渭北残塬沟壑区牧草枯落物对油松和侧柏纯林土壤极化的修复效应

纯林对土壤养分的选择性利用和单一枯落物的特殊影响是导致人工林土壤极化的重要原因，利用牧草枯落物施肥或直接营造林草复合植被是防治和修复纯林土壤极化的最快捷且有效的措施。针对渭北残塬沟壑区的油松（Pinus tabuliformis）和侧柏（Platycladus orientalis）人工纯林，在前期关于土壤极化的研究基础上，通过7种常见豆科牧草枯落物与林地腐殖质层土壤的混合培养试验，研究不同牧草枯落物对针叶纯林土壤极化的修复效应，以此作为选择适宜修复牧草种的依据。结果表明：对油松纯林土壤，苜蓿（Medicago sativa）具有明显的综合修复效应，其次为红豆草（Onobrychis viciaefolia），可作为与油松复合种植的优选牧草，而胡枝子（Leapedeza bicolor）、毛苕子（Vicia villosa）和沙打旺（Astragalus adsurgens）造成土壤性质一定的衰退；对侧柏纯林土壤，红豆草具有明显的综合修复效应，其次为苜蓿和草木樨（Melilotus officinalis），可作为与侧柏复合种植的优选牧草，而毛苕子和小冠花则造成土壤性质一定的衰退。

Restoring Effects of Grass Litter on the Soil Polarization of Pinus tabulaeformis and Platycladus orientalis Pure Forests in the Loess Gullied Area

The selective utilization and special effects of pure forest on soil nutrient and litter are considered as fundamental reasons leading to soil polarization. The most rapid and effective measures to prevent and restore this problem are the fertilizing of forest soil using grass litter and the establishment of tree-grass complex vegetation. In order to select the appropriate grass species for preventing the soil polarization of the pure planted forest in the loess gullied area, the grass litters of seven legume species and the humus soils of Pinus tabulaeformis and Platycladus orientalis pure forests were sampled for mixed incubation experiment in laboratory and the restoring effects of the grass litter on the polarized soil were analyzed. Results showed that Medicago sativa and Onobrychis viciaefolia had better comprehensive remediation effects on the soil properties of Pinus tabulaeformis pure forest and were able to be used as the optimization herbages of compound planting, whereas Leapedeza bicolor, Vicia villosa and Astragalus adsurgens hadcomprehensive deterioration effects. O. viciaefoli, M. sativa and Melilotus officinalis had better comprehensive remediation effects on the soil properties of Platycladus orientalis pure forest and were able to be used as the optimization herbages of compound planting, while V. villosa and Coronilla varia hadcomprehensive deterioration effects.