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1.
Soil erosion and contamination are two main desertification indices or land degradation agents in agricultural areas. Global climate change consequence is a priority to predict global environmental change impacts on these degradation risks. This agro-ecological approach can be especially useful when formulating soil specific agricultural practices based on the spatial variability of soils and related resources to reverse environmental degradation. Raizal and Pantanal models within the new MicroLEIS framework, the Ero&Con package, are database/expert system evaluation approach for assessing limitations to land use, or vulnerability of the land to specified agricultural degradation risks. This study was performed in Souma area with approximately 4100 ha extension in the North-West of Iran (west Azarbaijan). Based on 35 sampling soils, Typic Xerofluvents, Typic Calcixerepts, Fluventic Haploxerepts and Fluventic Endaquepts were classified as main subgroups. Climatological data, referred to temperature and precipitation of more than 36 consecutive years were collected from Urmieh station reports and stored in monthly Climate Database CDBm, as a major component of MicroLEIS DSS (CDBm) program. Climate data for a hypothetical future scenario were collected from the Intergovernmental Panel on Climate Change (IPCC) reports for the 2080s period. The evaluation approach predicts that attainable water erosion vulnerability classes were none (V1) very low (V2) and moderately low (V4) in the total of 72%, 13% and 15% of the Souma area, respectively and they will not affected by climate change. On contrary, attainable wind erosion vulnerability classes will increase. Also, phosphorous and heavy metal contamination vulnerability risks will not differ in two compared scenarios while nitrogen and pesticides vulnerability classes will be improved.  相似文献   

2.
基于生态位的山地农村居民点适宜度评价   总被引:24,自引:0,他引:24  
秦天天  齐伟  李云强  曲衍波 《生态学报》2012,32(16):5175-5183
为了农村居民点优化布局和公共服务资源优化配置,运用复合生态位对农村居民点适宜性进行评价。根据栖霞市山地特点以及农村居民点用地特征,基于生态位理论,从生态条件、生产条件和生活条件3方面选取相关指标,选取地形位、坡向、水源影响度、地质灾害作为生态条件的评价指标;生产条件选取工商业用地比例、工商业用地可达性、耕地和园地面积、耕地和园地可达性作为评价指标;生活条件选取农村居民点规模、城镇中心可达性和道路通达度作为生活条件评价指标。采用可达性测算、聚类分析、适宜性评价等定量分析和定性分析相结合的方法,确定适宜性等级,并与提取出的农村居民点用地相叠加,将农村居民点分为重点发展型、适度发展型、限制扩建型和优先整治型4种类型,分别占总规模的35.19%、35.10%、20.29%和9.42%。重点发展型地理位置优越,交通便捷,基础设施较完善,建议有序调整内部结构促进集约利用;适度发展型村庄处于起步阶段,受闲散地较多、土地利用方式粗放的限制,建议盘活存量用地,循环利用旧宅基地和闲置宅基地;限制扩建型受地形复杂、农业生产生活条件较差的限制,建议维持现状,引导人口外迁,推动宅基地腾退;优先整治型受地势较高、生态环境脆弱、离水源较远,交通不便,易发灾害限制,建议村庄搬迁。最后结合研究区山地农村居民点特点提出了不同类型居民点相应的调控模式。研究能够揭示农村居民点的现状和适宜性,为当前农村居民点优化布局提供理论基础,同时丰富了生态位理论在不同领域中的应用,对农村居民点优化布局具有一定的指导意义。  相似文献   

