温度与降水变化的小波分析及其环境效应解释——以东北农牧交错区为例

中国东北农牧交错区属于环境变化的过渡区域和敏感区域 ,是最容易感受气候变化的地带之一。该文运用小波分析方法 ,对 5 0年代以来东北农牧交错区典型站点的温度和降水变化情景进行了分析 ,主要分析了其变化的多尺度特征和规律 ;区域和样地分析结果表明 ,降水与温度的时空变化是导致土地退化和环境变化的重要驱动力

Wavelet analysis of temperature and precipitation changes and their environmental effects

The vulnerability of eco-environment and its sensitivity to global environmental change characterize the transitional area of farming and pasturing in Northeast China. The moisture regime is a principal factor, by which the spatial differentiation and variation of the physiographical environment are influenced directly. The temperate and precipitation changes in the last 45 years (1951～1995) were analyzed using wavelet analysis method, mainly on the multi-scale properties and law of the changes. The result of the wavelet analysis indicates that changes of the precipitation at each sampling site were dynamic and the distribution of the relative higher and the lower period was in alternation. During the 45 years, the variation trend of the precipitation was impalpable. The temperature changed periodically but rose gradually in the 45 years. An important reflection to regional environmental change is desertification. The relation between the temporal and spatial distributions of precipitation and the plant growth also was analyzed. The result shows that the fluctuation coefficient of plant output is greater than that of precipitation. This phenomenon has a significant effect on the structure and the function of the regional system and the expansion of desertification. By using the vegetation index (NDVI), the result of comparison of land cover for two periods of time indicates that under the impact of the natural conditions and the human activities, regional change of land cover is obvious. The seasonal change of NDVI values of different vegetations shows that the correlation between monthly average NDVI and precipitation is 0.871～0.953, and the correlation between monthly average NDVI and the temperature is 0.832～0.895. For the study area, the trend of land desertification and salinization did not change at all from the 1950s to the 1990s. The vulnerable soil parent materials, strong wind force as well as concentrated precipitation and its great annual variations have effective impact on the desertification in the area. So the temperature and precipitation change is the major driving force for the land degradationand the environmental change.