1982～2003年东北地区植被覆盖变化特征分析

利用1982~2003年GIMMS-NDVI数据集和GIS技术,结合多种统计分析方法,定量分析了东北地区植被覆盖时空变化规律。结果显示:(1)1982~2003年东北地区森林、草地和农田植被年内变化曲线均为单峰型,峰值都出现在夏季,森林植被年内NDVI变化曲线峰值最高,农田次之,草地最低。(2)22年期间,森林植被覆盖呈下降趋势;草地和农田植被覆盖总体亦呈下降趋势,但西辽河平原草地和松嫩平原农田植被覆盖呈上升趋势;相同植被类型比较,长白山东北部林地、西辽河平原草地、松嫩平原农田植被覆盖均比较稳定。(3)1982~2003年,东北地区植被覆盖总体呈缓慢下降趋势,其中1982~1992年,东北地区植被覆盖呈增加趋势,植被覆盖增加的面积为545 435 km2,占东北地区总面积的43.91%;植被覆盖减少面积为96 491 km2,占总面积的7.77%;1993~2003年,东北地区植被覆盖呈减少趋势,植被覆盖减少的面积为626 839 km2,占东北地区总面积的50.45%,植被覆盖增加的面积较少,仅为27 025 km2,占总面积的2.18%,且呈零星分布。研究表明,人类活动和自然因素的变化是东北地区植被覆盖下降的主要原因。

Changes of Vegetation Coverage in Northeast China from 1982 to 2003

Based on the remote sensing data,GIMMS-NDVI,technology of GIS and statistical processing,the paper conducted quantitative analyses of spatial-temporal changes of vegetation coverage from January 1982 to December 2003 in the Northeast China.The results showed that:(1) the average annual NDVI curves of vegetation had a single peak in those regions such as forest,grassland and cropland.The NDVI peaks of different vegetation occured in summer.The NDVI peak of forest was highest,cropland took second place and grassland was the lowest.(2) The NDVI variation trends of forest were decreased,the trends of grassland and cropland were decreased,but trends of grassland of Xi Liao River Plain and cropland of Song Nen Plain were increased.For the same type vegetation,the vegetation coverage change of forest in the northeast part of Changbai Mountain,grassland in Xi Liao River Plain and cropland in Song Nen Plain were stable.(3) The changes of vegetation coverage were slowly decreased during the past 22 years in whole area.From 1982 to 1992,the vegetation coverage increased in the Northeast China.The coverage increased areas were(545 435) km2,accounted for 43.91% of Northeast China.The coverage decreased areas were 96 491 km2,accounted for 7.77% of Northeast China.From 1993 to 2003,the vegetation coverage of Northeast China decreased.The coverage decreased areas were 626 839 km2,accounted for 50.45% of Northeast China.The coverage increased areas were 27 025 km2,accounted for 2.18% of Northeast China.The main reasons of decrease of vegetation coverage were the effect of human activities and natural factors in Northeast China.