3.
蔡海生  陈艺  张学玲 《生态学报》2020,40(24):9208-9219
实施乡村振兴战略,产业兴旺是关键。立足区域富硒土壤资源禀赋优势,发展富硒农业特色经济,是振兴乡村产业的一条有效途径。以多维超体积生态位理论为指导,以区域富硒土壤资源禀赋和富硒农业发展要求为基础,从土壤自身条件、土地利用和生态保护3个方面明确了富硒土壤资源开发利用的主导因素、区位因素、限制因素;选择土壤硒含量、土壤有机质含量、地形坡度、土地利用类型、土地综合污染指数、生态保护建设等6个关键因子,构建了富硒土壤资源开发利用生态位适宜性评价指标体系;利用生态位适宜性评价相关模型,探讨了生态位适宜性单一指数和综合指数的计算方法;结合土壤利用改良分区、土壤利用功能分区、富硒农业生产分区等,分析了区域富硒土壤资源开发利用适宜性分区问题。研究可为富硒土壤资源开发利用适宜性评价提供科学可行的思路与方法,对于促进区域富硒土壤资源科学合理利用、实现富硒农业产业科学发展具有重要的指导意义和现实意义。  相似文献   

4.
物种分布模型的发展及评价方法   总被引:17,自引:0,他引:17  
物种分布模型已被广泛地应用于以保护区规划、气候变化对物种分布的影响等为目的的研究。回顾了已经得到广泛应用的多种物种分布模型,总结了评价模型性能的方法。基于物种分布模型的发展和应用以及性能评价中尚存在的问题,本文认为:在物种分布模型中集成样本选择模块能够避免模型预测过程中的过度拟合及欠拟合,增加变量选择模块可评估和降低变量之间自相关性的影响,增加生物因子以及将物种对环境的适应性机制(及扩散行为特征)和潜在分布模型进行结合,是提高模型预测性能的可行方案;在模型性能的评价方面,采用赤池信息量可对模型的预测性能进行客观评价。相关建议可为物种分布建模提供参考。  相似文献   

5.
Zhao ZX  Yan DH  Weng BS  Zhang B 《应用生态学报》2011,22(7):1907-1913
基于大鸨越冬期生境选择的相关研究成果,结合专家意见和近年来白洋淀流域大鸨的分布点记录,选择3项一级指标和13项二级指标,用以表征影响大鸨越冬生境选择的关键因子,并通过构建适宜性评价模型,对白洋淀流域大鸨越冬生境的质量进行了评价.结果表明:2005年,白洋淀流域内大鸨越冬适宜栖息地面积11907.25 km2,占流域总面积的34.1%;其中,最适宜生境面积4596.25 km2,仅占流域总面积的13.2%.研究区最适宜生境的空间分布相对集中,主要位于流域东部的白洋淀自然保护区及其周边(I区)和流域西南部的行唐、曲阳2县(II区).I区和II区中最适宜生境面积之和达2803.55 km2,占流域内最适宜生境面积的61.0%.为保护流域内大鸨的越冬生境,须重点针对上述2个区域的特点,分别采取适当措施加以保护.  相似文献   

6.
Quantitative data on the habitat characteristics of stream crayfish have been generally lacking and competing demands on water resources has created a need to address this knowledge gap. We investigated day-time habitat relationships of stream crayfish (Paranephrops planifrons White) from 793 quadrats at 30 rivers and streams in the North Island, New Zealand to develop models of koura presence–absence and abundance. The model (stepwise GAM) included width, cover, median substrate size, edge location, velocity and depth, and correctly predicted presence–absence of crayfish (8–39 mm OCL) at 73.4% of quadrats and of young-of-the-year (YOY) ≤8 mm OCL at 83.4% of quadrats. Streams ranged from 1.6 to 11.5 m in width and the probability of finding both crayfish size classes reduced sharply as streams became wider than 6 m and as the substrate became large (i.e., boulder > 256 mm). Crayfish, particularly YOY, were most likely to be found in association with cover and at the stream edge. YOY were associated with shallow depths and fine substrates, whereas larger crayfish showed a preference for cobble substrate. Undercut banks, leaf litter, tree roots, and woody debris were strongly related to the presence–absence of crayfish. The model for crayfish abundance (log-linear Poisson GAM) explained 50% of the variation between quadrats with cover, velocity, edge location, depth, and the overall crayfish abundance at each particular stream being significant variables. Highest crayfish numbers were recorded in still or slow flowing water, with the majority occurring where velocities were below 0.4 m/s. Water depths up to 0.7 m were sampled, but highest numbers were found in depths of 0.2–0.3 m. Our presence–absence model determined variables that were significant over all streams, whereas our abundance model determined variables that were significant within streams. Use of the GAMs models enabled us to untangle the multiple factors contributing to habitat selection. Cover, velocity, and locations at the stream edge were important determinants of both presence–absence and abundance. Generally, substrate was important when comparing between streams, but not within streams, whereas depth was a significant determinant of abundance within streams, but not presence–absence between streams. Handling editor: K. Martens  相似文献   

