificialization index and area ratio of invasive alien species. Therefore, in order to improve and maintain habitat quality, it is urgent to control pollution, large-scale reclamation and Spartina invasion in Quzhou Bay.  相似文献   

18.
We examined the peripheral olfactory organ in newly metamorphosed coral-dwelling gobies, Paragobiodon xanthosomus (SL=5.8mm+/-0.8mm, N=15), by the aid of electron microscopy (scanning and transmission) and light microscopy. Two bilateral olfactory placodes were present in each fish. They were oval-shaped and located medio-ventrally, one in each of the olfactory chambers. Each placode had a continuous cover of cilia. The placode epithelium contained three different types of olfactory receptor neurons: ciliated, microvillous and crypt cells. The latter type was rare. Following a pelagic larval phase, P. xanthosomus settle to the reef and form an obligate association with one species of coral, Seriatopora hystrix. Their well-developed olfactory organs likely enable larvae of P. xanthosomus to detect chemical cues that assist in navigating towards and selecting appropriate coral habitat at settlement. Our findings support past studies showing that the peripheral olfactory organ develops early in coral reef fishes.  相似文献   

19.
Although the evolutionary interplay between gene flow and local adaptation of organisms in heterogeneous environments has been widely discussed from a theoretical point of view, few empirical studies have been designed to test predictions on the consequences of habitat patchiness on the evolution of life history traits. Using blue tits in Mediterranean habitat mosaics as a model, we defined two nested levels of habitat heterogeneity: an inter-regional level which compares two isolated landscapes (mainland, southern France vs the island of Corsica), and an intra-regional level which compares two habitat types within each landscape (deciduous vs evergreen trees). Deciduous habitats are more common than evergreen habitats on the mainland whereas the opposite is true on the island. Results suggest that: (1) on a regional scale, each population is specialized to the more common habitat, i.e. life history traits have evolved in such a way that breeding success is high; (2) in the less common habitats within each landscape, birds are clearly mistimed because they mismatch the best period of food availability, and hence their breeding success is lower; and (3) the density of the populations and the morphometry of the birds support the model of ideal despotic distribution. These results, which are supported by preliminary data on the genetic variation and gene flow of populations in the mainland landscape, are consistent with a source-sink model of population structure within each landscape. They are discussed in the framework of metapopulation theory and habitat selection models.  相似文献   

20.
Identifying potential refugial habitats in the face of rapid environmental change is a challenge faced by scientists and nature conservation managers. Relict populations and refugial habitats are the model objects in those studies. Based on the example of Actaea europaea from Central Poland, we analyse the habitat factors influencing relict populations of continental, light-demanding species in lowland forests and examine which habitats of studied species corresponding most closely to ancient vegetation. Our results indicate that the current refugial habitats of Actaea europaea include not only communities which are very similar to ancient open forest but also forests with a closed canopy. Although the populations are influenced by nitrogen and light availability, the co-occurrence of these two factors in forest communities is limited by dense canopy formation by hornbeam and beech trees on fertile soils and in more humid conditions. Our findings indicate that the future survival of relict, light-demanding communities in lowland forests requires low-intensity disturbances to be performed in tree-stands, according to techniques, which imitate traditional forests management.  相似文献   

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