1990—2010年间我国北方农牧交错带植被覆盖度变化归因

The attribution of variation of the plant coverage degree in the agricultural-animal region of northern China during 1990—2010

以我国北方传统农牧交错带为研究区,以植被归一化指数(NDVI)表征地表植被覆盖度,对土地利用数据和降水量、气温等气象数据两大类影响因子进行相关性分析.研究发现:1990—2010年该地区主要土地利用类型发生了显著的相互转化,但占优势的仍是草地、耕地和林地,土地利用和景观结构未发生重大变化.研究期间,北方农牧交错带耕地、林地和未利用土地植被覆盖度均有所增加,草地植被覆盖度有所减少.植被覆盖度与年均降水量呈极显著相关性,1990—2010年农牧交错带降水呈减少趋势,植被覆盖度上升趋势明显.植被覆盖度与同期年均气温数据也呈现一定的正相关性,1990—2010年农牧交错带气温变化属于升温趋势,植被覆盖度上升趋势明显.研究表明北方农牧交错带植被覆盖度变化是在全球气候变化和人类活动的双重影响下发生的,土地利用变化和降水、气温气象数据两种因素对植被覆盖度的影响具有明显的地域性特征,土地利用变化因子的影响由于受政策和人类活动的参与而正逐渐占据着主导地位,而气候条件中,气温升高对植被覆盖度具有一定的正相关性,降水量因子在径流量充沛地区影响作用较弱,但在水源缺乏,人类活动干预较少农牧交错带西北地区仍然有着重要的影响作用.

Agricultural-animal region of northern China is one of sensitive reaction of the ecological transition zone type ;its change of vegetation coverage is influenced and intervened by many factors . This paper analyzed two group of factors （land use data and meteorological data such as amount of precipitation and temperature ） based on NDVI representing vegetation fraction in agricultural-animal region of northern China . This study found that ：the main type of land use in this area had dramatically transformation in 1990-2010 ,but the dominant was cropland ,grassland and woodland , land use and landscape structure changed very little .During the study ,cropland、woodland and unused land vegetation coverage had a rise ,grassland vegetation coverage decreased less .Vegetation coverage were extremely significant correlation with annual rainfall , precipitation of the agricultural-animal region presented decreasing tread in 1990-2010 ,vegetation coverage raised significantly .Vegetation coverage and over the same period the average annual temperature data over the same period also presented certain positive correlation ,in agricultural-animal region ,temperature change belonged to the warming trend in 1990-2010 , vegetation coverage raised significantly . The research results showed the change of vegetation coverage in northern agricultural-animal region occurred in the dual influence of global climate change and human activities ,the change of land use and meteorological data such as amount of precipitation and temperature had obvious regional characteristics ,the influence of change of land use had the leading role gradually because of the policy and the participation of human activity ,but in climatic conditions ,temperature rise had a certain positive correlation according to vegetation coverage ,precipitation factor effected on the weaker in runoff energy region ,but it also had important effect on water shortage ,less intervention of human activity especially in agricultural-animal region of northwest territories .