7.
Future changes in climate are imminent and they threat endangered and rare species due to habitat destruction. The Asiatic black bear (Ursus thibetanus gedrosianus) is a rare and vulnerable species whose habitat fragmentation and habitat loss decreased the size of its population significantly. Climate change is another threat to this species that is investigated in this research work. Aiming at this goal, ten species distribution models (SDMs) were applied as helpful tools for evaluating the potential effectiveness of climate change in habitat suitability of Asiatic black bear in Iran. Potential dispersal of Asiatic black bear was modeled as a function of 32 environmental variables for the current time and 2070 for 44 climate change scenarios (CC scenario) of future climate. Our results showed that modeling result depended on type of model. Our results confirmed that one of the greatest threats in the near future for Asiatic black bear was the change of suitable habitat due to climate change. All the CC scenarios showed that migration of this species would be to the north and west areas with higher elevation and that an increase in area would be more than a decrease in area in all scenarios. Recognizing and protecting potential future habitats are of the important activities to conserve this species and identify areas with conservation priority.  相似文献   

8.
In Europe, agricultural practices have progressively evolved towards high productivity leading either to the intensification of productive and accessible areas or to the abandonment of less profitable sites. Both processes have led to the degradation of semi-natural habitats like extensive grasslands, threatening species such as the Eurasian Scops Owl Otus scops that rely on extensively managed agricultural landscapes. In this work, we aimed to assess the habitat preferences of the Scops Owl using habitat suitability models combined with a multi-scale approach. We generated a set of multi-scale predictors, considering both biotic and abiotic variables, built on two newly developed vegetation management and orthopteran abundance models. To select the variables to incorporate in a ‘best multi-scale model’, we chose the best spatial scale for each variable using univariate models and by calculating their relative importance through multi-model inference. Next, we built ensembles of small models (ESMs) at 10 different scales from 50 to 1000 m, and an additional model with each variable at its best scale (‘best multi-scale model’). The latter performed better than most of the other ESMs and allowed the creation of a high-resolution habitat suitability map for the species. Scops Owls showed a preference for dry sites with extensive and well-structured habitats with 30–40% bush cover, and relied strongly on semi-extensive grasslands covering at least 30% of the surface within 300 m of the territory centre and with high orthopteran availability near the centre (50-m radius), revealing a need for good foraging grounds near the nest. At a larger spatial scale within a radius of 1000 m, the habitat suitability of Scops Owls was negatively related to forest cover. The resulting ESM predictions provide valuable tools for conservation planning, highlighting sites in need of particular conservation efforts together with offering estimates of the percentage of habitat types and necessary prey abundance that could be used as targets in future management plans to ensure the persistence of the population.  相似文献   

9.
基于GIS的秦岭山区聚落用地适宜性评价   总被引:6,自引:0,他引:6  
利用自然地理、生态和社会经济方面共14个因子构建秦岭山区聚落建设用地适宜性评价指标体系,采用AHP法确定各评价因子的权重,在地理信息系统(GIS)和遥感(RS)技术支持下,利用适宜性评价模型定量评价聚落建设用地适宜性,将聚落建设用地适宜性分为五个等级,并结合已建设区进行空缺分析。结果表明:(1)秦岭山区最适宜聚落用地面积为3378.1 km2,占研究区总面积的5.87%,说明秦岭山区适宜聚落开发的土地相对较少。(2)最适宜聚落用地集中在秦岭北、南坡山麓和东部的山间河谷地带,山地型特征明显。(3)有9.15%已建成区分布在限制建设区内,存在生态安全风险。(4)可用适宜聚落建设用地为3192.27 km2,空间分布不平衡。研究结果可为该区域城镇体系布局与用地规模的核算提供科学依据。  相似文献   

