云南纵向岭谷区道路网络对生态系统影响的阈值分析

云南纵向岭谷区由于受到人类活动,尤其是道路网络的影响,使得该地区生态系统退化日益严重.通过云南纵向岭谷区路网密度与生态系统转换(1980～2000年期间)的多尺度空间相关分析,研究了路网的对生态系统的影响及其阈值.研究结果表明,路网是导致有林地向疏林地、有林地向中覆盖度草地、灌木林地向疏林地转变的主要影响因子.路网导致有林地向疏林地转变的路网密度均值为0.8381～0.8800 km/km2,导致有林地向中覆盖度草地转变的路网密度均值为0.6984～0.8124 km/km2,导致灌木林地向疏林地转变的路网密度均值为1.2770～3.6426 km/km2.随着尺度的增大,路网密度的变化不显著.路网影响阈值的研究,开始从定量的角度探索道路网络对生态系统的影响,对公路建设、规划和管理具有一定的理论和应用价值.     

多尺度生态系统服务的权衡关系及其对景观配置的响应——以湖北省为例

多种生态系统服务相互关系及其对景观配置响应的多尺度分析一直是生态系统服务研究的热点问题,对于厘清生态系统服务尺度效应和实现区域分级管理具有重要的意义。以湖北省为研究区域,采用遥感、土地利用类型、水文、气象、土壤等多元数据,从5 km×5 km、10 km×10 km、15 km×15 km、20 km×20 km、25 km×25 km、县域和市域等7个递增尺度分析4种生态系统服务(水源供给、碳固持、粮食生产、水质净化)对景观配置的响应关系。结果表明：(1)4种生态系统服务的空间分布具有较强的异质性,粮食生产服务的高值区与水质净化服务的低值区主要分布于湖北省中部和东部的耕地集中区域,碳固持与水源供给呈现相反的空间特征。(2)生态系统服务权衡关系的作用强度随尺度增加而减弱,而协同关系呈增加趋势;同时服务间相互作用强度的变化大于作用方向的变化。(3)景观配置对生态系统服务的影响程度在县域和市域尺度上大于格网尺度。结果反映了受尺度变化中“削峰填谷”过程的影响,景观配置对生态系统服务影响的大小和正负效应具有尺度差异性。研究结果可为区域生态系统服务分级管理和景观格局调控提供科学参考。     

纵向岭谷区植被景观多样性的空间格局

基于中国1∶100万植被类型数据,采用GIS空间分析方法,分析了纵向岭谷区主要植被景观多样性指数的空间格局及其与环境因子之间的关系.结果表明:研究纵向岭谷区植被景观多样性的理想粒度是2000m;纵向岭谷区植被景观多样性指数的空间格局具有明显的区域分异特征,表现为南北方向延伸、东西方向分异的"通道-阻隔"空间格局;植被景观多样性与环境因子的相关性较好,环境因子在空间上的分异格局是影响植被景观多样性指数在空间格局上变化的主要因素.纵向岭谷特殊地形的"通道-阻隔"作用对该区的水热空间分布进行了再分配,是该区植被景观多样性的特殊空间格局的主要成因.     

江苏省路网密度与聚落占地率的关系

基于2000年江苏省1∶1万地形图数据,应用邻域分析方法,对江苏省15个县(或县级市)的道路与聚落在5、10、15及20 km 4个尺度上的空间分布特征及二者在16个尺度组合下的关联强度进行了比较.结果表明:道路是异质性较低的景观要素类型,而聚落是异质性较高的景观要素类型;道路与聚落的空间异质性水平均随着观测尺度的增大而降低,但前者的异质性水平随尺度增加而降低的程度不如后者明显;路网密度较大或聚落占地率较高的地区,道路及聚落分布的空间异质性均分别趋于下降;在16个尺度组合中,20 km尺度路网密度与5 km尺度聚落占地率的关联程度最高;在上述尺度组合下,路网密度随聚落占地率的增大呈阶梯式增长,路网密度的增长表现出非连续性特征;由于这两种不同景观要素类型往往具有不同的尺度依赖特征,有必要比较多种尺度组合下二者的相关程度,并选择合适的尺度组合来研究景观要素间的相关关系.     

