基于多时相Landsat TM影像的汶川地震灾区河岸带植被覆盖动态监测——以岷江河谷映秀-汶川段为例

基于混合像元分解方法,利用Landsat TM卫星遥感数据监测了岷江上游干旱河谷区映秀\汶川段河岸带植被在汶川地震前后的植被覆盖动态变化,并结合高程、坡度及坡向数据,分析了植被受损及地震3a后植被恢复的空间分布特征。结果表明,地震造成研究区河岸带植被的受损总面积为2736.61hm²,且集中分布在海拔1100-1700m,坡度25-55°之间以及东、东南和西坡;地震3年后,受损植被与震前相比,共恢复了56.20%。     

2006-2016年岷江上游植被覆盖度时空变化及驱动力

基于MODIS NDVI遥感数据,采用像元二分模型估算岷江上游植被覆盖度,运用一元线性回归分析和稳定性分析方法,研究2006-2016年岷江上游植被覆盖度时空变化格局及稳定性,并分段讨论2008年"5.12汶川地震"对岷江上游植被的破坏程度以及震后植被恢复情况,利用地理探测器模型对岷江上游植被覆盖度影响因子及影响力进行探测,分析岷江上游植被覆盖度变化驱动力。结果表明：（1）2006-2016年岷江上游植被覆盖整体状况良好,植被覆盖总体情况较为稳定,多年平均植被覆盖度为0.79,植被覆盖度大于0.8的区域占整个岷江上游地区面积的69%。（2）2008年"5.12汶川地震"给整个岷江上游植被造成了严重的破坏,植被覆盖度退化区域面积为14013.41 km²,占整个岷江上游面积的57%,2008-2016年岷江上游植被恢复状况良好,植被覆盖度改善区域面积为17390.69 km²,占整个岷江上游面积的71%,岷江上游植被覆盖度已经超过震前水平。（3）岷江上游植被覆盖度主要受海拔、气温、土壤类型、降水4个因子的影响,其解释力均在40%以上;地貌类型、植被类型的解释力在20%-40%之间;坡度、坡向的解释力均小于1%。     

基于多时相Landsat5/8影像的岷江汶川-都江堰段植被覆盖动态监测

植被覆盖度是衡量地表植被状况和指示生态环境变化的一个重要指标。基于像元二分模型,利用Landsat5/8遥感影像和DEM数据,对岷江汶川-都江堰段植被覆盖动态变化进行了监测,并结合高程、坡度和坡向数据,分析了汶川地震前后植被受损与恢复的空间动态格局变化。研究表明:植被覆盖总体良好,大部分区域的植被覆盖度均在中、高度以上,空间格局上呈现由汶川县东部、都江堰市西北部的龙门山区向两侧减少的总体趋势;地震造成植被受损面积达63808.7 hm~2,且集中分布于海拔567—4331 m、坡度26—51°的范围以及东坡、北坡、南坡和西坡;震后5a,植被恢复面积17786.47 hm~2,主要分布在海拔576—2180 m与3256—3793 m、坡度小于9°和26—51°以及东坡、东南坡和和南坡;高程和坡度对植被损毁与恢复的影响明显高于坡向。     

基于用地适宜性评价的森林公园景点选址

基于DEM,利用GIS空间分析功能,选取坡度、坡向、地形起伏度、相对现有游道距离和相对现有景点距离等5个成本数据指标,分别对抚顺市新宾猴石国家森林公园用地进行适宜性评价,并构建了综合适宜性评价模型,进而将研究区划分为4个等级适宜性的开发建设区域。综合适宜性评价结果表明,Ⅰ等和Ⅱ等适宜开发区的面积均较大,二者共计占研究区总面积的89.7%,尤其是Ⅱ等适宜区的面积达到664.7 hm²,占研究区总面积的1/2以上,表明研究区大部分地区都可作为景区选址的开发建设用地;Ⅲ等适宜区的面积为126.3 hm²,约占总面积的9.7%;Ⅳ等适宜区的面积最小,为7.3 hm²,仅占总面积的0.6%。     

应急输水工程对塔里木河下游地区植被覆盖度的影响

基于塔里木河下游地区1999年TM、2002年ETM和2004年ASTER遥感影像及其基础背景数据，对应急输水工程前后研究区植被覆盖度和土地沙漠化的动态变化进行了研究.结果表明：随着应急输水工程的实施，塔河下游地区中、高植被覆盖度的面积逐年增加，分别由1999年的 7 447.16、17 146.80 hm²增加至2004年的9 129.16、26 236.61 hm²，低、劣植被覆盖度面积分别减少了9 989.10和782.71 hm²；1999—2004年间，研究区沙漠化总面积由506 258.06 hm²减少至498 043.93 hm²，呈逐年缩小趋势.研究期间，部分沙漠化地区出现了较为明显的逆转，生态环境趋于好转，应急输水工程对塔河下游生态环境的改善起到了重要作用.     

