共查询到20条相似文献，搜索用时 15 毫秒
1.
Thomas J. Leininger Alan E. Gelfand Jenica M. Allen John A. Silander Jr. 《Journal of Agricultural, Biological & Environmental Statistics》2013,18(3):314-334
Compositional data analysis considers vectors of nonnegative-valued variables subject to a unit-sum constraint. Our interest lies in spatial compositional data, in particular, land use/land cover (LULC) data in the northeastern United States. Here, the observations are vectors providing the proportions of LULC types observed in each 3 km×3 km grid cell, yielding order 104 cells. On the same grid cells, we have an additional compositional dataset supplying forest fragmentation proportions. Potentially useful and available covariates include elevation range, road length, population, median household income, and housing levels. We propose a spatial regression model that is also able to capture flexible dependence among the components of the observation vectors at each location as well as spatial dependence across the locations of the simplex-restricted measurements. A key issue is the high incidence of observed zero proportions for the LULC dataset, requiring incorporation of local point masses at 0. We build a hierarchical model prescribing a power scaling first stage and using latent variables at the second stage with spatial structure for these variables supplied through a multivariate CAR specification. Analyses for the LULC and forest fragmentation data illustrate the interpretation of the regression coefficients and the benefit of incorporating spatial smoothing. 相似文献
2.
Carlo Gaetan Matteo Grigoletto 《Journal of Agricultural, Biological & Environmental Statistics》2007,12(4):434-449
In this article, we propose a spatial model for analyzing extreme rainfall values over the Triveneto region (Italy). We assess
the existence of a long-term trend in the extremes. To integrate data coming from the different stations, we propose a hierarchical
model. At the first level, for each monitoring station we model data by making use of a generalized extreme value distribution;
at the second level, we combine results from the first stage by exploiting recent advances in modeling nonstationary spatial
random fields. 相似文献
3.
Raymond A. Webster Kenneth H. Pollock Theodore R. Simons 《Journal of Agricultural, Biological & Environmental Statistics》2008,13(2):121-139
We present a unified framework for modeling bird survey data collected at spatially replicated survey sites in the form of repeated counts or detection history counts, through which we model spatial dependence in bird density and variation in detection probabilities due to changes in covariates across the landscape. The models have a complex hierarchical structure that makes them suited to Bayesian analysis using Markov chain Monte Carlo (MCMC) algorithms. For computational efficiency, we use a form of conditional autogressive model for modeling spatial dependence. We apply the models to survey data for two bird species in the Great Smoky Mountains National Park. The algorithms converge well for the more abundant and easily detected of the two species, but some simplification of the spatial model is required for convergence for the second species. We show how these methods lead to maps of estimated relative density which are an improvement over those that would follow from past approaches that ignored spatial dependence. This work also highlights the importance of good survey design for bird species mapping studies. 相似文献
4.
内蒙古赤峰市松山区耕地演变模拟 总被引：1，自引：0，他引：1
[目的]揭示赤峰松山区耕地演变规律,为该区土地利用合理规划管理、生态恢复和经济发展政策的制定提供科学依据。[方法]基于1990,2000,2010年TM遥感影像解译数据,分析研究区耕地动态变化特征,采用GIS中多标准评价(MCE)方法,结合元胞自动机—马尔可夫(CA-Markov)模型,对2020年耕地空间格局变化进行模拟。[结果]耕地的演变空间差异性显著:(1)城郊区由于城镇化速度的加快,大量耕地转化为建设用地。(2)松山区西部石质山区,该地区海拔较高,坡耕地较多,水土流失严重,土壤贫瘠,导致撂荒弃耕严重,同时由于退耕还林政策的实施,耕地在不断减少。(3)松山区东部黄土丘陵台地区,海拔相对较低,地势平坦,适宜于耕地开发,增加的耕地主要源于未利用地和草地。(4)2020年研究区土地利用格局模拟图显示耕地的破碎化程度将有所缓减,开始向规模化发展,同时松山区耕地空间格局稳定性逐渐增强。[结论]该模型模拟结果的精度较高,依据耕地演变趋势,科学合理的利用耕地,制定相应的政策,同时研究结果可为土地资源优化配置奠定基础。 相似文献
5.