基于小波变换的NDVI与地形因子多尺度空间相关分析

以西藏高原生态系统的NDVI（Normalized Difference Vegetation Index）及其地形影响因子为分析对象,使用小波变换揭示了其多尺度空间格局。通过小波方差尺度图可以辨识出,在研究区域内NDVI及其地形因子存在着4、12km和25km等多尺度变异格局。小波多尺度相关分析是对普通相关的一种拓展,使用小波系数分尺度计算了NDVI及其影响因素的相关系数,并与普通相关进行了比较。结果表明,4种地形因子（海拔高度、坡度、坡向和CTI）不论是正相关还是负相关,在较小尺度上与NDVI的相关系数都比较小,一般情况是尺度增大,相关性增大。这反映了地形因子作为大的宏观制约因素对NDVI起作用。实践证明,小波分析对于揭示自然要素的多尺度空间结构和各向异性是一种强有力的工具。     

甘肃永登县土地利用景观格局的空间尺度效应

依据“斑块-廊道-基质”模式,研究了甘肃省兰州市永登县景观格局的空间尺度效应.结果表明:草地为整个研究区景观结构的基质;廊道包括道路和河流;其余景观组分(耕地、林地、园地,住宅用地、工矿用地、公共管理与服务用地和其他土地)均为斑块.斑块类型水平指数与景观水平指数均表现出明显的空间幅度依赖性.不同景观组分的斑块类型指数的尺度效应在不同幅度区间存在差异性,景观水平指数的尺度效应在不同幅度区间也存在差异性.在1～20 km幅度区间,尺度效应的组分类型、指标类型之间差异最为明显;在21～90 km幅度区间,尺度效应的组分类型、指标类型之间差异较小;在>90 km幅度后,尺度效应消失.90 km×90 km为研究景观格局尺度依赖性的有效幅度.     

生态系统受威胁等级的评估标准和方法

生态系统受威胁等级评估是认识生物多样性丧失的重要手段.在2008年的第四次世界自然保护大会上,国际自然保护联盟(IUCN)成立专门工作组,着手建立类似于物种灭绝风险的定量评估方法,对生态系统受威胁等级进行评估.最终的目标是在局地、区域和全球尺度上确定生态系统的受威胁等级,建立生态系统红色名录.在制定生物多样性保护策略时,生态系统红色名录与物种红色名录可作为互补.目前,生态系统受威胁等级评估方案的评估依据包括4类:生态系统分布或生态系统功能短期衰退;生态系统分布或生态系统功能长期衰退;生态系统当前的分布狭窄、同时生态系统分布或生态系统功能衰退;生态系统当前的分布极狭窄.应用Rodríguez等(2011)建立的评估标准,基于文献记载的中国辽河三角洲4个生态系统1988年和2006年的面积,我们详细介绍了生态系统受威胁等级的评估过程.目前的评估方法面临挑战,生态系统分布范围和占有面积的估计应基于合理的空间尺度,同时还需建立合理的方法定量描述生态系统功能的变化.生态系统受威胁等级评估方案将提交2012年召开的世界自然保护大会讨论.     

北京城区道路系统路网空间特征及其与LST和NDVI的相关性

城市道路系统是人类活动最为频繁的场所之一,研究路网空间特征与相关环境指标的关系,可为定量分析城市建设过程对城市生态环境的影响以及为城市基础设施规划管理提供方法。对北京市五环内各级道路抽样调查及面向对象的高分辨率遥感影像识别,建立道路空间信息数据库,运用TM影像反演获得地表温度(LST)及归一化植被指数(NDVI),研究4种不同分析网格下城市路网特征与两者的空间相关性。结果表明,在较大分析网格下(4×4),路网空间指标与LST mean及NDVI mean相关性显著;中等网格下,除LST与NDVI的平均值外,路网空间指标还可与两者最小值建立相关性;在较小窗口下(32×32),除平均值与最小值,还可建立特定道路指标与LST max及NDVI max的联系;各路网指标中,单位面积道路总长与LST及NDVI相关性最强;加权道路结点数在8×8和32×32网格分析中,与NDVI的相关性高于该指标未加权值,而结点指标均不适合与LST max建立联系;在各分析网格下,4项道路指标均与NDVI mean呈极显著负相关,表明道路绿地建设规模还不足以对NDVI的强度及分布产生较大影响。     

