Distribution Patterns Of Species Richness Research Articles

Climate stability is more important than water-energy variables in shaping the elevational variation in species richness.

Changes in climate variables have an important impact on the prediction and protection of elevational biodiversity. Gaps exist in our understanding of the elevational distribution patterns in seed plant species richness. Our study examines the importance of climate variables in shaping the elevational variation in species richness. The importance of boundary constraint was also taken into account. Model selection based on Akaike's information criterion was used to select the best explaining climate models. Variation partitioning was used to assess the independent and joint effects of water–energy, physiological tolerance, and environmental stability variables on species richness. Our results revealed that: (a) Both raw (boundary constraint unreduced) and estimated (boundary constraint reduced) species richness showed large elevational variation, with the peak species richness seen at midelevations. The environmental variables were better at explaining the distribution pattern of species richness along the elevation, when the effect of boundary constraint was reduced; (b) the physiological tolerance and environmental stability variables explained more variation in raw and estimated species richness compared with the water–energy variables. Estimated species richness was better explained (98.6%) by the environmental variables than raw species richness (94%); (c) the water‐related variables generally had the highest independent effect on raw and estimated species richness and were dominant in shaping the elevational variation in species richness. Our findings quantify the influence of boundary constraint on the distribution pattern of species along an altitudinal gradient and compare the relative contributions of environmental stability and water–energy in explaining the altitude gradient distribution pattern of plant seed species.

Spatial variation of plant species richness in a sand dune field of northeastern Inner Mongolia, China

Species richness is an important indicator of species diversity. Different sampling intensities will very likely produce different species richness values. Substantial efforts have already been made to explicitly quantify the spatial variability of soil properties in different ecosystems. However, concerns still remain on how to characterize the effect of different sampling intensities on plant species richness within a given region. This study characterized the spatial variability of plant species richness and the species distribution pattern in a 25-hm2 sand dune plot in northeastern Inner Mongolia, China by using an intense sampling method (n=10,000). We also evaluated the overall effect of information loss associated with the spatial variability and distribution patterns of species richness under various scenarios of sampling intensities (n=10,000 to 289). Our results showed that semi-variograms of species richness were best described by the spherical and exponential models. As indicated by the nugget/sill ratio, species richness was different in terms of the strength of the spatial relationship. The different spatial metrics of species richness with increasing sampling intensities can represent different responses of the spatial patterns when compared with the reference set (n=10,000). This study indicated that an appropriate sampling intensity should be taken into account in field samplings for evaluating species biodiversity properly. A sampling intensity of n>2,500 for species richness yielded satisfactory results to resemble the spatial pattern of the above-quantified reference set (n=10,000) in this sand dune region of China.

Scale-dependent spatial patterns of species diversity in the tropical montane rain forest in Jianfengling, Hainan Island, China

Aims Spatial distribution patterns and formation mechanisms of species diversity are fundamental issues in community ecology. The objectives of this study are to assess the species diversity patterns at the different spatial scales in Jianfengling, Hainan Island, China. Methods Based on the dataset from the 60 hm plot in the tropical montane rain forest in Jianfengling, Hainan Island, the spatial distribution patterns of species richness, species abundance, Shannon-Wiener, Simpson and Pielou’s evenness indices were analyzed at six spatial scales, including 5 m × 5 m, 10 m × 10 m, 20 m × 20 m, 40 m × 40 m, 100 m × 100 m, and 200 m × 200 m, respectively. Important findings Results showed that spatial distribution patterns of species richness, species abundance and Shannon-Wiener index were much more obviously changed with the spatial scales than Simpson and Pielou’s evenness indices. Change of variance of the species richness with the increase of spatial scales was unimodal, which had the maximum value at the 20 m × 20 m scale. Variance of the species abundance showed a linear relationship with the increase of spatial scales. The positive relationship between species richness and abundance gradually decreased and even disappeared with the increase of sampling scales, which may be correlated with the increase of habitat heterogeneity. The effects of spatial scales on Shannon-Wiener, Simpson, and Pielou’s evenness indices may be also correlated with the composition of rare species in the plot.