流沙河流域土地利用变化研究 总被引：2，自引：0，他引：2
流域土地利用/土地覆被变化是区域土地利用变化研究的重要内容。通过数字化1965年的地形图和对1976年、1988年、2003年三期L andsatM SS/TM/ETM卫星影像的解译得到西双版纳流沙河流域土地利用信息,进而在A rc G IS的支持下,采用土地利用转移矩阵和几种景观指数,结合该区域民族分布和传统习俗对流域土地利用变化进行分析。结果表明:流域的自然条件决定了土地利用的空间分布格局,但民族传统习俗的影响也很大:靠近坝区的山区居民以傣族为主,人口密度较大,森林覆盖率却较高;距离坝区较远的山区,主要是山地民族,人口密度小,但森林覆盖率也小,民族因素对森林以及其他土地利用类型的影响要大于人口因素。政策对土地利用的时间变化影响较大,从1965~2003年,流域的土地利用/土地覆被发生了很大变化,1965年、1976年、1988年和2003年4年中流域的主要土地利用类型都是有林地,但有林地面积在减少,受人类活动影响较大的土地利用类型面积在增加,人类活动对土地利用的干扰增强,土地开发利用强度有增大的趋势。 相似文献
6.
基于2000-2015年河北省土地利用数据,及可能影响河北省林地变化的主要经济指标数据,对河北省林地的空间变化特征及驱动力进行了分析。利用土地利用类型转移矩阵与土地利用动态度模型,对河北省土地利用进行了分析并得出林地的空间变化特征。结合河北省2000-2015年可能影响林地变化的经济指标数据,在R语言中利用msgps程序包实现了Adaptive-Lasso变量选择模型,选取了影响林地面积变化的主要经济因素。模型分析结果显示:2000-2015年,河北省林地面积整体呈增加趋势,林地转入量大于林地输出量,且与草地、耕地之间的相互转化最为突出,与河北省林地变化显著相关的重要解释变量中,年末总人口、农村居民可支配收入和城镇人口与林地面积变化呈正相关性,第一产业、财政收入、财政支出与农村人口数与林地面积变化呈负相关性,其中,农村居民可支配收入与财政收入为主导因素,且河北省的林地变化不仅与国家退耕还林政策相关,也与河北省的独特地理位置相关。该研究为河北省制定并实施林地资源保护与开发利用政策提供决策依据,该方法同时适用于全国其他地区的林地驱动力研究。 相似文献
7.
Secondary forests and exotic tree plantations are rapidly expanding across tropical landscapes, yet we currently have a very poor understanding of the value of these human-dominated forest landscapes for biodiversity conservation. Mist netting, point counts and transect walks were used to compare the bird communities of these habitats and neighboring primary forest in north-east Brazilian Amazonia. The extensive spatial scale of plantations and second-growth in our study area enabled us to implement a robust replicated design, with survey plots approximately two to three orders of magnitude larger than most previous studies of land-use change in the tropics, thus minimising the influence of the surrounding landscape. Species richness was highest in primary forest and lowest in Eucalyptus plantations, and community turnover between habitats was very high whether based upon matrices of relative abundance or species presence-absence data, and for both point count and mist net data. Monthly line-transect censuses conducted over an annual cycle showed an increase in the detection of canopy frugivores and seed predators during the peak of flower and fruit availability in primary forest, but failed to suggest that second-growth or Eucalyptus stands provide suitable foraging habitat at any time of the year. The conservation value of both secondary forest and plantations was low compared to conclusions from previous studies. Our results indicate that while large-scale reforestation of degraded land can increase regional levels of diversity, it is unlikely to conserve most primary forest species, such as understorey insectivores and canopy frugivores. 相似文献
8.