重庆市道路网络影响景观破碎化的阈值分析

路网的不断扩张是导致景观破碎化的一个重要因素, 因此, 研究路网密度影响景观破碎化的阈值具有重要意义。通过KDE 法确定反映路网密度分布的最佳带宽, 以此带宽分析重庆市路网空间格局, 进一步利用缓冲区法得到路网影响景观破碎化的最大范围, 在该范围内计算路网叠加前后的景观指数变化率, 分析影响景观破碎化的路网密度阈值。结果表明: 3 km 的带宽很好的反映了重庆市路网密度分布; 重庆市路网密度空间分布不均匀, 路网发达区主要位于中部、西北部和西南部, 路网稀疏区主要位于东北部和东南部; 路网对景观破碎化的最大影响范围为1000 m; 道路密度等级7 级是路网密度影响斑块密度和平均斑块面积的阈值, 而道路密度等级8 级是路网密度影响聚集度指数的阈值。     

基于四象限模型的生态系统服务与人类活动强度关联性分析--以皖南国际旅游文化示范区为例

运用空间热点分析定量分析了生态系统服务在不同尺度上的空间分异特征,基于四象限模型对生态质量进行评价,并采用地理探测器探讨影响其空间分异的主要驱动因素。结果表明:(1)生态系统服务价值(Ecosystem Service Value,ESV)存在显著的空间异质性,分布格局呈现空间自相关性,冷热点分布具有明显尺度效应。(2)示范区人类活动强度与ESV耦合程度基本协调一致,生态质量总体状况较好。人类活动强度与ESV耦合程度因研究尺度不同而存在一定差异。(3)各探测因子的解释力在县域和乡镇尺度上存在显著差异,社会经济驱动因素在县域尺度上解释力大于乡镇尺度。各驱动因子之间存在明显的协同增强效应,双因子交互作用增强了对ESV空间分异的解释力。     

道路生态学研究进展

“道路生态学”是当代景观生态学的最新研究领域。重点探讨道路生态学和生态道路网的研究进展。从景观生态学的点效应、廊道效应和边际效应出发 ,引入景观生态网络的概念 ,即由点、线、网按照一定等级结构、功能分工和空间秩序组合成的生态网络体系 ,其中道路网和水网是最主要的表现形态。根据网络理论构造网络结构影响度模型 ,在 GIS和 RS的支持下 ,通过对北京局部地区道路网动态模拟的分析表明 ,道路网对其他景观的影响是通过点效应、廊道效应、点 -廊道 -网络叠加效应共同作用的结果 ,这种影响与道路网络密度和道路影响带的范围成正比。因此 ,为了最大限度减少道路网对自然生态系统的干扰与破环 ,提出生态道路网络建设的 8点建议     

基于网络K函数的西双版纳人工林空间格局及动态

区域植被格局的分布特征受诸多要素影响,但其空间格局和动态具有一定规律或自相关性,道路网络作为景观中显著的人工线性要素,在很大程度上影响着区域的植被格局特征,特别是人工植被的分布特征.运用网络K函数,分析了道路网络和人工林空间格局分布的相互关系,并且用二元网络K函数研究了人工林扩展对针叶林和阔叶林的影响.结果表明:人工林在1970-2000年间种群分布格局有非常明显的变化,特别是从1990到2000年,种群面积不断扩大,主要从北部地区扩展到西北和东南地区.1970-1990年人工林扩展主要集中在低海拔的道路网络附近,沿道路网络呈现明显的集聚分布,公路效应明显.但后期逐渐向距公路较远、海拔较高的地区扩展,到2000年在大尺度下人工林斑块呈显著随机分布.同时,人工林面积的增长对针叶林影响显著,对阔叶林有影响但是并不显著.二元网络K函数表明,在1970到1990年人工林与针叶林沿道路网络在小尺度为负关联,在局部地区存在着竞争,但在大尺度上对环境条件的要求具有一致性为正关联.到2000年,在大尺度上人工林与针叶林的种群分布格局呈显著负相关,人工林面积的不断扩展导致了针叶林面积的下降.     

