考虑滑坡敏感性的天津市蓟州区生态网络构建

随着城镇水平不断提高,人口数量不断增加,滑坡、崩塌等地质灾害频发,天津市蓟州区的景观孤岛化和破碎化现象日益严重,生物多样性减少,生态价值和生态服务功能降低。以天津市蓟州区为研究区,从自然资源、气候调节、水源涵养、生物多样性等方面考虑,选取生态源地;选取坡度、地形起伏度、坡向等滑坡孕灾环境因子,基于信息量模型,在定量分析滑坡与各孕灾环境因子关系的基础上通过地图代数计算滑坡敏感性指数,并用于修正由土地利用类型赋值得到的生态基本阻力面,基于最小费用模型提取研究区生态廊道,进而构建天津市蓟州区生态网络。研究结果表明:研究区内滑坡的空间分布主要受坡度、高程、地形起伏度以及岩土类型等因素的控制;经验证基于信息量模型计算得到的滑坡敏感性指数对研究区内的滑坡具有较强的诊断能力;基于最小费用模型,提取生态廊道23条,总长度约为129 km。通过对比分析,提取的生态廊道基本上避开了滑坡灾害的高敏感性区域,能够有效地将生态源地进行连接;生态廊道在蓟州区的空间分布存在显著的差异,主要分布在蓟州区的北部山区,生态廊道的密度较高,在蓟州区的中部和南部地区,生态廊道的分布非常稀疏。研究成果将为天津市蓟州区生态网络的优化、生态安全格局的构建提供科学依据。     

Distribution, endemism and threat status of freshwater fishes in the Western Ghats of India

Aim To study (1) the large-scale distribution patterns of freshwater fishes in the Western Ghats of India; (2) the endemism and uniqueness of the fishes in various zones; and (3) the threat status of fishes by categorizing them under low risk (LR), vulnerable (VU), endangered (EN) and critically endangered (CR). Location The Western Ghats of India. Methods The scientific literature describing the freshwater fishes of the Western Ghats was reviewed. Data describing the lists of the species were extracted and complied. The species accumulation curve was plotted using Michaelis–Menten-like equation. The Western Ghats was divided into six zones and similarity of the species was calculated using Jacquard's index. Results Literature to date records 288 species belonging to 12 orders, 41 families and 109 genera, of which 118 species are endemic and 51 are unique. However, the species accumulation curve shows that there might be 345 species in this region, indicating that 16% species have not been recorded to date. An analysis of the distribution pattern of fishes in the Western Ghats suggests that the southern region is more diverse than the northern and central regions. The southern region shows high endemism and high uniqueness while the northern region shows high endemism but less uniqueness. The similarity index between the zones indicates that as the distance between the zones increases similarity decreases. The status of 105 of 288 species was not known due to data deficiency but among the remaining 183 species, 58 species were categorized as LR, 41 as VU, 54 as EN, 24 as CR while the remaining six species were introduced. Conclusions The distribution patterns of fishes in the Western Ghats are discussed in accordance with the geography of Western Ghats, its climatic conditions and ‘Satpura Hypothesis’. The threat status of fishes found in Western Ghats suggests that at least 41% of fish fauna is threatened by either being VU, EN or CR. Implication of potent conservation measures is necessary to conserve the fish fauna of Western Ghats.     

Pinda shrirangii,a new elegant species of Apiaceae from the northern Western Ghats,India

A new species, Pinda shrirangii Gosavi & Chandore, is described and illustrated from a high-elevation region of northern Western Ghats, India. The new species is closely allied to the only other species in the genus, Pinda concanensis (Dalzell) P.K.Mukh. & Constance which was also described from the northern Western Ghats of Maharashtra state of India. Coloured photographs and illustrations are provided to facilitate the identification.     

多尺度滑坡灾害生态风险评价与风险管理——以三峡库区万州-巫山段为例

进行生态风险多尺度综合评价,对环境管理及风险决策具有重要意义。以三峡库区滑坡重点监测县域为例,基于“危险性-脆弱性-潜在损失”三维模型,以随机森林模型评估滑坡危险性,采用景观格局指数表征生态脆弱性,利用生境质量核算潜在生态损失,进行格网、行政、子流域多尺度下的滑坡灾害生态风险评价,提出适合各尺度的风险管理措施,在此基础上选择最适宜尺度并结合研究区实际情况进行验证。结果表明,生态风险等级较高区域集中于长江两岸沿线,三峡库区建设对研究区滑坡生态风险产生较大影响;两两尺度风险分布结果具有一定相似性,而三种尺度共同作用结果又存在一定差异;子流域尺度在保证生态结构完整性的前提下评价结果好于其他两种尺度,更适合三峡库区县域的生态风险评价;研究区东部风险防范类型相对单一,而西部风险防范类型较多,需做到精细化管理。研究增加了多尺度综合评价实例,对今后开展整个三峡库区滑坡生态风险研究奠定一定理论和实践基础。     