利用遥感与GIS研究区域土地利用变化,揭示其空间变化规律,能够有效监测土地利用变化。本文以重庆山地城市区为研究范围,利用1985—2010年8期Landsat TM遥感数据,对土地利用动态度、土地利用程度的变化特征进行系统分析。结果表明:1985—2010年重庆山地城市总体上呈现耕地、草地、未利用地面积减少,林地、建设用地、水域面积增加的趋势,且各地类变化的程度和过程有所不同;不同土地利用类型的动态度变化呈现出差异性,未利用地和建设用地的动态变化度一直较大,耕地和林地的很小;近26 a来,土地利用程度总体呈增大的趋势,表现出明显的时间阶段性。研究结果对区域土地管理及土地的合理利用具有一定的参考价值。 相似文献
9.
以南京市为研究对象,采用南京市1986年、1996年、2002年、2013年的四期土地利用/覆被数据,运用景观生态学原理,借助ArcGIS软件和Fragstats软件,从土地利用类型结构、变化速度、转化关系和景观格局等方面分析南京市近30年土地利用/覆被和景观格局的时空变化状况及其驱动因素。结果表明:（1）南京市近30 a中土地利用/覆被发生了剧烈变化,耕地在整个研究区起到主导作用,其面积比例均在48%以上,但是其优势度逐渐降低,大量自然景观向人为景观转变是研究区土地利用变化最显著的特征;（2）整体景观类型变化速度都在增大,而草地和其他用地变化最为活跃,林地相对最稳定,土地利用结构处于快速调整阶段;（3）耕地的转出最大,主要转向为居民点及建设用地;（4）景观格局变化明显,破碎化程度越来越高,景观格局趋向复杂化,景观结构不稳定性增加;（5）人口增长、经济发展、区域政策和城市规划等共同推动了研究区景观格局的变化。该研究结果对于南京市的科学规划及可持续发展提供重要参考。 相似文献
10.
Hartwell H. Welsh Jr. Karen L. Pope Clara A. Wheeler 《Biological conservation》2009,142(11):2797-2801
Kroll et al. [Kroll, A.J., Runge, J.P., MacCracken, J.G., 2009. Unreliable amphibian population metrics may obfuscate more than they reveal. Biological Conservation] criticized our recent advocacy for combining readily attainable metrics of population status to gain insight about relationships between terrestrial plethodontid salamanders and forest succession [Welsh, Jr., H.H., Pope, K.L., Wheeler, C.A., 2008. Using multiple metrics to assess the effects of forest succession on population status: a comparative study of two terrestrial salamanders in the US Pacific Northwest. Biological Conservation 141, 1149–1160]. They argue that each of our metrics has the potential to be biased or flawed and, therefore, any inferences so derived are likely to be uncertain and misleading. One of our main goals was to highlight the value of combining multiple quantitative approaches with logic, knowledge of species’ biology and parsimony when interpreting findings, as a means to counter uncertainty that might occur with any single metric. We applied a sampling design that minimizes the chance of bias in detections and counts, included multiple statistical methods to test relationships, and incorporated past research and species’ biology when interpreting findings. We disagree with Kroll et al. [Kroll, A.J., Runge, J.P., MacCracken, J.G., 2009. Unreliable amphibian population metrics may obfuscate more than they reveal. Biological Conservation] that the potential biases associated with the individual metrics mean that the inferences from the study are too uncertain to be useful by managers. We examined metrics that are more informative than simple site occupancy, including relative abundance, life stage distributions, and body condition, to inform our knowledge of population status. Combining metrics allows us to use readily attainable data to yield deeper insights into population structure and related spatial aspects. We agree on the value of having the most detailed and accurate data possible, but do not believe this standard should limit one to conducting only intensive experimental studies to provide detailed information on vital rates of terrestrial salamanders. The controlled experiment approach is extremely difficult and would be considerably less feasible than using population metrics to assess the status of plethodontid salamanders on forest landscapes at scales relevant to land management in the Pacific Northwest. 相似文献
11.