秦岭重点保护植物丰富度空间格局与热点地区

PDF HTML阅读 XML下载 导出引用 引用提醒 秦岭重点保护植物丰富度空间格局与热点地区 DOI: 10.5846/stxb201311082697 作者: 作者单位: 山西大学环境与资源学院,山西大学环境与资源学院,中国环境科学研究院,中国环境科学研究院,中国环境科学研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学青年基金项目（31100392）；环保公益性行业科研专项（201209028） Spatial distribution patterns of species richness and hotspots of protected plants in Qinling Mountain Author: Affiliation: College of Environmental Science and Resources, Shanxi University,College of Environmental Science and Resources, Shanxi University,Chinese Research Academy of Environmental Sciences,Chinese Research Academy of Environmental Sciences,Chinese Research Academy of Environmental Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:秦岭地区物种资源丰富，是我国重要的生物多样性热点地区之一。以秦岭山系涉及的43个行政县为研究区域，基于重点保护植物的县级分布，并结合垂直分布和生境类型信息获得物种分布区范围，探讨重点保护植物的丰富度空间格局和热点地区。研究结果表明：该地区共包括重点保护植物200种，其中国家一级保护植物20种，国家二级保护植物180种；秦岭重点保护植物丰富度空间格局总体随山体呈东西向递减的条带状分布，东段随着山岭与盆地相间的地形呈扫帚状展开，南坡物种丰富度高于北坡；通过丰富度空间格局确定了3个热点地区，分别是：（1）伏牛-熊耳山地；（2）太白-佛坪山地；（3）天水东南部山地。将热点地区与国家级自然保护区叠加后鉴别出保护空缺地，可为下一步实施科学的生物多样性保护规划提供基础资料。 Abstract:Qinling Mountain with abundant species resources, was considered as one of the most important biodiversity hotspots in China. In this research, 43 administrative counties in Qinling Mountain were chosen as the study areas. Based on distribution of protected plants on the county level, and the species distribution range obtained from the database on vertical distribution and habitat types of the wild plants, spatial distribution patterns of species richness and hotspots of plants under state protection were studied. The results showed that: (1) there are 200 state protected plants in Qinling Mountain, among which 20 species were under category Ⅰ and 180 species were under category Ⅱ; (2) the overall distribution pattern of species richness is a zonal distribution along the mountain decreasing from east to west of the mountain and unfolding with a broom shape between the mountains and basins in the east of Qinling Mountain. Furthermore, the species richness in the south slope is much higher than that in the north slope; (3) three hotspots were identified by the spatial distribution patterns of species richness, including Funiu-Xiong'er mountainous region, Taibai-Foping mountainous region and the southeastern mountainous region of Tianshui. The conservation gap can be identified by overlaying the hotpots and the distribution of national nature reserve. Results of this study would provide important basic information for the further scientific biodiversity protection in Qinling Area. 参考文献 相似文献 引证文献

Contribution of rarity and commonness to patterns of species richness in biogeographic transitions regions: Woody plants of Uruguay

There is a growing body of evidence suggesting that widespread (i.e. common) rather than geographically restricted species (i.e. rare) shape the overall distribution patterns of species richness. This is a non-intuitive fact, given that local and regional assemblages are normally composed by numerous rare species and few common ones. We evaluated here the primacy of common species in a biogeographic transition zone, where rarity has frequently a higher incidence. We analysed the geographical variability of trees and shrubs in Uruguay, located in a transitional zone between prairie and forest biomes, to assess the relative contribution of rare and common species to the generation of richness patterns. The distribution of 301 species of the native woody assemblage of Uruguay was mapped over the national grid system (302 quadrants of approximately 22 × 30 km), using published data and herbarium records. The overall assemblage was segregated into four subassemblages in function of species distribution (quartiles). Species richness in the four quartiles was positively correlated with overall richness, but common species (quartile 3) showed the highest level of correlation. Then, we ranked species from the most widespread to the most restricted (common-to-rare) and from the most restricted to the most widespread (rare-to-common). Along each stage of the sequences we obtained a series of species richness patterns for increasing numbers of species. Correlating the species richness pattern for each subassemblage of both sequences with that of the full assemblage, we also found higher correlations in the common-to-rare sequence. We conclude the Uruguayan woody plants assemblage has a very large number of rare species as expected for a transitional biogeographical zone, but it was the common species that contributed most to the overall pattern of species richness. We propose the low contribution of rare species is explained by the most interspecific variability in ecological determinants within the assemblage of rare species. Therefore the spatial covariance among rare species is low, and so is the relationship with overall species richness.

Set-aside fields in agri-environment schemes can replace the market-driven abolishment of fallows

Economic pressures from increased commodity prices and the growing demand for land for biomass plantations led to the abolition of compulsory set-aside fields in the European Union in 2008, affecting ca. 10% of total agricultural area. This area is now managed more intensively, and this is expected to adversely affect farmland biodiversity. Unfortunately, no mitigation of set-aside loss was introduced. Here we examined, whether or not set-aside fields managed in voluntary agri-environment schemes have the potential to improve farmland bird populations, as indicators of farmland biodiversity. We chose one, two and three year-old set-aside fields sown by a grass–legume mixture when established and selected winter cereal fields and semi-natural grasslands in Hungary as control sites. Relative abundance of birds was assessed; species were assigned to feeding guilds and classified according to their European conservation status. Species richness of herbaceous plants, cover of bare ground and vegetation height were used as covariates. Set-aside fields had higher species richness and abundance of birds compared to the adjacent winter cereal fields, similar to semi-natural grasslands. We found a positive correlation between set-aside age and farmland bird species richness and abundance. This can be explained mainly by the altered vegetation, especially the shorter vegetation height from the second year in the set-aside fields. We found no difference in the distribution pattern of species richness and abundance between feeding guilds according to set-aside age and habitat types. The wide scale application of voluntary set-aside management in agri-environment programs therefore has a high potential to mitigate the negative effects from the loss of compulsory set-aside schemes, and thus need the allocation of considerable resources in the forthcoming reformed CAP.