Does disturbance affect the structure of tropical fish assemblages? A test using null models

Null model analyses on fish presence-absence data from tropical river assemblages of the Western Ghats, India, revealed a difference in the extent of randomness in species assemblage structure among impacted and unimpacted rivers in the region.     

Remarkable genetic homogeneity in unstriped, long-tailed Ichthyophis along 1500 km of the Western Ghats, India

The mountainous Western Ghats are part of a biodiversity hotspot and extend for about 1600 km, lying close and subparallel to the west coast of peninsular India. The region is a centre of diversity for amphibians, and recent preliminary work on some components of both caecilian (Gymnophiona) and frog (Anura) fauna is indicative of a high degree of local endemism. We investigated diversity in mitochondrial rRNA 12S and 16S sequences for long-tailed, unstriped Ichthyophis (Amphibia: Gymnophiona: Ichthyophiidae) that potentially represent four taxonomically confused and poorly known endemic caecilian species. Data were analysed for18 individuals from along c . 1500 km of the Western Ghats region. Genetic diversity is remarkably low, with a maximum uncorrected p -distance of 0.5%. These DNA sequences and new morphological data do not allow us to reject the null hypothesis that the sample comprises only a single, widely distributed, highly interconnected species. The phylogenetic signal among the data is extremely low. However, population genetic analyses reveal that the Palghat Gap, a c . 30 km discontinuity in the Western Ghats considered to be significant in the biogeography of other organisms occurring in this region, corresponds to a significant subdivision of long-tailed, unstriped Ichthyophis into two groups.     

Endemic Asian Chytrid Strain Infection in Threatened and Endemic Anurans of the Northern Western Ghats,India

The Western Ghats of India harbors a rich diversity of amphibians with more than 77% species endemic to this region. At least 42% of the endemic species are threatened due to several anthropogenic stressors. However, information on amphibian diseases and their impacts on amphibian populations in this region are scarce. We report the occurrence of Batrachochytridium dendrobatidis (Bd), an epidermal aquatic fungal pathogen that causes chytridiomycosis in amphibians, from the Western Ghats. In the current study we detected the occurrence of a native Asian Bd strain from three endemic and threatened species of anurans, Bombay Night Frog Nyctibatrachus humayuni, Leith''s Leaping Frog Indirana leithii and Bombay Bubble Nest Frog Raorchestes bombayensis, for the first time from the northern Western Ghats of India based on diagnostic nested PCR, quantitative PCR, DNA sequencing and histopathology. While, the Bd infected I. leithii and R. bombayensis did not show any external symptoms, N. humayuni showed lesions on the skin, browning of skin and sloughing. Sequencing of Bd 5.8S ribosomal RNA gene, and the ITS1 and ITS2 regions, revealed that the current Bd strain is related to a haplotype endemic to Asia. Our findings confirm the presence of Bd in northern Western Ghats and the affected amphibians may or may not show detectable clinical symptoms. We suggest that the significance of diseases as potential threat to amphibian populations of the Western Ghats needs to be highlighted from the conservation point of view.     

The dendrogeomorphic spatio-temporal reconstruction of flow-like landslides activity in one of the most susceptible region of Central Europe (the Vsetínské vrchy Mts.)