Environmental and land use determinants of grassland patch diversity in the western and eastern Alps under agro-pastoral abandonment

Agro-pastoral decline in European mountain areas has recently caused changes to traditional landscapes with negative consequences on semi-natural grassland conservation and the associated biodiversity and ecosystem services. In the Italian Alps, grassland patches enclosed in a forest matrix are progressively disappearing. Two alpine valleys (Pesio and Pejo), having similar land-use history, were chosen as representative of management conditions of western and eastern Italian Alps, respectively. This study aims at interpreting the effect of abandonment on grassland patch plant diversity, considering land cover changes of the last 60 years, and assessing the role of ecological, topographic, management and landscape configuration on current grassland species richness. The total area of grassland patches has declined by 54 and 91 % at Pesio and at Pejo, respectively. Actual grassland patch species richness was mostly influenced by ecological factors, such as quantity of light, soil moisture and reaction, then by topographic features, especially slope, and finally by management intensity. Landscape factors exerted a slightly significant effect on plant diversity. In the two valleys, differences on management practices were detected. Even though in the western valley the conservation of several grazing activities contributed to slow down the process of patch reduction, many species-rich grasslands were generally under-grazed. Conversely, in the eastern valley, despite a denser road network, the stronger decline of grassland patch extension was linked to the hay making decline. At the same time, overuse of grassland patches near farms reduced plant species richness. As a conclusion, plant species richness was weakly related to the area of grassland patches and current and historical landscape configuration were of relatively lower importance than ecological, topographic and management factors, when evaluated at patch-level.     

Vegetation,herbivores and fires in savanna ecosystems: A network perspective

The dynamics of savanna ecosystems depends on the interplay between multiple factors such as grazing, browsing, fires, rainfall regime and interactions between grass and woody vegetation. In most modelling applications this interplay may not be fully understood because some of these drivers enter the models as dynamically independent factors. In this paper we consider such factors as dynamic variables. To analyze their interplay we focus on the structure of the interactive network of variables and exploit the properties of signed digraphs using the algorithm of Loop Analysis. Qualitative signed digraphs for the savanna ecosystem are developed and their predictions used to interpret patterns of abundance observed in case studies selected from the literature. The outcomes of this exercise unveil that: 1) the structure of the interactions is appropriate locus for the explanation of patterns observed in savannas; 2) signed digraph can help disentangling causative mechanisms by linking correlation patterns, source of change and network structure. This study highlights that central to the understanding of savanna dynamics is our ability to diagram the important relationships and understand how they interrelate with sources of variations to cause ecosystem change.     

大兴安岭林区道路网络对景观格局的影响

在明确大兴安岭呼中林业局道路网络系统组成特征的基础上,利用主成分分析法,将林业局内17个林场作为分析单元,以该林业局1989年景观为例,对有、无道路情况下的景观格局分别进行定量分析,探讨了道路对森林景观格局的影响.结果表明：呼中林业局内包括运材主、支路在内的常年运材路密度为2.3 m·hm^-2,在各个林场内分布均匀,基本沿着河流水系深入到各个采伐区.道路的出现使景观水平上的森林格局发生了显著变化：所有林场中,平均斑块面积减少、数量增多、斑块间距离增大,均表现出不同程度的破碎化,但破碎化程度与道路密度之间没有显著的相关性;道路网络对景观破碎程度的影响比对空间聚合程度的影响更强烈.     

Impact of road construction on giant panda’s habitat and its carrying capacity in Qinling Mountains

