Habitat suitability and protection status of four species of amphibians in the Dominican Republic     

《Applied geography (Sevenoaks, England)》2015

Hispaniola Island has both a high level of amphibian endemism, and a high level of habitat degradation due to agriculture, infrastructure development, and extractive industries. The objective of this work was to evaluate the capacity of Dominican Republic's current network of protection to maintain the habitat of four species of amphibians endemic to Hispaniola (Osteopilus pulchrilineatus, Osteopilus vastus, Hypsiboas heilprini, and Eleutherodactylus flavescens). Spatial analysis was performed to relate observations of the target species to environmental factors using a maximum entropy algorithm (Maxent). Results of this analysis produced maps of probability of occurrence for each species. Analysis of habitat degradation was based on a change analysis of vegetation, by evaluating trends in the normalized difference vegetation index (NDVI) between 2000 and 2011. Results show that forest loss and species habitat loss within protected areas are smaller but similar to those extracted for the country as a whole, suggesting that the current protected area network is not effective for the maintenance of the habitat of the amphibians analyzed. Enforcement of established protection and restoration within current protected areas could facilitate the protection of up to 25.7% of target amphibian habitat. The methodologies presented here can be applied to measure biodiversity offset effectiveness.  相似文献   

Mapping the stray domestic cat (Felis catus) population in New Zealand: Species distribution modelling with a climate change scenario and implications for protected areas     

《Applied geography (Sevenoaks, England)》2015

Species distribution models of stray cats were developed using two types of occurrence data: (i) a combined dataset of stray cats and cat colonies in Auckland and projected to the wider New Zealand area; and (ii) population density as an analogue for country-wide stray cat occurrence. These occurrence data, together with sets of environmental variables were used as input to the Maxent modelling tool to produce maps of suitability for the species. Environmental variables used in the models consist of current bioclimatic conditions, and a future climate scenario (RCP8.5 for year 2070 CCSM model). Commonly occurring bias in the modelling process due to latitude, the area for selecting background points in model evaluation, inherent spatial autocorrelation of occurrence points, and correlated bioclimatic variables were explicitly addressed. Results show that the North Island consistently provide more suitable areas for stray cats with increased suitability in a high emission climate change condition. Key protected areas at risk from the increased suitability to stray cats are also presented.  相似文献   

Hydroid assemblages from the Southwestern Atlantic Ocean (34–42° S)     

Gabriel N. Genzano  Diego Giberto  Laura Schejter  Claudia Bremec  & Pablo Meretta 《Marine Ecology》2009,30(1):33-46

This paper provides updated taxonomic knowledge about hydrozoan species and provides ecological information including geographical and bathymetric distributions and biological substrata for the various hydroid assemblages from the Sub-Antarctic Biogeographical Region, mainly Buenos Aires and the Uruguayan coasts. Five of the 41 species found are new records for the study region. Thirty-one species (75.6%), all found at depths of less than 80 m, have cosmopolitan distributions. Biodiversity decreased markedly below 80 m depth, where nine species (≈22%) distributed in the Southern hemisphere and one endemic species (2.4%) were found. Most species were non-specific epizoites, occurring on diverse substrata. A non-parametric multivariate similarity analysis revealed nine species groups that were correlated with large-scale and local oceanographic patterns and with the availability of suitable substrata. The main hydroid substrata for eight of the groups were cnidarians, molluscs (mainly blue mussels), quartzite rocks and sponges. In a single group found in Patagonian scallop beds, the main biological substrata were polychaete tubes, other hydroids and scallops.  相似文献   

Assessing Worldview-3 multispectral imaging abilities to map the tree diversity in semi-arid parklands     