Flow-like landslides are a dangerous landslide type. They often express gradual movement or seeming dormancy, but occasional reactivation can, in extreme cases, result in catastrophic events. To predict their future behaviour, knowledge of past spatio-temporal development and relationships with hydrometeorological triggers is crucial. Moreover, regional data are more robust than case studies. Dendrogeomorphic (tree-ring-based) methods are a very precise approach for reconstructing past landslide behaviour. Nevertheless, regional reconstructions are very rare, which is probably due to their time-consuming procedures. This paper presents the results of a regional tree-ring-based reconstruction of the spatio-temporal development of flow-like landslides in a selected region in the Outer Western Carpathians. Six selected landslides were studied via analysis of 614 increment cores that came from 307 disturbed trees. The reconstruction provided data for approximately 70 individual landslide reactivation phases that were distributed in 44 event years. Events with regional extension (at least half of the studied landslides were active) were detected in six years (1940, 1941, 1953, 1961, 1985, and 1997). Periods of increased (1950s, 1990s) as well as decreased (1940s, 1970s, 2010s) landslide activity were reconstructed. The use of tree-ring data enabled the construction of landslide probability maps. Based on this analysis, all studied landslides exhibit extremely high probabilities of reactivation during a temporal horizon of 100 years, but even over shorter periods (5 and 20 years), their probability of reactivation is very high. Finally, analysis of meteorological triggers suggests the positive effect of precipitation in May (and possibly in September) to activate landslides with regional extent. Extreme short-duration (1-day) precipitation events probably do not play a role in landslide triggering. Moreover, gradual increases in precipitation totals during periods of at least one-half year preceding the event years were detected.     

Ecological Risk Assessment of Regions Along the Roadside of the Qinghai-Tibet Highway and Railway Based on an Artificial Neural Network

A concept model of regional risk was constructed for the characteristics of ecosystems alongside the Qinghai-Tibet highway and railway based on the MLP (Multilayer perceptron) model. Seven indices such as snow hazard, drought hazard, and landslide were selected in order to evaluate the integrated ecological risk of the ecosystems along the study area. Results show that the Qaidam montane desert zone had the greatest average risk value (4.26), followed by the Golog-Nagqu high-cold scrub meadow zone (2.80) and the East Qinghai and Qilian montane steppe zone (2.73) among the ecosystems within the six natural zones within the study region. As far as land cover types are concerned, the top three ecological risk values appear in the needle-leaved forest (4.31), desert (4.12), and land without vegetation (3.62), which are higher than those in the other seven types in the study site. Although the risk values are influenced by natural factors and human activities, they are more strongly controlled by natural factors. According to the ecological risk characteristics, the ecosystems within the study area are subdivided into four subregions, including the Qaidam basin region (high risk), the Xidatan to Damxung region (moderate risk), and the Eastern Qinghai-Qilian (slight risk) and Southern Xizang (Tibet) region (slighter risk).     

A new species of Eugenia (Myrtaceae) from the Western Ghats, India

Eugenia shettyana, is described and illustrated as a new species from the Western Ghats, India. The differences to similar taxa are discussed.     

A unique radiation of marine littorinid snails in the freshwater streams of the Western Ghats of India: the genus Cremnoconchus W.T. Blanford, 1869 (Gastropoda: Littorinidae)

The caenogastropod family Littorinidae is almost exclusively marine, but a unique freshwater genus, Cremnoconchus, is known from India. Its members are restricted to montane streams on the western escarpment of the Western Ghats, at altitudes between 300 and 1400 m. Four species and several varieties were described in the 19th century, but no taxonomic study has been carried out for over 120 years and the last anatomical report was in 1935. Nevertheless, they are of unusual evolutionary interest and also of conservation concern as a genus endemic to the Western Ghats biodiversity hotspot. Based on anatomical study of newly collected material and examination of historical and type specimens, we present a systematic revision of Cremnoconchus, illustrating shells, radulae, and reproductive anatomy. The very large eggs, invaginated penial filament, and calcified operculum are unique among Littorinidae. Three valid, described species (C. syhadrensis, C. conicus, C. canaliculatus) are recognized in the northern Western Ghats in Maharashtra state, where all can occasionally be found sympatrically. We describe an additional six new species from the central Western Ghats in a small area (linear distance 80 km) of Karnataka state, over 500 km south of the previously known range of the genus. Here the species each appear to be restricted to a single drainage system. Because of their highly restricted distribution and fragile habitat, this radiation of nine species is judged to be endangered. © 2013 The Linnean Society of London     

Distribution pattern, endemism, threat status and conservation measures of fishes in the Tunga and Bhadra rivers of Western Ghats, India

This study documents the distribution patterns, endemism and uniqueness (species richness) of fishes in the Tunga and Bhadra rivers of Western Ghats, India. We recorded 77 species represented by 7 orders, 16 families and 44 genera, of which 36 species are endemic to Western Ghats, 12 species endemic to India and 26 species endemic to the Indian Subcontinent. Based on our analysis on the distribution patterns, the Tunga River is richer in diversity and higher in endemism than the Bhadra. We calculated the similarity of the species composition among sites within these two rivers using the Jacquard index. The similarity index between the sampling sites of these rivers revealed that the similarity decreases with increasing distance between the sampling sites. Of the 77 fish species we collected, 8 species (11.1%) are in the Critical category, 10 species (13.8%) are in the High Risk category, 36 species (50%) are in the Moderate category and the remaining 18 species (25%) are at lower risk. The threat status of fishes found in the Tunga and Bhadra rivers strongly suggests the need for effective conservation measures to conserve the fish species richness of these rivers.     

