2000-2009年青海省植被覆盖时空变化特征

基于2000-2009年MODIS-NDVI植被覆盖指数,采用线性趋势分析、标准差等数理分析方法,对青海省"退耕还林还草"实施10 a来植被覆盖时空变化特征进行分析。结果表明:(1) 2000-2009年青海省植被覆盖呈明显增加趋势为0.018/10 a,远快于三北防护林工程区1982-2006年植被覆盖平均增速0.007/10 a; (2) 2000-2009年青海省植被恢复具有阶段性,"退耕还林还草"实施前6 a,植被覆盖呈现快速上升,2005年后呈波动下降趋势; (3)青海省植被恢复以轻微改善为主(32.66%),中度改善次之(13.32%),明显改善区主要分布在柴达木盆地东南边缘、青海湖盆地、茶卡-共和盆地、河湟谷地及黄南低地; (4)青海省植被呈退化趋势区域比重为18.40%,主要分布于青南高原三江源地区和祁连山中东段;(5)青海省2000-2009年植被稳定性存在明显地域差异。空间格局主要表现为"东南波动,西北稳定,高原温带波动,高原寒带、亚寒带稳定"。青海东部中低山地、丘陵、盆地地区变化幅度最为明显。

Spatial-temporal Characteristics of Vegetation Restoration in Qinghai Province from 2000 to 2009

In order to monitor the dynamic variation of vegetation in Qinghai Province, based on the MODIS-NDVI data from 2000 to 2009, characteristics of spatial and temporal variation were analyzed using statistical methods such as linear trend analysis and standard deviation. Results show that:(1) From 2000 to 2009, vegetation of the study area was improved progressively, with a linear tendency of 0.018/10 a which was faster than the growth rate of the Three North Shelter Forest Program(0.007/10 a) from 1982 to 2006. (2) Vegetation restoration experienced several stages, a rapid increase in vegetation coverage during the first five years of "Grain-for-Green" project and a significantly fluctuated decline after 2005. (3) Slight improvement(32.66%) accounted for the largest proportion of vegetation restoration, followed by moderate improvement(13.32%), and the significant improvement area was mainly distributed in the southeast edge of the Qaidam Basin, Qinghai Lake basin, Chaka-Gonghe basin, Hehuang Valley and the south Yellow River lowland. (4) The proportion of degradation tendency was 18.40%, which was distributed in the three rivers headwater and the eastern section of the Qilian Mountain. (5) Vegetation stability manifested significant regional difference, which was low in southeast and temperate zones, but high in northwest, frigid and sub-frigid zones. The changing magnitude was most obvious in the low mountains, hills and basins in eastern Qinghai Province.