研究经济快速发展的沿海地区土地利用结构的变化并预测其未来发展趋势,可以为区域土地合理利用与配置提供参考。以青岛市为研究区,采用Logistic-CA-Markov耦合模型,基于2000年、2011年土地利用解译数据,结合DEM、人口、GDP、距离等因素模拟出2011年土地利用数据,与2011年解译数据对比,得到模拟精度为94.27%,说明模型拟合精度较高,接着对2022年、2033年土地利用空间格局进行了预测。Logistic-CA-Markov模型模拟的2011—2022年土地利用类型将保持2000—2011年的变化趋势,表现在耕地、水域、未利用土地面积减少,林地、草地以及城乡、工矿、居民用地面积增加,2022—2033年城乡、工矿、居民用地面积仍然增加,但是增加速率明显小于2011—2022年。研究结果表明,Logistic-CA-Markov耦合模型具有较高的模拟精度,可以应用于模拟多类土地利用类型之间的演变。该研究可为青岛市的土地规划、管理和决策提供依据,同时对保护和改善生态环境具有现实的指导意义。 相似文献
12.
快速城镇化背景下,推进土地利用高质量转型是实现区域可持续协同发展的重要路径。该研究基于土地利用主导功能,运用综合指数法、耦合协调度模型和时空地理加权回归模型（geographically and temporally weighted regression, GTWR）等方法,分析了环鄱阳湖城市群土地利用功能转型的时空演变特征、耦合协调水平及其驱动机制。结果表明：1）2000—2020年,环鄱阳湖城市群土地利用功能指数从0.20上升到0.55,持续优化提升,但总体上处于中低水平,土地利用功能水平表现为阶段性的变化特征;土地利用功能指数逐渐呈现出中西高、东部低的空间格局。2）生产-生活-生态功能及生产-生活功能的协调度指数持续上升,其余耦合度及协调度指数均呈波动发展的趋势,耦合协调度指数呈现中部和西南部高、东北和西北部低的空间分布格局;以低质量转型为主,平均占比约为50%,功能转型质量有所提升,中西部区县的土地利用功能转型质量要明显优于北部和东部区县。3）不同影响因子的驱动作用存在显著的空间差异。人口密度和城镇化水平的正向驱动作用持续增强,二三产业占比的负向驱动作用增强,人均GDP、人均固定资产投资和人均粮食产量的影响力趋于减弱。应根据各区县土地利用功能的转型阶段,实行差别化的发展政策,补齐区县发展短板,提升功能系统间的耦合协调度。研究结果可为提高区域用地效率,促进土地利用多功能协同发展提供参考和决策依据。 相似文献
13.
珠江三角洲土地利用分形特征及其影响机制 总被引：5，自引：1，他引：4
该文以遥感影像解译数据为基础,在分析1990、2000和2006年3个时期珠江三角洲土地利用数量变化的基础上,应用分形维数模型计算出珠江三角洲各土地利用类型的分形维数和稳定性指数,对其土地利用空间结构及其区域差异进行了深入研究,应用灰色关联分析法探讨了分形特征的影响机制。研究表明,珠江三角洲建设用地面积快速扩张,耕地、林地面积迅速减少,土地利用空间结构由复杂趋向简单,稳定性不断增强,水域空间结构最复杂,未利用土地最简单,水田、城镇用地、未利用土地的空间结构趋向复杂,其余地类的空间结构趋向简单。各市（区、县）分形特征差异明显,分形变化各不相同。分形特征主要受图斑自身几何性质的影响,人口因素影响在减弱,三大产业中以第一产业影响较大。 相似文献
14.
