半干旱黄土区地上生物量对立地因子的响应

Response of aboveground biomass to the standing condition factors in semi-arid region of Loess Plateau

半干旱黄土区地形破碎、沟壑纵横、生态环境脆弱,其生态恢复过程受到全世界生态学者的普遍关注。生物量是生态系统获取能量的表现形式。以位于黄土丘陵沟壑区的植被自然恢复10 a的合沟流域地上生物量为研究对象,分析不同立地因子对地上生物量的影响规律。结果表明:1)不同立地类型地上生物量从大到小依次为沟底、阴向沟坡、阴向梁坡、阳向沟坡、梁顶、阳向梁坡;2)梁坡和沟坡的地上生物量随坡度升高均呈现反S形态,梁坡的地上生物量最大值出现在20°～25°处,最小值出现在35°～40°处,沟坡的地上生物量的最小值出现在30°～35°处,最大值出现在40°～45°处;3)坡向对地上生物量的影响是显著的(P=0.049),其余因素的影响不显著。可知,该区地上生物量的分布规律是植被对不同立地类型水分、光照等自然条件综合利用的结果。

Environmental problems of Loess Plateau in western China,due to its broken terrain,complex hilly-gully system and fragile environment,have been noticed by almost all of ecologists around the world.The biomass is the reaction of energy for the ecosystem,so the aboveground biomass of after 10 years restoration was measured,and its distribution rule under different standing conditions were analyzed.The results showed that the aboveground biomass under different standing conditions decreased with the order of floor of trench,ditch in shady slope,ridge in shady slope,ditch in sunny slope,ridge top and ridge in sunny slope.The aboveground biomass at ditch and ridge slopes presented converse S type along with the elevating of slopes.At ridge slope,the maximum value of aboveground biomass appeared at 20°-25°,and the minimum value at 35°-40°,while at ditch slope,the maximum value appeared at 40°-45°,and the minimum value at 30°-35°.The effects of slope aspect on the aboveground biomass was remarkable（P=0.049）,and the effects of other factors were not remarkable.Therefore,it is proposed that the distribution of the aboveground biomass is affected synthetically by soil moisture,light and other factors.