中国主要灌丛植被碳储量

 在广泛收集资料的基础上,利用植被平均碳密度方法,估算了我国6种主要灌丛植被的碳储量,并分析了其区域分布特征。主要结果如下：1) 6种灌丛植被总面积为15 462.64 ×10⁴ hm²,总碳储量为1.68±0.12 Pg C(1 Pg=10¹⁵g),灌丛植被平均碳密度为10.88±0.77 Mg C•hm^-2(1 Mg=10⁶ g),不同植被类型差异较大,在5.92～17Mg C•hm^-2之间波动。2) 从区域分布来看,西南3省(云南、贵州、四川)既是我国灌丛主要的分布地区之一,分布面积占6种灌丛总面积的23.5%,又是我国灌丛碳储量的主要储库,碳储量占整个6种灌丛碳储量的1/3（32.6%）,适宜的水热条件决定了该地区的植被平均碳密度要高于全国平均水平。3) 与我国森林和草地的植被碳储量相比,这些灌丛碳储量相当于我国森林和草 地碳储量的27%～40%和36%～55%。     

基于景观敏感度的猴石森林公园保护区划

基于GIS技术,选取坡度、相对景点距离、相对游道距离、景点视觉几率和游道视觉几率5个指标分别对猴石森林公园进行敏感度评价,并建立了综合敏感度评价模型,运用层次分析法（AHP）确定各指标权重,进而确定了公园内各区域的综合敏感度等级,将公园相应地划分为4个等级的敏感区.结果表明：研究区Ⅲ级敏感区的面积最大,为495.80 hm²,占公园总面积的38.3%.这一区域在强调保护自然景观的同时,可进行适度开发,提倡利用人文景观美化和衬托自然景观.Ⅳ级敏感区的面积最小,为142.80 hm²,占研究区总面积的11.0%.这一区域的开发潜力最大,可开展大规模的综合性旅游设施和游道布设.Ⅰ、Ⅱ级敏感区的面积依次为297.24和359.72 hm²,分别占研究区总面积的22.9%和27.8%,Ⅰ级敏感区内景观应严格保护,禁止任何人为开发建设,维持自然景观的本色,Ⅱ级敏感区内除简易的林间小道和石阶山道外,严禁开山取石、破坏植被和水体.     

西藏米拉卡黑白仰鼻猴的栖息地变化

黑白仰鼻猴(Rhinopithecus bieti)分布在我国金沙江和澜沧江之间的横断山脉的一个狭小区域内（26°14′N—29°20′N,99°15′E—99°37′E）,海拔分布范围2 600 （南部）—4 200 m（北部）;目前大约有15群,约1 700只。本文所研究的西藏米拉卡猴群分布在我国西藏藏族自治区芒康县的南部,数量约50只。基于野外调查和过去的报道,此地的暗针叶林和针阔叶混交林是猴群的适宜栖息地,而由于人口数量增加所导致的夏季牧场和农田面积不断扩增正在逐渐侵蚀着这里的暗针叶林。为了评估该猴群的栖息地现状、变化趋势和变化原因,我们通过野外调查工作,利用GIS和RS技术,分别解译了当地过去5年(1986—2006年) 冬季的Landsat TM卫星影像,并对解译结果进行了分析和计算,得到了该猴群栖息地的主要结果有：1）2006年暗针叶林面积是13 600 hm²,夏季牧场面积是4 900 hm²,农田面积是3 300 hm²;2）在过去20年（1986—2006年）,暗针叶林面积减少了15.5%（2 500 hm²）,牧场面积增加了58.1%（1 800 hm²）,农田面积增加了17.8%（500 hm²）;3）暗针叶林的斑块数量增加了75.6%,平均斑块面积下降了51.8%（从1986年的15.3 hm²到2006年的7.4 hm²）,最大斑块指数下降了54.7%;景观丰富度并没有变化,但Shannon多样性指数和Shannon均匀度指数分别增加了4.0%;4）暗针叶林面积变化与当地的人口数量呈显著负相关（r＝−1.000）,而夏季牧场和农田面积分别和当地人口呈显著正相关（r＝1.000）。表明黑白仰鼻猴米拉卡猴群栖息地的丧失和破碎化程度较为严重;栖息地丧失和破碎化是当地传统生产方式和人口增长共同作用的结果。     

