近百年中国华北农牧交错带与非洲Sahel地区环境变化的比较分析

Comparison Analysis of Environmental Changes Between Sahel and Agro-pastoral Zone in Northern China

非洲Sahel地区与中国华北农牧交错带在环境特征及演变过程中体现出许多相似之处,存在明显内在联系。对两个地带近百年降水变化、植被覆盖、干旱事件和沙尘事件对比分析,可以对我国干旱/半干旱地区环境变化的相关科学问题有更好认识。两个地区年降水量序列的年代际变化趋势有很大相似性。非洲Sahel地区年降水量在1950s以前存在明显的年际变化特征,从1960s中期起主要以年代际变化为主;其大部分地区植被覆盖表现为增长趋势;降水量年代际变化可能是影响该地区干旱的重要因素,温度变化也可能存在作用;该区沙尘暴频次年际、年代际变化与降水量相应尺度变化有显著关系,年均温变化和天气变率可能具有一定影响。华北农牧交错带年降水量以年际变化为主要特征,有明显低频波动;该带偏北和偏东地区植被覆盖增长比较显著,南部部分地区植被覆盖呈下降趋势;降水量年代际变化是影响该地区干旱的重要因素,但相同降水量可能引发不同程度的干旱;该带春季沙尘暴频次与前冬温度变化及天气变率有密切联系,与春季降水量也有一定关系。

Sahel is similar to agro-pastoral zone in Northern China in some aspects concerning environmental characteristics and environmental change, and there are some obvious linkages between them. The comparison analysis between them in precipitation, vegetation, drought events and dust storms can help better understand the variability of environment and climate in semiarid/arid regions in China and Sahel. Their interdecadal changes of precipitation have the similar trends. For Sahel, the interannual variability in precipitation is dominant before 1950s, while the interdecadal changes are outstanding from the mid of 1960s. A large portion of Sahel shows an increasing trend in NDVI. The interdecadal change of precipitation may be an important factor for the occurrence of drought, and temperature may also play roles in the formation of drought. The dust storm frequency has some evident relationship with precipitation on the interannual and interdecadal timescales, and the annual mean temperature and synoptic variability also have some influence on it. In agro-pastoral zone in Northern China, the interannual change is an outstanding characteristic in annual precipitation. In the north and east part of the zone vegetation experiences the increasing trend, and the south part Shows a decreasing trend. The interdacadal change of precipitation played a role in the forming of drought events, but the same amount precipitation reduction may cause different drought in intensity. The spring dust storm frequency has tight relationship with previous winter temperature and synoptic variability, and also has some link with spring precipitation.