10.
The development of habitat suitability models requires a large amount of data which are rarely available. In this case, researchers need to get information on the ecological features of the studied species, based on the opinion of experts or on the literature, to construct a qualitative model. However, such models cannot be rigorously evaluated, as in most cases absence points are not available. In this paper, we assess the habitat suitability for a vulnerable insectivorous plant, Pinguicula crystallina Sibth. et Smith subsp. hirtiflora (Ten.) Strid (Lentibulariaceae) in the Campania region. Our aim was to develop an expert-based, presence-only model in support of possible conservation actions. Topographic and geological features of this species suggested by the literature were used in our model. Both the Boyce index and field surveys were chosen to evaluate the model's reliability. During field surveys, 31 absence sites and 1 new presence site were identified, and differences between sites with regard to water chemistry and quality were investigated, water being an element in the species habitat. Factors that affect reliability of the model, such as the lack of a large amount of information on the species and the limited spatial resolution of geographical information system data, are discussed.  相似文献   

11.
12.
国家公园研学旅行适宜性评价指标体系构建与实证研究   总被引:2,自引:0,他引:2  
陈东军  钟林生  肖练练 《生态学报》2020,40(20):7222-7230
国家公园兼具自然生态系统保护与教育、游憩等社会文化功能,是自然性、体验性和课程性研学旅行的潜在活动场所之一。研学旅行为国家公园的教育、游憩价值实现提供路径参考。基于"内在价值-外在条件"分析框架,根据独立性、全面性、科学性及可操作原则,选择教育价值、游憩价值、环境条件、相关设施及服务等4个因子构建国家公园研学旅行适宜性评价指标体系,并以钱江源国家公园为例进行实证分析。结果表明,国家公园的研学旅行利用应首先考虑教育价值,在完善教育、游憩等相关设施及服务的同时兼顾环境承载力及利益相关者态度等环境条件,最后考虑游憩价值;钱江源国家公园的研学旅行利用具有良好的教育及游憩价值基础,中小学生的研学旅行需求与利益相关者的支持态度等提供了外在环境条件保障,但在教育、交通及安全等方面的设施及服务有待改善。研究结果可为国家公园及其他场地的研学旅行利用规划与管理提供参考。  相似文献   

13.
内蒙古镶黄旗草地蝗虫潜在发生可能性评价   总被引:1,自引:0,他引:1  
以内蒙古草地蝗虫产卵期、越冬期和孵化期的关键气象影响因子作为草地蝗虫气象适宜度指数构建的主要因子,对内蒙古镶黄旗2010年草地蝗虫潜在发生的气象适宜性进行评价;根据当年7月上中旬在镶黄旗的实地调查资料,选取海拔、坡向、土壤类型、土壤含砂量、植被类型、植被盖度、土地覆被类型7个相对稳定的生境因子,用模糊评判方法和3S(GIS、RS、GPS)技术对该旗草地蝗虫潜在发生的生境适宜性进行评价;最后通过构建气象-生境适宜性综合评价模型,得到该旗2010年草地蝗虫潜在发生可能性(POG)等级,并用2010年实测数据和2001-2010年历史数据对模型模拟的蝗虫发生位置和蝗灾发生面积进行验证.结果表明:用本文所建气象-生境适宜性综合评价模型对镶黄旗POG等级的评价结果是可靠的.该旗草地蝗虫潜在发生的气象适宜性等级非常一致,绝大多数为适宜等级;蝗虫潜在发生源地的空间异质性主要与生境因子有关,在海拔1300~1400 m的平地/东坡/南坡、植被盖度30% ~ 50%的温带丛生禾草草原、土壤含砂量60%~80%的典型栗钙土的生境条件下,草地蝗虫潜在发生的可能性最高.  相似文献   

