黄土丘陵林地土壤侵蚀与土壤性质变化

以黄土丘陵子午岭土壤侵蚀和生态环境观测站1989~1998年的观测资料为基础,研究分析了林地开垦10年内土壤侵蚀与生态环境变化的相互效应关系。分析指出:林地开垦人为改变侵蚀环境,引起的人为加速侵蚀速率为自然侵蚀速率的1000倍以上;以单位降雨侵蚀力引起的侵蚀量作为衡量指标,指出林地开垦地土壤侵蚀强度随侵蚀年限增长呈递增加剧趋势;通过分析土壤物理力学性质表明,林地开垦侵蚀10年土壤粘粒和物理性粘粒比林地分别减少2.74%和3.01%,土壤向粗骨化趋势发展,>0.25 mm水稳性团粒含量减少58.7%,土壤容重增大,抗剪强度下降,抵抗径流冲刷能力减弱,造成土壤侵蚀更易发生;应用相关分析表明,>0.25 mm水稳性团粒含量的改变对土壤侵蚀强度影响最大,其偏相关系数为0.9728,其次是土壤的粗粉粒和抗剪强度,偏相关系数分别为0.8879和0.6020;分析>0.25 mm水稳性团粒含量和抗剪强度与土壤侵蚀强度关系表明,林地开垦后侵蚀1年和侵蚀7年为土壤侵蚀加剧的转折年限,说明退化的侵蚀土壤和退化的生态环境加剧了土壤侵蚀的发生和发展。

Soil erosion and soil properties in reclaimed forestland of loess hilly region

Based on the data observed from 1989 to 1998 in Ziwuling, the change of soil erosion and soil physico-mechanical properties was studied after forestland reclamation. When the man-induced factors changed the eco-environment by reclaiming forestlands, the intensity of man-made soil erosion in reclaimed lands was 1000 times more than that of the natural erosion to forestlands. From the analysis of soil physical mechanics properties, the clay content and physical clay content decreased 2.74% and 3.01% respectively, and the > 0.25 mm water stable aggregate content also decreased 58.7%, the soil unit weight increased and the soil shear strength decreased, all of which were easier to cause soil erosion. The results of the correlation analysis showed that > the 0.25 mm water stable aggregate content was the maximum affecting factor to soil erosion, the partial correlated coefficient was 0.9728, and then were soil coarse grain and soil shear strength, the partial correlated coefficients were 0.8879 and 0.6020 respectively. The relation between the >0.25 mm water stable aggregate content, the soil sheer strength and the soil erosion intensity were analyzed.