An evaluation of landslide susceptibility using probability statistic modeling and GIS's spatial clustering analysis

As landslides caused multiple casualties and destructions on a global scale, various models were applied to landslide susceptibility evaluation. In this study, a probability statistic model called the certain factor was adopted to assess the landslide susceptibility of Danba, a county in southwestern China, where the landslide events occur frequently but were poorly understood in regional landslide susceptibility. With the validation of area under the prediction rate curve, the resulting susceptibility map has the accuracies of 0.8211 and 0.8288 in experiment area and verification area, respectively. The validated assessment result was further processed to identify landslide-prone areas with the aid of the spatial clustering analysis of geographic information system. Two clustering indexes including Moran's I statistic and local indicator of spatial association (LISA) were involved. The Moran's I index of 0.959 and the LISA identification result accordant with previous investigations proved that the proposed method was rational and efficient to find the landslide-prone regions and make relevant decisions.     

Diversity of Bacillus thuringiensis Isolated from Western Ghats of Tamil Nadu State, India

The Western Ghats of India is the one of the world’s 10 “Hottest biodiversity hotspots” that runs along the western part of India through four states including Tamil Nadu. The only biodiversity reserve in the Western Ghats is the Nilgiri biosphere located in the Tamil Nadu state. In the present study, 525 soil samples were collected from all the 14 different divisions of the Western Ghats in Tamil Nadu state, India. A total of 316 new isolates of Bacillus thuringiensis (Bt) that produce parasporal crystalline inclusions were isolated from 525 soil samples. Seven different types of crystalline inclusions were observed in the 316 new isolates of Bt. Cuboidal inclusion was predominantly present in 26.9% of the Bt isolates when compared to other shapes. Further characterization of 70 of the 316 Bt isolates for crystal protein profile through SDS-PAGE revealed six different types of crystal protein profile viz., 135 and 65, 135, 95, 65, 43, and 30 kDa crystal proteins. Variation in the mass of crystal protein(s) purified from the isolates of Bt revealed molecular diversity of this bacterium prevalent in the Western Ghats of Tamil Nadu, India.     

A new species of Oberonia (Orchidaceae) from Western Ghats of Kerala,India

A new Oberonia species, O. muthikulamensis (Orchidaceae), is described and illustrated from Muthikulam forest, Western Ghats of Kerala, India. It is compared with a closely morphologically similar species, O. sebastiana, endemic to Western Ghats.     

A new species of Beilschmiedia (Lauraceae) from the Western Ghats,India

Beilschmiedia tirunelvelica is described and illustrated as a new species from the Western Ghats of Agasthiyamalai Biosphere Reserve, India. The differences to similar taxa are provided with dichotomous key and table.     

Elevational gradients of reptile richness in the southern Western Ghats of India: Evaluating spatial and bioclimatic drivers

Exploring elevational patterns in species richness and their underlying mechanisms is a major goal in biogeography and community ecology. Reptiles can be powerful model organisms to examine biogeographical patterns. In this study, we examine the elevational patterns of reptile species richness and test a series of hypotheses that may explain them. We sampled reptile communities along a tropical elevational gradient (100–1,500 m a.s.l.) in the Western Ghats of India using time‐constrained visual encounter surveys at each 100‐m elevation zone for 3 years. First, we investigated species richness patterns across elevation and the support of mid‐domain effect and Rapoport's rule. Second, we tested whether a series of bioclimatic (temperature and tree density) and spatial (mid‐domain effect and area) hypotheses explained species richness. We used linear regression and AICc to compare competing models for all reptiles, and each of the subgroups: snakes, lizards, and Western Ghats’ endemics. Overall reptile richness and lizard richness both displayed linear declines with elevation, which was best explained by temperature. Snake richness and endemic species richness did not systematically vary across elevation, and none of the potential hypotheses explained variation in them. This is the first standardized sampling of reptiles along an elevational gradient in the Western Ghats, and our results agree with the global view that temperature is the primary driver of ectotherm species richness. By establishing strong reptile diversity–temperature associations across elevation, our study also has implications for the impact of future climate change on range‐restricted species in the Western Ghats.     