《International Journal of Applied Earth Observation and Geoinformation》2020

Semi-arid parkland agrosystems are strongly sensitive to climate change and anthropic pressure. In the context of sustainability research, trees are considered critical for various ecosystem services covering environment quality as well as food security and health. But their actual ecological impact on both cropland and natural vegetation is not well understood yet, and collecting spatial and structural information around agroforestry systems is becoming an important issue. Tree mapping in semi-arid parklands could be one of these prerequisites. While for obtaining an exhaustive inventory of individual trees and for analysing their spatial distribution, remote sensing is the ideal tool. However, it has been noted that depending on the spatial resolution and sensor spectral characteristics, tree species cannot be distinguished clearly, even in the sparsely vegetated semi-arid ecosystems of West Africa. Thus, this work focuses on assessing the capabilities of Worldview-3 imagery, acquired in 8 spectral bands, to detect, delineate, and identify certain key tree species in the Faidherbia albida parkland in Bambey, Senegal, based on a ground-truth database corresponding to 5000 trees. The tree crowns are delineated through NDVI thresholding and consecutive filtering to provide object-based radiometric signatures, radiometric indices, and textural information. A factorial discriminant analysis is then performed, which indicates that only four out of the seven most abundant species in the study area can be discriminated: “Faidherbia albida”,” Azadirachta indica”, “Balanites aegyptiaca” and “Tamarindus indica”. Next, random forest and support vector machine classifiers are employed to identify the optimal combination of classifier parameters to discriminate these classes with a high accuracy, robustness, and stability. The linear support vector machine with cost=1 and gamma=0.01 provides the optimal results with a global accuracy of 88 % and kappa of 0.71. This classifier is applied to the whole study area to map all the trees with crowns larger than 2 m, sorted in four identified species and a fifth common group of unidentified species. This map thus enables analysing the variability in tree density and the spatial distribution of different species. Such information can afterwards be correlated to the ecological functioning of the parkland and local practices, and offers promising opportunities to help future sustainability initiatives in different socio-ecological contexts.  相似文献   

Predictive mapping of mosquito distribution based on environmental and anthropogenic factors in Taita Hills,Kenya     

《International Journal of Applied Earth Observation and Geoinformation》2019

Mosquitoes are vectors for numerous pathogens, which are collectively responsible for millions of human deaths each year. As such, it is vital to be able to accurately predict their distributions, particularly in areas where species composition is unknown. Species distribution modeling was used to determine the relationship between environmental, anthropogenic and distance factors on the occurrence of two mosquito genera, Culex Linnaeus and Stegomyia Theobald (syn. Aedes), in the Taita Hills, southeastern Kenya. This study aims to test whether any of the statistical prediction models produced by the Biomod2 package in R can reliably estimate the distributions of mosquitoes in these genera in the Taita Hills; and to examine which factors best explain their presence. Mosquito collections were acquired from 122 locations between January–March 2016 along transects throughout the Taita Hills. Environmental-, anthropogenic- and distance-based geospatial data were acquired from the Taita Hills geo-database, satellite- and aerial imagery and processed in GIS software. The Biomod2 package in R, intended for ensemble forecasting of species distributions, was used to generate predictive models. Slope, human population density, normalized difference vegetation index, distance to roads and elevation best estimated Culex distributions by a generalized additive model with an area under the curve (AUC) value of 0.791. Mean radiation, human population density, normalized difference vegetation index, distance to roads and mean temperature resulted in the highest AUC (0.708) value in a random forest model for Stegomyia distributions. We conclude that in the process towards more detailed species-level maps, with our study results, general assumptions can be made about the distribution areas of Culex and Stegomyia mosquitoes in the Taita Hills and the factors which influence their distribution.  相似文献   

Responses of diff erent biodiversity indices to subsampling efforts in lotic macroinvertebrate assemblages     

WANG Jun  LI Zhengfei  SONG Zhuoyan  ZHANG Yun  JIANG Xiaoming  XIE Zhicai 《海洋湖沼学报（英文）》2019,(1):122-133

As a less time-consuming procedure, subsampling technology has been widely used in biological monitoring and assessment programs. It is clear that subsampling counts af fect the value of traditional biodiversity indices, but its ef fect on taxonomic distinctness(TD) indices is less well studied. Here, we examined the responses of traditional(species richness, Shannon-Wiener diversity) and TD(average taxonomic distinctness: Δ +, and variation in taxonomic distinctness: Λ +) indices to subsample counts using a random subsampling procedure from 50 to 400 individuals, based on macroinvertebrate datasets from three dif ferent river systems in China. At regional scale, taxa richness asymptotically increased with ?xed-count size; ≥250–300 individuals to express 95% information of the raw data. In contrast, TD indices were less sensitive to the subsampling procedure. At local scale, TD indices were more stable and had less deviation than species richness and Shannon-Wiener index, even at low subsample counts, with ≥100 individuals needed to estimate 95% of the information of the actual Δ + and Λ + in the three river basins. We also found that abundance had a certain ef fect on diversity indices during the subsampling procedure, with dif ferent subsampling counts for species richness and TD indices varying by regions. Therefore, we suggest that TD indices are suitable for biodiversity assessment and environment monitoring. Meanwhile, pilot analyses are necessary when to determine the appropriate subsample counts for bioassessment in a new region or habitat type.  相似文献   