WU Qian LI Qing-Liang GAO Jin-Bo LIN Qiao-Ying XU Qiu-Fang P. M. GROFFMAN YU Shen 《土壤圈》2017,27(1):147-154
Integrating land use type and other geographic information within spatial interpolation has been proposed as a solution to improve the performance and accuracy of soil nutrient mapping at the regional scale.This study developed a non-algorithm approach,i.e.,applying inverse distance weighting (IDW) and ordinary kriging (OK),to individual land use types rather than to the whole watershed,to determine if this improved the performance in mapping soil total C (TC),total N (TN),and total P (TP) in a 200-km2 urbanizing watershed in Southeast China.Four land use types were identified by visual interpretation as forest land,agricultural land,green land,and urban land.One hundred and fifty soil samples (0 10 cm) were taken according to land use type and patch size.Results showed that the non-algorithm approach,interpolation based on individual land use types,substantially improved the performance of IDW and OK for mapping TC,TN,and TP in the watershed.Root mean square errors were reduced by 3.9％ for TC,10.7％ for TN,and 25.9％ for TP by the application of IDW,while the improvements by OK were slightly lower as 0.9％ for TC,7.7％ for TN,and 18.1％ for TP.Interpolations based on individual land use types visually improved depiction of spatial patterns for TC,TN,and TP in the watershed relative to interpolations by the whole watershed.Substantial improvements might be expected with denser sampling points.We suggest that this non-algorithm approach might provide an alternative to algorithm-based approaches to depict watershed-scale nutrient patterns. 相似文献
15.
不同土地利用变化情景下的洪汝河流域水文响应 总被引：1，自引：0，他引：1
[目的]研究洪汝河流域土地利用变化对水文过程的影响,为当地水资源的合理规划和利用提供依据和参考。[方法]本研究以土壤水体评价模型(soil and water assessment tool,SWAT)为基础,通过设计多种土地利用情景模式模拟洪汝河流域水文情景,首先利用数字高程模型(digital elevation model,DEM),土地利用数据、土壤数据以及日气象数据建立模型;其次选用2006—2008年的水文观测数据进行模型率定,并进行敏感性和不确定性分析;最后,设置4种土地利用情景模式进行水文模拟。[结果]退耕还林情景下径流减少4.23%;而在耕地增加,城镇用地增加和以城镇用地、林地草地增加为主的复杂土地利用变化这3种情景下,径流分别增加3.01%,4.91%和1.50%。[结论]退耕还林增加了可涵养水源的森林,使得径流减少,而增加耕地开垦或城市建设用地则会增加地表径流。 相似文献
16.
[目的] 从地形和社会经济两个因素出发探讨广东省土地覆被变化的时空差异及成因，为土地资源的可持续利用提供依据。[方法] 基于1992-2015年间广东省土地覆被数据，使用土地利用动态度、土地利用转移矩阵、灰色关联分析等方法量化土地覆被变化的时空特征与差异。[结果] 广东省土地覆被变化以2000年为节点可分为前期（1992-2000年）和后期（2000-2015年）两个阶段。前期耕地面积显著增加，建筑用地面积增速缓慢；后期耕地面积减小，建筑用地面积扩张迅速。地形因素造成土地覆被变化存在空间差异性。在高程低，坡度缓的区域土地覆被变化主要是耕地转化为建筑用地，而在坡度中等区域主要是林地转为耕地。社会经济因素造成土地覆被变化呈现较明显时间差异性，多种因子驱动广东省土地覆被发生变化。但对于不同的土地覆被类型，驱动因子前后期的关联度大小不同，土地覆被发生变化是多种因子驱动叠加的结果。[结论] 地形因素会造成土地覆被变化的空间差异，而社会经济因素导致土地覆被变化的时间差异。 相似文献
17.
[目的]分析大兴安岭地区盘古河流域土地利用变化情况,研究流域径流对不同土地利用情景的响应,为合理规划土地利用提供依据。[方法]利用盘古河流域1987,2000和2011年3期土地利用数据和1988—2012年的水文气象资料,结合SWAT(soil and water assessment tool)模型,分析盘古河流域土地利用变化的径流响应。[结果]1987—2011年盘古河流域主要土地利用变化为裸地向林地、草地转化,林地面积增加,裸地面积减少;汛期径流量占年总径流量的比例随着林地的增加而减少;林地的增加使得多年平均年径流量、汛期径流量和最大月经流量均呈减少趋势。[结论]SWAT模型能够较好地模拟盘古河流域的月流量过程;流域径流随着林地面积的增加而减少。 相似文献
18.
