黄土高原西部弃耕地植被恢复与土壤水分调控研究

Vegetation Rehabilitation and Soil Moisture Control in Abandoned Plowlands on Western Loess Plateau

选择黄土高原半干旱偏旱区2a、3a、4a、5a、7a、9a、12a、20a的弃耕台地和天然台地，调查各弃耕地和天然台地的植物种类、数量、盖度、频度和地上生物量，定期采样分析各样地0～100cm土层土壤水分。结果表明：农田弃耕后植被沿天然植被方向演替，在演替过程中，植物种类数量逐渐增加，但在弃耕9a后开始减少，20a后接近于天然台地；更耐旱的多年生草本和小灌木种增加；除7～9a波状变化外，植被盖度和地上生物量呈逐渐减少趋势，弃耕初期的植被盖度和地上生物量显著大于弃耕12a后和天然台地；12a和20a弃耕地0～100cm土层含水量高于其他弃耕地和天然台地，弃耕初期表层土壤含水量较高，天然台地含水量居中，但其植被对水分利用的时间延长，范围扩大，表明天然台地植被的水分利用率提高，植被群落更加稳定。

We selected the abandoned plowlands on Loess Plateau which had been abandoned for 2 years, 3 years, 4 years, 5 years, 7 years, 9 years, 12 years and 20 years as sampling sites and natural mesa as the Check; then investigated their plant species, species numbers, coverage, frequency, and aboveground biomass, also measured the soil moisture in the depth of 0～100 cm. The complete investigation in total 54 samples has shown the results as follows： The vegetation succession in abandoned farmland went toward the natural vegetation, in the process, the number of species increased in initial stage of succession but decreased after 9 years, and got close to the species number of natural land after 20 years; more drought-resisting perennial herbs and shrubs increased; the coverage and aboveground biomass tended to decrease except for fluctuation in the duration of 7 ～ 9 years, that in the initial abandoned lands were significantly greater than that of abandoned land after 12 years and that of natural land; the accumulated soil moisture in the 0～100 cm layer of abandoned lands with duration of 12 years and 20 years were more than that of the other abandoned lands and natural tableland, and the soil moisture in the 0～40 cm layer of initially abandoned lands were higher than that of the others. The changes of soil moisture showed that the water utilization ratio of vegetation in natural tableland was higher and vegetation community was more stabilization than that of abandoned lands.