14.
Betula pollen is a common cause of pollinosis in localities in NW Spain and between 13% and 60% of individuals who are immunosensitive to pollen grains respond positively to its allergens. It is important in the case of all such people to be able to predict pollen concentrations in advance. We therefore undertook an aerobiological study in the city of Vigo (Pontevedra, Spain) from 1995 to 2001, using a Hirst active-impact pollen trap (VPPS 2000) situated in the city centre. Vigo presents a temperate maritime climate with a mean annual temperature of 14.9 °C and 1,412 mm annual total precipitation. This paper analyses two ways of quantifying the prediction of pollen concentration: first by means of a generalized additive regression model with the object of predicting whether the series of interest exceeds a certain threshold; second using a partially linear model to obtain specific prediction values for pollen grains. Both models use a self-explicative part and another formed by exogenous meteorological factors. The models were tested with data from 2001 (year in which the total precipitation registered was almost twice the climatological average overall during the flowering period), which were not used in formulating the models. A highly satisfactory classification and good forecasting results were achieved with the first and second approaches respectively. The estimated line taking into account temperature and a calm S–SW wind, corresponds to the real line recorded during 2001, which gives us an idea of the proposed models validity.  相似文献   

15.
Plant virus diseases cause major losses in agricultural and horticultural products, especially in tropical and subtropical regions. The first step to manage these diseases is detecting, identifying and determining the pathogen characteristics. Cucumber mosaic disease is one of the most prevalent and damaging plant diseases in the world which is caused by Cucumber mosaic virus (CMV). Each year, this virus causes yield decreasing and substantial economic damages in its host plants worldwide including the north of Iran. In order to study and identify CMV, 935 leaf samples were collected based on typical symptoms from 10 crops (tomato, pea, tobacco, soybean, watermelon, broad bean, squash, cucumber, eggplant and lettuce) in different regions of Golestan and Mazandaran provinces (north of Iran) during 2009–2010. Suspicious samples were analysed by DAS-ELISA and polyclonal antibodies. The results showed that 275 samples (29.4%) were infected by CMV. Between these hosts, the highest and the lowest CMV infection was associated to watermelon (62.44%) and lettuce (0%), respectively. Among sampling locations, Behshahr (100%) and Minoodasht (3.47%) showed the maximum and minimum infection, respectively.  相似文献   

16.
Twenty-five-year population trends of 42 bird species rare as breeders in the UK were examined in relation to changes in climatic suitability simulated using climatic envelope models. The effects of a series of potential 'nuisance' variables were also assessed. A statistically significant positive correlation was found across species between population trend and climate suitability trend. The demonstration that climate envelope models are able to retrodict species' population trends provides a valuable validation of their use in studies of the potential impacts of future climatic changes.  相似文献   

17.
Abstract

Under changing climate scenario, groundwater aquifers in the coastal areas of Pakistan are under serious threat. Looking at the gravity of the problem, and concerns of the civil society, this study was conducted to evaluate and map the quality of groundwater in the Sujawal district, a coastal area of Pakistan based on the physicochemical analysis of 94 samples using two standard numerical models and geospatial techniques. The WQI model revealed that 2.13%, 6.38%, 55.32%, 22.34%, and 13.83% of water samples were excellent, good, poor, very poor, and unsuitable for drinking purposes. Also, the SPI model identified that 32%, 13.83%, 20.12%, 18.1%, and 15.95% of samples were slightly polluted, moderately polluted, highly polluted, suitable, and unsuitable. Though the model's input is different, the proportionate of ranking revealed a significant correlation (R2=0.78) between the outcomes of both models. Overall, the study revealed that groundwater in most of the areas does not meet WHO guidelines. The prevalence of water-related diseases in the area suggests that groundwater is contaminated and using that water is of high risk for human health. The study highlights the significance of using numerical models and geospatial techniques for water quality evaluation in the coastal areas of the world.  相似文献   

