晋西黄土残塬沟壑区刺槐人工林土壤水分植被承载力研究

为明确在干旱缺水地区,植被对深层土壤水分的过度消耗以及水资源的承载能力,在晋西黄土残塬沟壑区选取林分密度1 300株/hm~2的刺槐人工林为研究对象,以裸地为对照,利用Enviro-SMART土壤水分监测系统(FDR)和热扩散探针(TDP)技术对当地刺槐人工林地0—150 cm范围内各土层体积含水量与树干液流量进行长期连续定位观测,采用土壤有效水与单株刺槐耗水量的比值来衡量研究区刺槐人工林土壤水分植被承载力。结果表明:(1)月降水量和月土壤储水量是决定刺槐人工林土壤水分植被承载力的主要环境因子,且二者与土壤水分植被承载力之间均呈现显著的正比例关系(P0.05)。(2)根据构建的刺槐人工林土壤水分植被承载力模型,计算出当地林龄为19年的刺槐人工林0—150 cm土层深度的土壤水分植被承载力为1 224株/hm~2,稍小于研究区实际林分密度(1 300株/hm~2),为保证当地刺槐人工林分耗水深度控制在0—150 cm土层范围内,同时也为促进当地林分生产力处于最优水平,建议在今后的营林造林过程中将刺槐人工林密度控制在当地土壤水分植被承载力范围之内,在减少林地深层水分消耗、调整林地土壤水资源平衡的同时,促进当地林业产业的合理发展。

Study on Soil Water Vegetation Carrying Capacity of Robinia pseudoacacia Plantation in the Loess Gully Area of Western Shanxi Province

In order to clarify the excessive consumption of deep soil moisture by vegetation and the carrying capacity of water resources in arid and water-deficient areas, the Robinia pseudoacacia plantation with a stand density of 1 300 trees/hm² was selected as the research object in the gully area of the Loess Plateau in Western Shanxi Province, and the bare land was taken as the control. The volumetric water content of soil layers in the 0-150 cm range and trunk sap flow of the local R. pseudoacacia plantation were continuously observed by using Enviro-SMART soil moisture location monitoring system and thermal diffusion probe (TDP). Using the ratio of available soil water to water consumption per plant of R. pseudoacacia to measure the carrying capacity of soil water and vegetation of R. pseudoacacia plantation in the study area. The results showed that:(1) Monthly precipitation and monthly soil water storage were the main environmental factors determining soil water and vegetation carrying capacity of R. pseudoacacia plantation, and there was a significant positive relationship between them and soil water and vegetation carrying capacity (P<0.05). (2) According to the soil water and vegetation carrying capacity model of R. pseudoacacia plantation, the soil water and vegetation carrying capacity of 0-150 cm soil layer depth of R. pseudoacacia plantation with 19 years of local age was calculated to be 1 224 plants/hm², slightly less than the actual stand density of the study area (1 300 plants/hm²). In order to ensure that the water consumption depth of the local R. pseudoacacia plantation is controlled within the 0-150 cm soil layer, and to promote the productivity of the local stand at the optimal level, it is suggested that the density of the plantation should be controlled within the carrying capacity of the local soil moisture and vegetation in the future afforestation process, so as to reduce the deep water consumption of the forest land and adjust the balance of soil water resources in the forest land, and promote the rational development of local forestry industry.