Spatial analysis of endemism to redefine conservation areas in Western Ghats (India)

A meaningful effort for the preservation of endemism would require a deep understanding of its related mechanisms and an accurate estimation of its spatial distribution. Here, we applied methods dedicated to species distribution modelling (SDM) to map an integrated index in India's Western Ghats biodiversity hotspot, the endemic tree richness, and to use it for recommendations of protected areas. We then rigorously compared SDM results with spatially explicit and multiscale comparison tools, among them the cutting-edge correlation map and profile (CMP) technique, to finally draw up an endemic richness map with improved accuracy.The endemic richness showed a sharply increasing southward gradient in the Western Ghats, mainly driven by the seasonality of the temperature and the precipitation's stability. This precise quantification of the tree endemism pattern in peninsular India helped in identifying vulnerable areas in terms of conservation of biodiversity as a whole. The Indian authorities recently used our recommendations to extend protected areas in the southern tip of the Indian peninsula to conserve this endemic richness. We believe that spatial analyses and multiscale comparison tools such as those presented here can help conservationists everywhere to better cope with the difficulties met in identifying zones for protected status.     

Ecological niche modeling for conservation planning of an endemic snail in the verge of becoming a pest in cardamom plantations in the Western Ghats biodiversity hotspot

Conservation managers and policy makers are often confronted with a challenging dilemma of devising suitable strategies to maintain agricultural productivity while conserving endemic species that at the early stages of becoming pests of agricultural crops. Identification of environmental factors conducive to species range expansion for forecasting species distribution patterns will play a central role in devising management strategies to minimize the conflict between the agricultural productivity and biodiversity conservation. Here, we present results of a study that predicts the distribution of Indrella ampulla, a snail endemic to the Western Ghats biodiversity hotspot, which is becoming a pest in cardamom (Ellettaria cardamomum) plantations. We determined the distribution patterns and niche overlap between I. ampulla and Ellettaria cardamomum using maximum entropy (MaxEnt) niche modeling techniques under current and future (2020–2080) climatic scenarios. The results showed that climatic (precipitation of coldest quarter and isothermality) and soil (cation exchange capacity of soil [CEC]) parameters are major factors that determine the distribution of I. ampulla in Western Ghats. The model predicted cardamom cultivation areas in southern Western Ghats are highly sensitive to invasion of I. ampulla under both present and future climatic conditions. While the land area in the central Western Ghats is predicted to become unsuitable for I. ampulla and Ellettaria cardamomum in future, we found 71% of the Western Ghats land area is suitable for Ellettaria cardamomum cultivation and 45% suitable for I. ampulla, with an overlap of 35% between two species. The resulting distribution maps are invaluable for policy makers and conservation managers to design and implement management strategies minimizing the conflicts to sustain agricultural productivity while maintaining biodiversity in the region.     

The effect of climatic gradients, topographic variation and species traits on the beta diversity of rain forest trees

Aim  We assessed the rates of turnover of tree species with distance (beta diversity) in wet forests of the Western Ghats (WG) complex of India to see whether climate, topographic variation or species traits influence beta diversity.
Location  The Western Ghats is a chain of mountains about 1600 km in length, running parallel to the western coast of the Indian Peninsula from above 8° N to almost 21° N latitude.
Methods  We used data from 60 small plot inventories concentrated in three regions: the southernmost part of the Western Ghats (SWG) (8°24' to 9°37' N), the Nilgiri Hills (11°12' to 11°14' N), and the central Western Ghats (CWG) (12°32' to 14°51' N). We used Sorensen's index (SI) to estimate the similarity in species composition between two plots and regressed SI against the logarithm of the distance between plots to assess beta diversity. A bootstrapping procedure provided confidence intervals for regression coefficients. To test for the effects of climate, we regressed seasonality differences between plots against SI for low-elevation (< 800 m) plots along the north–south axis, and all plots in the SWG. We assessed the impact of the rainfall gradient in the Kogar region.
Results  Among all three regions, beta diversity was highest along the latitudinal axis, and along the rainfall gradient in the Kogar region. Differences in seasonality between sites were strongly related to beta diversity along the north–south seasonality gradient and within the SWG. Within the three regions, beta diversity was highest in the region with the strongest rainfall gradient and lowest for the topographically heterogeneous SWG. Beta diversity did not differ between forest strata and dispersal modes.
Main conclusions  We conclude that climate, particularly seasonality, is probably the primary driver of beta diversity among rain forest trees of the Western Ghats complex.