Rarefaction approach to analyzing distribution patterns of species richness along altitudinal gradients: a case study with arborous species data

Rarefaction approach to analyzing distribution patterns of species richness along altitudinal gradients: a case study with arborous species data

Distribution Patterns and Climatic Explanations of Species Richness of Vascular Plants in Xinjiang, China

Distribution patterns of biodiversity at large scale and their affecting factors are one of the focal issues of ecology. Xinjiang is located in an extremely arid area in northwest China,where there are ideal places to explore the distribution patterns of species richness and their affecting factors under extreme conditions because of the complicated topographical and climatic conditions and the diversity of habitats. In this study,the relationships between the distribution patterns of species richness of vascular plants and the climatic factors in Xinjiang are analyzed based on the available data of vascular plants and climatic factors. The results reveal that the species richness increases with the increase of annual precipitation (AP) and actual evapotranspiration (AET),and the curve of species richness of vascular plants with the increase of MAT and PET is unimodal. In all the subregions,species richness increases significantly with AP. Species richness patterns with the increase of MAT are different in the mountains and basins,it increases at first and then decreases with the increase of MAT in mountains,but decreases monotonically in the basins. At different water deficit (WD) levels,the increase rate of species richness is decreased with the increase of AP at high WD. Species richness increases with the increase of MAT at low WD level but decreases at high WD level.

Towards an ecologically-sustainable forestry in the Atlantic Forest

Since pristine Atlantic Forest remnants are vanishing, and biological reserves are in short, conservation of biodiversity will largely depend on proper management of the anthropogenic matrix. Here, we test (1) the effectiveness of ecologically-managed tree monocultures in maintaining Araucaria Forest biodiversity, (2) how this effectiveness change among taxa, and (3) we discuss management principles that can be used by the forestry industry in order to contribute positively to biodiversity conservation. The study was conducted in the São Francisco de Paula National Forest, southern Brazil, an environmental mosaic composed mostly of patches of Araucaria Forest and ecologically-managed monocultures of Araucaria, Pinus and Eucalyptus. Using standardized sampling methods in these four main habitats, we have recorded the richness and species composition of small mammals, birds, leaf-litter frogs, butterflies, galling insects, spiders, opiliones, flatworms, woody plants, epiphytic angiosperms, epiphytic ferns, lichens, and fruit-body producing fungi. Overall, we recorded 506 species in Araucaria Forest, 181 (36%) of which were exclusive of this habitat while 325 (64%) could be found in at least one monoculture. Distribution patterns of species richness and number of records across taxonomic groups showed that a large biodiversity can be found inside ecologically-managed plantations of Araucaria, Pinus, and Eucalyptus. For all studied taxa, except for epiphytic angiosperms and fruit-body producing fungi, more than half of the Araucaria Forest species could be found living on monocultures. We discuss how the actual management practices of the forest industry can be improved to contribute positively to the conservation of the Atlantic Forest biodiversity.

Pleuston communities are buffered from regional flood pulses: the example of ostracods in the Paraná River floodplain, Brazil

Summary1. It is widely acknowledged that sudden, large‐scale flood pulses are drivers of benthic and planktonic biodiversity change in floodplains. The impact of such pulses on pleuston (biotic communities associated with root systems of floating plants) remains to be demonstrated. Here, we investigate the effects of local and regional drivers on seasonal changes in abundance and diversity of ostracod communities in pleuston.2. Temporal and spatial distribution patterns of species richness, abundance, diversity and evenness of ostracods associated with the floating water hyacinth, Eichhornia crassipes, in a lentic environment from the upper Paraná River floodplain, were investigated in relation to local, as well as regional, environmental factors. Ostracods were sampled monthly over an annual cycle (March 2004–February 2005). Twenty‐seven species were found, representing the families Cyprididae, Candonidae, Limnocytheridae and Darwinulidae. Both diversity and abundance of ostracod communities showed seasonal changes, although species turn‐over during the year was limited.3. We tested two hypotheses concerning the causality of these fluctuations: seasonal recruitment and influx of allochthonous ostracods during the flood pulse. Our results indicate that seasonal recruitment is more likely to be the driver of fluctuations in relation to the flood pulse. We postulate that pleuston communities are buffered against possible detrimental effects of flood pulses.

