黄土高原不同生态系统水土保持服务功能评价

Assessment of Soil Conservation Function of the Ecosystem Services on the Loess Plateau

以土壤保持量为评估指标，应用修正通用土壤流失方程，评估了黄土高原水土保持生态系统服务功能，分析了近20a来的黄土高原土壤保持量的空间分布及其动态变化，对于揭示全球气候变化背景下黄土高原林草植被建设的生态成效具有重要的科学价值和现实意义。结果表明：1990--2010年黄土高原平均单位面积土壤保持量为305t·hm-2·a-1，年均土壤保持总量为190×10^8t。1990--2000年农田、草地和林地生态系统平均单位面积土壤保持量分别为249、285和640t．hm-2．a-1，2000-2010年平均单位面积土壤保持量分别增加了14．6％、2．9％和7．4％。黄土高原草地和林地的土壤保持率分别为83％～88％和94％-97％。农田生态系统土壤保持量的空间分布特征表现为黄土丘陵沟壑区和黄土高塬沟壑区较大，农灌区和河谷平原区偏低；草地和林地生态系统土壤保持量的空间分布特征表现为沿东南向西北减少的变化趋势。与1990-2000年不同，2000-2010年农田、草地和林地生态系统土壤保持量的空间变化特征表现为较为明显的增长趋势，尤其是黄土丘陵沟壑区陕西榆林、延安地区和山西吕梁山区一带。

Taking the amount of soil conservation as the assessment indicator, with the application of the Revised Universal Soil Loss Equation, the soil conservation function of the ecosystem services on the Loess Plateau in China was assessed. The spatial distribution of the amount of soil conservation and its dynamic changes on the Loess Plateau in nearly 20 years was analyzed, which has significantly scientific and practical values in ecological benefits for vegetation reconstruction under the warming and drying climate. The results showed as follows. The per unit area soil conserved on the Loess Plateau was 305 t-hm-2. a-1 between 1990 and 2010, and the total amount of annual soil conserved was 190 × 108 t. The per unit area soil conserved amounts of farmland, grassland and forest ecosystems in 1990- 2000 were 249, 285 and 640 t. hm-2. a-1, respectively, increased by 14.6%, 2.9% and 7.4% in 2000-2010. The percentage of soil retention rate of grassland ranged from 83% to 88%, for forest from 94% to 97% in 1990-2010 on the Loess Plateau. The characteristics of spatial distribution of soil conservation for farmland ecosystem showed that it was the highest in hilly and gully region of the Loess Plateau, and the lowest in agricultural irrigation region and the plain area. The spatial distribution characteristics of soil conservation for grassland and forest ecosystems showed a reduced trend along the southeast to northwest. Compared in 1990-2000, the amount of soil conservation for farmland, grassland and forest ecosystems showed an obvious increment in 2000-2010, especially in the hilly region in Yulin and Yan＇an in Shaanxi Province and Ltiliang Mountain areas in Shanxi Province.