为揭示边境地区土地利用转型对生态服务功能的影响,推动区域生态环境与社会经济高质量发展。基于广西边境地区2000年、2010年、2018年3期土地利用遥感监测数据,识别18年间土地利用转型和生态系统服务价值的动态演变过程,结合改进的交叉敏感性系数探讨了广西边境地区生态系统服务价值对土地利用转型的敏感性程度。结果表明:(1)2000—2018年广西边境地区土地转型前期平缓,后期剧烈,耕地向建设用地、水域的转移是主要的转型驱动因素;(2)2000—2018年ESV呈现出先增后减的态势,地均ESV高值主要集中于防城区、宁明县南部以及那坡县南部生态环境本底优越的一带,地均ESV低值出现在宁明县北部、龙州县、大新县以及靖西市的中心城区生态系统较为薄弱的岩溶地区;(3)耕地、林地、水域与其他地类相互转型对生态系统服务功能影响较为敏感,其中最敏感的是林地与建设用地的转型,草地、未利用地与其他地类的转型缺乏敏感性。(4)生态敏感性空间演化分异特征显著,耕地与建设用地高生态敏感性重点分布在东兴市、宁明县、龙州县、靖西市,林地与建设用地高生态敏感区主要分布在防城区和东兴市主城区、凭祥市以及靖西市北部等重要的贸易出口通道。研究结果可为优化边境国土空间格局,实现生态服务功能的提升提供科学指引。 相似文献
19.
Huiyan Sang Alan E. Gelfand 《Journal of Agricultural, Biological & Environmental Statistics》2010,15(1):49-65
We propose a hierarchical modeling approach for explaining a collection of point-referenced extreme values. In particular,
annual maxima over space and time are assumed to follow generalized extreme value (GEV) distributions, with parameters μ, σ, and ξ specified in the latent stage to reflect underlying spatio-temporal structure. The novelty here is that we relax the conditionally
independence assumption in the first stage of the hierarchial model, an assumption which has been adopted in previous work.
This assumption implies that realizations of the the surface of spatial maxima will be everywhere discontinuous. For many
phenomena including, e.g., temperature and precipitation, this behavior is inappropriate. Instead, we offer a spatial process
model for extreme values that provides mean square continuous realizations, where the behavior of the surface is driven by
the spatial dependence which is unexplained under the latent spatio-temporal specification for the GEV parameters. In this
sense, the first stage smoothing is viewed as fine scale or short range smoothing while the larger scale smoothing will be
captured in the second stage of the modeling. In addition, as would be desired, we are able to implement spatial interpolation
for extreme values based on this model. A simulation study and a study on actual annual maximum rainfall for a region in South
Africa are used to illustrate the performance of the model. 相似文献
20.
A key element in the efficient allocation of scarce resources for conservation is the identification of areas of high biological value and high threat. Habitat loss and human population density have proved useful predictors of spatial variation in the current threat status of species albeit at coarse spatial resolution. We present a global analysis, intersecting Endemic Bird Areas (EBAs), to which restricted-range bird species are endemic, with fine-scale data of agricultural extent and human population density and test: (a) how well variation in land use mapped at 0.5° × 0.5° resolution predicts spatial variation in threat status of species and (b) how the predictive power compares with that of human population density mapped at the same resolution. Variation among EBAs in the proportion of restricted-range species that are threatened can be predicted by both the proportion of land used for agriculture and human population density. Agricultural land use was a better predictor of threat status than human population. Further, the average levels of threat attributable to agriculture were better predicted by land use than human population density, whereas threats due to causes other than agriculture were equally well predicted by land use and human population density. We fitted quantitative empirical models to describe these relationships. These results could be used, together with spatially explicit future scenarios of land use change, to project the geographical distribution and magnitude of future threats to birds at global and regional scales. 相似文献