西双版纳地区土地利用的空间分析

利用西双版纳地区2003年TM数据,对土地利用结构及土地利用与海拔、坡度、水系等自然地理要素相互关系的空间进行分析.结果表明,耕地、林地和草地是该地区土地利用的主体,其中林地面积13 420 km²,占研究区总面积的74%;草地面积3 251 km²,耕地面积2 332 km²,分别占13%和18%.林地、耕地和草地面积随海拔高度具有单峰变化的曲线特征,在海拔1 000～1 200 m处林地分布最多,耕地和草地面积达到峰值时的海拔约为900 m.受人为活动影响强的用地类型坡度指数较低,城乡建筑用地和耕地的坡度指数为5°和14°,人为活动影响较弱的林地草地坡度指数较高,分别为22°和20°.河谷内随缓冲距离增加,土地利用呈现规律性变化,耕地、城镇居民点、未利用地3种土地利用方式主要集中在河谷底部近水域处,远离河谷林地草地组分增加明显.西双版纳地区自然生态系统相对原生,具有林地为基质,河流为廊道,坝区、沟谷农业景观镶嵌分布的特点.     

汶川地震区灾后植被恢复时空过程及特征——以都江堰龙溪河流域为例

定量评估地震区灾后植被恢复,对于灾区生态系统恢复重建及区域社会经济可持续发展规划具有重要科学意义.以都江堰龙溪河流域为案例区,采用MODIS-NDVI的时间序列数据,确定植被恢复评估的Landsat影像时间,并以Landsat影像定量揭示龙溪河流域植被在“5.12”汶川地震前后的动态变化;进而根据区域水系和地形因子,定量解析并揭示植被覆盖度受损恢复率的时空变化特征.结果表明:研究区植被覆盖受损恢复情况整体较好,但植被覆盖度对地震损害的响应存在滞后现象;受损植被恢复率与河流水系距离、海拔、坡度和坡向存在显著的相关性.本研究结果可为地震灾后植被恢复的决策干预提供技术支撑.     

Monitoring vegetation recovery after China’s May 2008 Wenchuan earthquake using Landsat TM time-series data: a case study in Mao County

The Wenchuan earthquake (Richter scale 8) on 12 May 2008 in southwestern China caused widespread ecosystem damage in the Longmenshan area. It is important to evaluate natural vegetation recovery processes and provide basic information on ecological aspects of the recovering environment after the earthquake. To circumvent the weather limits of remote sensing in the Wenchuan earthquake-hit areas, and to meet the need for regional observation analyses, three Landsat TM images pre- and post-earthquake in Mao County were used for analysis. Post-earthquake normalized difference vegetation index (NDVI) values were compared to pre-earthquake values with an NDVI-based index differencing method to determine the extent to which the vegetation was damaged in relation to the pre-earthquake pattern, and the rate of recovery was evaluated. The spatial characteristics of vegetation loss and natural recovery patterns were analyzed in relation to elevation, slope and aspect. The results indicated that severely damaged sites occurred mainly in river valleys, within a range of 1,500?C2,500?m elevation and on slopes of 25?C55°. The distance from rivers, rather than the distance from active faults, controls the damage patterns. After 1?year of natural regeneration, 36?% of the destroyed areas showed a decrease in NDVI value, 28.8?% showed very little change, 19.1?% showed an increase, and 16.1?% also increased with a recovery rate greater than 100?%. Moreover, there is a good correlation between recovery rate and both slope and elevation, but recovery patterns in the damaged area are complicated. Our results indicate that natural recovery in this arid valley is a slow process.     

A study on the relationship between vegetation pattern and environment in the upstream of Minjiang River,China

The vegetation pattern in the upstream of Minjiang River,and its relationship with environment factors,such as landscape position(elevation,slope,aspect),precipitation and temperature and soil are analyzed in this paper.The data used in this Paper were based on the landscape map derived from 1994 TM imagery.The results were as follows:1)dominant landscape types were forest,shrub land and grassland,which were very similar in terms of area ratio(32.87%,31.85% and 28.44%,respectively);2)the patch shape of conifer forest and mixed forest was complicated while that of broad-leaved forest and cultivated land was simple;3)the fragmentation of conifer forest and mixed forest was serious in contrast with low fragmentation of broad-leaved forest and cultivated land;and 4)closed scrub and grassland had a high contagion and good connectivity while mixed forest had a lower contagion and bad connectivity.In addition,the vegetation distribution pattern of upstream of Minjiang River Was closely related with elevation and temperature,but the relationship between vegetation and precipitation was not statistically significant.     