Patterns of Species Richness at Varying Scales in Western Kenya: Planning for Agroecosystem Diversification

Agroforestry tree domestication research is geared at promoting diversification of on-farm tree species composition. A survey was conducted in western Kenya with the objective of exploring possibilities for diversification for a particular agroecosystem, involving a complete tree census, tree measurement and collection of ethnobotanical information in 201 small-scale farms. Various approaches to landscape diversification were explored, including random distribution of trees to increase alpha richness and species richness at higher scales in the landscape, and random distribution of species composition over villages to increase the average richness of villages. The results showed that random distribution would result in increments of average species richness in the landscape, without requiring increments of total and average abundance. A new, fast and exact method of calculating site-based species accumulation curves was presented. The method yielded results that were extremely close to classical algorithms using 10,000 randomisations. Four use-groups (beverage, fodder, charcoal and soil fertility enhancement) were identified as use-groups with alpha richness smaller than one species, but only beverage and fodder had lowest richness at all scales (fruit and construction wood joined the four use-groups of lowest average species richness at higher scales in the landscape). The novel approaches used in this study could be used in future biodiversity studies on species accumulation patterns, or on spatial distribution patterns of species richness in a landscape.

Geographical expansion and increased prevalence of common species in avian assemblages: implications for large‐scale patterns of species richness

AbstractAim The assumption that ecological patterns at large spatial scales originate exclusively from non‐anthropogenic processes is growing more questionable with the increasing domination of the biosphere by humans. Because common and rare species are known to respond differently to anthropogenic activities at local scales these differential responses could, over time, be reflected in distributional patterns of species richness at larger spatial scales. This work tests the hypothesis that modern processes have played a role in shaping these patterns, by examining recent changes in the structure and composition of assemblages of breeding avifauna over a large geographical extent.Location The portion of North America containing the contiguous United States and southern Canada.Methods Changes in the geographical range structure of breeding avifauna in North America from 1968 to 2003 were analysed in regions containing historically moderate levels of anthropogenic activities. Two geographical measures, extent of occurrence and area of occupancy, were used to identify the level of rarity or commonality of individual species and to estimate, based on a vector analysis, patterns of change in geographical range structure for individual species and avian assemblages.Results More species experienced patterns of geographical range expansion (51%) than contraction (28%). The majority of avian assemblages (43%) displayed patterns of geographical range expansion: common species increased in number and proportion (6%) in association with reciprocal losses in rare and moderately rare species, resulting in a constant level of species richness. The minority of avian assemblages (21%) displayed patterns of geographical range contraction: gains occurred for common species as well as for rare and moderately rare species, resulting in substantial increases in species richness and a decline in the proportion of common species (4%). The remaining avian assemblages presented equivocal patterns characterized by gains in the number and proportion (2%) of common species and gains in species richness.Main conclusions Modern processes have played a role in shaping the distribution patterns of species richness at large spatial scales based on the composition of common and rare species. This suggests that anthropogenic activities cannot be ignored as a possible causal factor when considering ecological patterns at large spatial scales.

Determinants of regional species richness: an empirical analysis of the number of hawkmoth species (Lepidoptera: Sphingidae) on the Malesian archipelago

AbstractAims Major patterns and determinants of the species richness of Sphingidae in the Malesian archipelago were investigated, including a distinction of richness patterns between subfamilies and range‐size classes.Location Southeast Asia, Malesia.Methods Using a compilation of specimen‐label data bases, geographic information system (GIS)‐supported estimates of distributional ranges for all Sphingidae species of Southeast Asia were used to assess the species richness of islands. Range maps for all species and checklists for 114 islands can be found at http://www.sphingidae‐sea.biozentrum.uni‐wuerzburg.de. Potential determinants of the species richness of islands were tested with general linear models.Results The estimated species richness of islands in the region is determined by biogeographical association, seasonality, availability of rain forest and island size. Species–area relationships are linear on a semi‐logarithmic representation, but not on a double‐logarithmic scale. Species richness of all sphingid subfamilies is influenced by biogeography. The presence of large rain‐forest areas affects mainly Smerinthinae, whereas distance from continental Asia is conspicuously irrelevant for this group. Widespread rather than geographically restricted species shape the overall distribution patterns of species richness. The altitudinal range of islands does not significantly affect species‐richness patterns, but its potential effects on geographically restricted species are discussed.Main conclusions As well as being affected by climatic and vegetation parameters, sphingid species richness is strongly influenced by a historical, directional dispersal process from continental Southeast Asia to the Pacific islands. This process did not apply equally to species of different taxonomic groups or range sizes. Widespread species decline in species richness towards the south‐east, whereas geographically restricted species exhibit an inverse pattern of species richness, probably because speciation becomes more important in this group within the more isolated island groups.