The Qinling giant panda (Ailuropoda melanoleuca) is an endangered endemic species to China. Despite ongoing efforts to ensure its conservation, concerns about maintaining its populations persist. We used GIS fed with data on land use including road network of 2001, third national giant panda survey, and a digital elevation model (DEM) to assess the impact of road construction on giant panda habitat, and estimate the carrying capacity of the Qinling Mountain area. We assessed habitat suitability with a mechanistic model, and conducted correlation analysis to evaluate relationship between the extent of giant panda habitat and amount of sites occupied by pandas within of 5 km × 5 km grid. We also estimated the carrying capacity of the Qinling Mountainous Area.
Our results revealed a significant correlation (R² = 0.447, P < 0.01) between the number of sites with signs left by giant panda and the extent of habitat within of 5 km × 5 km grid. The minimum habitat area that can support one panda was 10 km². Before the road network construction, the area of habitat suitable for the panda amounted about 1561 km² and that of marginally suitable habitat about 1499 km². The corresponding carrying capacity represented about 240 individuals. After the road network construction, the suitable habitat area was reduced by nearly 30% to 1093 km². Marginally suitable habitat and unsuitable habitat have both increased by 17% and 1%, respectively. As a result, the potential population size which the habitat could support was reduced to 217 individuals. The study results also suggested that most impacts on habitat from road construction took place in the high elevation areas above 1500 m. However, regarding the impact on the giant panda habitat, road networks developed much more inside the current nature reserves than outside of them.     

Impact of road construction on giant panda’s habitat and its carrying capacity in Qinling Mountains

The Qinling giant panda (Ailuropoda melanoleuca) is an endangered endemic species to China. Despite ongoing efforts to ensure its conservation, concerns about maintaining its populations persist. We used GIS fed with data on land use including road network of 2001, third national giant panda survey, and a digital elevation model (DEM) to assess the impact of road construction on giant panda habitat, and estimate the carrying capacity of the Qinling Mountain area. We assessed habitat suitability with a mechanistic model, and conducted correlation analysis to evaluate relationship between the extent of giant panda habitat and amount of sites occupied by pandas within of 5 km × 5 km grid. We also estimated the carrying capacity of the Qinling Mountainous Area.
Our results revealed a significant correlation (R² = 0.447, P < 0.01) between the number of sites with signs left by giant panda and the extent of habitat within of 5 km × 5 km grid. The minimum habitat area that can support one panda was 10 km². Before the road network construction, the area of habitat suitable for the panda amounted about 1561 km² and that of marginally suitable habitat about 1499 km². The corresponding carrying capacity represented about 240 individuals. After the road network construction, the suitable habitat area was reduced by nearly 30% to 1093 km². Marginally suitable habitat and unsuitable habitat have both increased by 17% and 1%, respectively. As a result, the potential population size which the habitat could support was reduced to 217 individuals. The study results also suggested that most impacts on habitat from road construction took place in the high elevation areas above 1500 m. However, regarding the impact on the giant panda habitat, road networks developed much more inside the current nature reserves than outside of them.     

Road networks predict human influence on Amazonian bird communities

Road building can lead to significant deleterious impacts on biodiversity, varying from direct road-kill mortality and direct habitat loss associated with road construction, to more subtle indirect impacts from edge effects and fragmentation. However, little work has been done to evaluate the specific effects of road networks and biodiversity loss beyond the more generalized effects of habitat loss. Here, we compared forest bird species richness and composition in the municipalities of Santarém and Belterra in Pará state, eastern Brazilian Amazon, with a road network metric called ‘roadless volume (RV)’ at the scale of small hydrological catchments (averaging 3721 ha). We found a significant positive relationship between RV and both forest bird richness and the average number of unique species (species represented by a single record) recorded at each site. Forest bird community composition was also significantly affected by RV. Moreover, there was no significant correlation between RV and forest cover, suggesting that road networks may impact biodiversity independently of changes in forest cover. However, variance partitioning analysis indicated that RV has partially independent and therefore additive effects, suggesting that RV and forest cover are best used in a complementary manner to investigate changes in biodiversity. Road impacts on avian species richness and composition independent of habitat loss may result from road-dependent habitat disturbance and fragmentation effects that are not captured by total percentage habitat cover, such as selective logging, fire, hunting, traffic disturbance, edge effects and road-induced fragmentation.     

道路对三江源国家公园黄河源园区藏野驴和藏原羚种群数量及其栖息地的影响

为探究道路对三江源国家公园黄河源园区藏野驴(Equus kiang)和藏原羚(Procapra picticaudata)种群数量及其栖息地的影响,于2020年冷季采用截线取样法在黄河源园区进行实地调查.通过设置4种不同等级的道路情景,使用MaxEnt模型评价藏野驴和藏原羚的生境适宜性,模拟了不同等级道路变量情景下两种...