A study on the relationship between vegetation pattern and environment in the upstream of Minjiang River, China

The vegetation pattern in the upstream of Minjiang River, and its relationship with environment factors, such as landscape position (elevation, slope, aspect), precipitation and temperature and soil are analyzed in this paper. The data used in this paper were based on the landscape map derived from 1994 TM imagery. The results were as follows: 1) dominant landscape types were forest, shrub land and grassland, which were very similar in terms of area ratio (32.87%, 31.85% and 28.44%, respectively); 2) the patch shape of conifer forest and mixed forest was complicated while that of broad-leaved forest and cultivated land was simple; 3) the fragmentation of conifer forest and mixed forest was serious in contrast with low fragmentation of broad-leaved forest and cultivated land; and 4) closed scrub and grassland had a high contagion and good connectivity while mixed forest had a lower contagion and bad connectivity. In addition, the vegetation distribution pattern of upstream of Minjiang River was closely related with elevation and temperature, but the relationship between vegetation and precipitation was not statistically significant. __________ Translated from Journal of Beijing Normal University (Natural Science), 2005,41(4) [译自: 北京师范大学学报(自然科学版), 2005,41(4)]     

岷江上游高原植被类型与景观特征对土壤性质的影响

土壤空间异质性是土壤的重要属性之一采用地统计学的理论和方法与传统统计学原理,研究了青藏高原东缘高原面土壤性质的空间异质性及其理化因子和植被类型、景观位置的相关性。变异函数分析结果表明,土壤水分与养分元素具有明显的空间异质性由于植被类型与景观性质的影响,利用传统统计学方法,对研究的样地进行了分类统计,结果表明,植被类型与土壤养分之间的相关性很大,海拔高度也是影响养分与水分分布的一个重要因子,灌丛群落类型土壤质量指数高;不同坡位对养分的影响具有相同的趋势,对于不同海拔的地貌来说,丘陵组下坡位>上坡位>中坡位,而低山组为下坡位>中坡位>上坡位;坡面尺度上土壤养分的空间变异受景观性质与生态系统类型的综合影响。     

岷江干旱河谷植物群落的复杂性

通过对岷江干旱河谷植被及环境因子的系统取样调查,研究了该地区植物群落复杂性及其与环境因子的关系,探讨了群落复杂性与多样性、均匀度、物种丰富度之间的关系.随着海拔的增加,群落总复杂性和结构复杂性均表现为“高-低-高”的变化趋势,表明高海拔和低海拔段有较高的复杂性,中海拔段复杂性较低;位于干旱河谷核心区的样带3、4较北部过渡区样带1、2和南部过渡区样带5、6有着较低的群落总复杂性;不同坡位、坡形及坡向,群落总复杂性和结构复杂性,均表现为上坡位＞下坡位＞中坡位,凹坡＞平破＞凸坡,阴坡＞半阴半阳坡＞阳坡.华帚菊-小黄素馨灌丛的总复杂性最高,西南野丁香灌丛、驼绒藜灌丛的总复杂性最低,橿子栎灌丛和群小花滇紫草灌丛的结构复杂性较高; 群落总复杂性与有机质、全N、土壤含水量、水解N、速效K呈现出显著的二次曲线关系,与全K、全P、速效P、pH值没有明显的相关关系.总复杂性与多样性、均匀度、物种丰富度的关系密切,均呈现显著的线性正相关关系.均匀度和结构复杂性呈现极显著的线性负相关,表明结构复杂性随均匀度的增加而减小.作为群落总复杂性与多样性的区分,结构复杂性对群落内物种数的变化较为敏感,不仅与均匀度有关,还与群落物种数量有关.结构复杂性和多样性作为群落总复杂性的两个组成部分,对总复杂性的影响随着研究区域和群落的不同而不同.     

Spatial relationships between NDVI and topographic factors at multiple scales in a watershed of the Minjiang River,China

Improvement in vegetation cover in the upper reaches of the Minjiang River protects major freshwater sources and constructs ecological barriers in the upstream of Yangtze River located in southwest China. However, the spatially varying relationships between normalized difference vegetation index (NDVI) and topographic factors at multiple scales remain unclear. In this study, the two-dimensional discrete wavelet transform (2D-DWT) and geographically weighted regression (GWR) were combined to build a framework for examining the complex spatial relationships between NDVI and topographic factors at multiple scales. Based on the gridded datasets of NDVI and digital elevation model (DEM) of a small watershed located in the upper reaches of the Minjiang River situated in southwest China, the influence of topographic factors on NDVI variation in each grid and which topographic variables correlated most with the NDVI at each location were analyzed in this study. The grid data were decomposed into smooth and detail components using 2D-DWT. The results revealed that elevation, slope, and aspect exhibited different scale effects on NDVI in different wavelet components. In the smooth components, the spatial correlation of NDVI with elevation, slope, and south-facing index (SFI) of aspect increased with the decomposition scale, whereas topographic factors had different degrees of influence on NDVI. Elevation was found to be the most important topographic factor that determined the spatial distribution of NDVI on both sides of the valley, and SFI exhibited the highest effect on NDVI when elevation was higher than 2500 m. In the detail components, the spatial distribution of the most important topographic factor affecting the NDVI was not evident at a smaller scale, whereas it became obvious at 480 m scale. SFI was found to be more important than elevation and slope at a larger scale. These results will help in understanding the complex relationship between NDVI and topographic factors and determining the appropriate topographic location for ecological restoration.