区域尺度上气候—NDVI—植被—土地利用的关系研究

The vegetation-climate relationship, a main topic in vegetation ecology, is becoming a vital issue under the global change sped up by human activities.The terrestrial transect firstly proposed by IGBP is a valuable tool to study the response of vegetation dynamics of terrestrial ecosystems to global change in climate, land use and atmospheric composition. It facilitates interdisciplinary, integrative global change research, and has already been adopted in many other international programs now. Northeast China Transect (NECT), one of the four initial IGBP transects, was taken as an example to study the relationship between vegetation and environments. Basic eco-geological database containing basic information of NECT such as soil type and characteristics, vegetation composition, climatic data, field investigated data and collective materials from each county or banner were set up by the use of 3S technologies (GPS, GIS and RS). According to these data sets, the quantitative correlation of climate, NDVI and vegetation, and their variations under future different global change scenarios were studied at two levels, community and regional scale. The main results are shown as below: Fluctuations and trends in temperature and precipitation for the eleven meteorological stations in NECT for the period 1951-1997 were calculated to analyze climate variation in the short-term scale.The annual average temperature all has a significant ascend about 1.35°C, from 0.95~1.82°C, whereas, no significant trends were found from precipitation data. Under double CO2 concentration, mean annual temperature of whole transect might increase 0.76~0.87°C, total annual precipitation increase 20mm~30mm, whereas, NDVI might show a descend trend. Moreover, two method of simple climate departure index and variation coefficient (CV%) were used to analyse inter-annual variation of precipitation from different vegetation types. CV% of precipitation of different vegetation types show a rising trend from east to west, the lowest value located in eastern mixed needle-broadleaf forest, then the meadow steppe, typical steppe and desert steppe, which probably indicate a feedback of vegetation to climate variable. Inter-annual variation of precipitation has no increasing trend along with global warming, it is a fluctuated event in small time scale. Fifty-two sites located at relatively undisturbed areas were selected to analyze the variability of two traits derived from the annual NDVI curve, the annual integral of NDVI (NDVI-I), the difference between maximum and minimum NDVI (NDVI-MM). NDVI-I declined from east to west and had a significant variation among different zonal vegetation types. The precipitation of previous year in summer and of current year in winter have a significant correlation with NDVI-I, and the climatic variables having significant correlation with NDVI-MM are the same two, precipitation of current year in autumn and of previous year in summer. According to Ecological Information System (EIS) satellite data, the 8′8 km Normalized Difference Vegetation Index (NDVI) was applied to the 1:1 000 000 digital vegetation map of NECT, which includes 119 vegetation types. Out of totally 119 vegetation types in NECT, there were 91 types including 6 types of cultivated vegetation, which could reflect the changes of NDVI. A trend of NDVI of 10 combined vegetation types is: Swamp vegetation > Mixed needle leaf and broadleaf forest > Needle leaf forest > Broadleaf forest > Cultivated vegetation > Scrub > Meadow > Scrub and grass-forb community > Steppe > Desert. Two types have higher NDVI value, one locates in eastern forest area, another in swamp. Additionally, two issues raising our attention while studying the synergy of the fragile natural environment and the intensive human activities, ecotourism in forest area and grassland degradation. This project could provide policy-maker or further researches in arid and semiarid northern China with some basic principles and data.

在3S技术的支持下研究区域尺度上气候、归一化植被指数、植被和土地利用之间的关系。用高分辨率NDVI动态变化数据数量化1：100万植被图上各类型图斑，建立植被和逐月气候变量与NDVI之间的对应关系，并构建反映土地利用变化的量化指标，分析其对植被的作用。从而揭示区域尺度上的气候变差和土地利用变化对植被的影响及植被的反馈作用。.