18.
物种分布模型是建立在物种出现或缺失数据的基础上,但可获得的真实分布数据存在着各种各样的缺点(如:物种识别错误、坐标错误、抽样偏差、数据缺失等),影响着物种分布模型的预测性能、稳定性及应用,因此使用物种真实分布数据评估物种分布模型将带来很大的不确定性。为避免这种不确定性,越来越多的研究使用虚拟物种来评价物种分布模型的性能,评估新方法的优劣。虚拟物种是一种建立在真实(或虚拟)地理信息系统下人工生命,是简化和抽象的物种,它通过模拟物种对环境变量的响应关系,评估物种在不同环境变量下的出现概率,人为地给出虚拟的物种分布数据。虚拟物种具有数据容易获得、数据质量可控、避免过度模拟等优势,目前它被广泛用于评估物种特性、抽样偏差、地理信息、出现/缺失标准等对物种分布模型性能的影响。虚拟物种是大尺度研究中不可或缺的重要工具,有利于解决真实数据未能解决的科学问题。常用的构成算法有求和法、求积法和综合法,但这些方法可能存在补偿效应,扩大了物种的分布范围。考虑到虚拟物种的不足,提出了未来虚拟物种可能的发展方向(避免过度脱离真实,完善虚拟物种的构成算法,构建虚拟的模式生物、群落及生态系统等)。为帮助研究者快速构建虚拟物种,基于R环境开发了一个虚拟物种构成软件包(SDMvspecies)。虚拟物种可以与真实物种相结合,通过改进模型的构成方法,有利于解决一些真实数据未能解决的问题;虚拟物种的应用也将导致一些新理论的产生,有利于更好地理解生态学原理。  相似文献   

19.
In this study, a low-cost biosorbent, dead mushroom biomass (DMB) granules, was used for investigating the optimum conditions of Pb(II), Cu(II), and Ni(II) biosorption from aqueous solutions. Various physicochemical parameters, such as initial metal ion concentration, equilibrium time, pH value, agitation speed, particles diameter, and adsorbent dosage, were studied. Five mathematical models describing the biosorption equilibrium and isotherm constants were tested to find the maximum uptake capacities: Langmuir, Freundlich, Redlich-Peterson, Sips, and Khan models. The best fit to the Pb(II) and Ni(II) biosorption results was obtained by Langmuir model with maximum uptake capacities of 44.67 and 29.17 mg/g for these two ions, respectively, whereas for Cu(II), the corresponding value was 31.65 mg/g obtained with Khan model. The kinetic study demonstrated that the optimum agitation speed was 400 rpm, at which the best removal efficiency and/or minimum surface mass transfer resistance (MSMTR) was achieved. A pseudo-second-order rate kinetic model gave the best fit to the experimental data (R2 = 0.99), resulting in MSMTR values of 4.69× 10?5, 4.45× 10?6, and 1.12× 10?6 m/s for Pb(II), Cu(II), and Ni(II), respectively. The thermodynamic study showed that the biosorption process was spontaneous and exothermic in nature.  相似文献   

20.
采用景观因索赋值法(方法Ⅰ)和主成分分析法(方法Ⅱ)对大相岭山系大熊猫栖息地进行评价,结果表明。方法Ⅰ的结果中中等适宜、适宜等级和最适宜等级所占的面积分别为94.62、45.46和0.21km^2,分别占总面积的4.17%、2.00%和0.01%;而方法Ⅱ的结果中,中等适宜和适宜等级所占的面积分别为623.03和170.27km^2,分别占总面积的27.49%和7.51%。结合实际调查数据和景观因素,发现2种方法均能对大相岭山系大熊猫生境进行评价。但差异较大。方法Ⅰ评判因索较少。各因素所占比重较大,因索对整个评价结果影响很大,评价结果不精确,但所需人力、物力较少;方法Ⅱ所需评判因素较多,野外搜集所需资料困难,累计贡献率很难达到95%。而且需要大量的人力、物力。因此。为了减少评估误差。应将2种方法结合对动物生境进行评估。  相似文献   

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