河北坝上风蚀沙化地区固沙造林植物种的选择   总被引：3，自引：0，他引：3  

赵存玉  康春凤 《中国沙漠》1999,19(1):63-67

通过对河北坝上沙地植被的调查和固沙造林植物种的引种栽植试验,指出适于坝上沙地固沙造林的植物种有9种。适应性强的有褐沙蒿、山竹子两个乡土植物种和华北落叶松、樟子松、沙棘、黄柳;适应性中等的有小叶锦鸡儿、沙柳、花棒;适应性弱的有沙地柏、紫穗槐。  相似文献   

不同地形部位喀斯特森林物种多样性的比较研究――以贵州茂兰自然保护区为例   总被引：6，自引：2，他引：4  

龙翠玲 《中国岩溶》2007,26(1):55-60

选择茂兰国家级喀斯特森林自然保护区为研究对象,对区内不同地形部位的植被进行群落学调查,分析了不同地形部位的植物物种多样性特征,并对喀斯特森林物种多样性维持机制进行探讨。结果表明: ( 1)槽谷森林的物种数S、丰富度指数R 1及物种多样性指数H′最大,分别为76、4. 477和5. 102;其次为漏斗森林,分别为68、4. 059和5. 024;坡地森林的最小,分别为64、3. 110和4. 886。漏斗森林的均匀度指数J 最大,为0. 825,其次为槽谷森林,为0. 816,坡地的相对较小,为0. 814。生态优势度指数λ与均匀度指数相反。( 2)三种地形部位喀斯特森林均以灌木的物种丰富度和多样性指数最大,其次为草本和藤本植物,乔木的最小。( 3)多样性指数随地形部位的变异程度草本植物和灌木物种大于乔木和藤本植物物种。喀斯特生境的高度异质性是喀斯特森林物种多样性维持的基础。   相似文献   

DNA条形码技术在鱼类浮游生物鉴定中的应用及研究展望          下载免费PDF全文

刘守海  程祥圣  何彦龙  秦玉涛 《海洋开发与管理》2018,35(7):56-62

鱼类浮游生物的准确鉴定是鱼类浮游生物研究的基础。传统的基于形态特征的鉴定不仅费时费力,而且由于缺乏足够信息,鉴定存在困难,导致物种多样性被低估。为了对物种进行准确、快速地鉴定,急需在传统形态分类学基础上,建立并结合便捷准确的分子鉴定手段。DNA条形码技术是利用一段较短的DNA序列实现快速准确物种鉴定的工具,就像在商店里扫描仪读取条形码那样,对每一种生物也能通过快速分析其DNA中的一小段(线粒体细胞色素c氧化酶I亚基,mt COI)加以识别。DNA条形码提供了可信息化的分类标准和有效的分类学手段,已成为近年来生物类群的研究热点。文章介绍了DNA条形码的概念、原理、工作流程及其优点,分析了其在鱼类浮游生物鉴定中的应用可行性,并展望未来鱼类浮游生物学发展的前景:分子技术鉴定鱼类浮游生物相关规范标准的建立,传统形态鉴定与分子方法相结合的分类学研究,以及鱼类浮游生物的生态学研究。  相似文献   

2004年夏季中国南海北部的浮游植物   总被引：24，自引：1，他引：24  

乐凤凤  孙军  宁修仁  宋书群  蔡昱明  刘诚刚 《海洋与湖沼》2006,37(3):238-248

报道了2004年夏季南海北部18个大面测站浮游植物的调查结果。应用Utermhl方法初步鉴定出浮游植物4门74属159种,平均细胞丰度为(115.05±438.89)×103个/L(n=91),其中硅藻在物种丰富度和细胞丰度上占绝对优势;其次为甲藻。主要优势种为柔弱伪菱形藻Pseudo-nitzschiadelicatissima、旋链角毛藻Chaetoceroscurvisetus、皇冠角毛藻Chaetocerosdiadema、具齿原甲藻Prorocentrumdentatum和冰河拟星杆藻Asterionellopsisglacialis。调查区浮游植物表层细胞丰度的平面分布从沿岸向外海迅速减少,高值区分布在广东沿岸和珠江口附近海域。同1999年同期资料相比,浮游植物细胞丰度增加1倍,但平面分布趋势相同。调查区浮游植物垂直分布总体特征是由水体表层到底层,细胞丰度逐渐减少。细胞丰度密集区位于水体表层,但是只有S2断面出现了次表层最大值现象,其垂直剖面分布同叶绿素a、铵盐、溶解氧以及盐度密切相关。整个调查区浮游植物的多样性程度是低的。  相似文献