宁南山区人工林草植被与土壤干层互馈机制研究

Soil desiccation and dried soil layer in artificial vegetation had become a serious hidden trouble, which seriously affected the effectiveness of regional vegetation construction and ecological stability. The object of the study was soil and vegetation system under artificial vegetation in the Mountain Area of Southern Ningxia. The breakthrough point was the interaction between vegetation growth and dried soil layer. The data of soil moisture and hydraulic characteristics were measured to calculate soil desiccation index, thickness and original depth of dry soil layer, which were used to analysis temporal and spatial dynamic characteristics of dry soil layer under different types and growth years of vegetation. The vegetation functional traits under dry soil layer stress were monitored included net primary productivity, root characteristics, photosynthetic and transpiration characteristics, and so on. The coupling coordination degree model of vegetation and dry soil layer was used to illustrate the interaction between artificial vegetation and dried soil layer, with the help of topographic and meteorological factors. Soil moisture changes and deep soil desiccation effects of different artificial vegetation and growth years were simulated and calculated with EPIC model (Environmental Policy Integrated Climate). The research could help to prevent and moderate soil desiccations and deterioration of ecological environment, which caused by excessive soil moisture consumption. The results could provide scientific reference for moisture circulation, vegetation restoration and ecological environment construction in the mountain area of Southern Ningxia.

人工林草植被条件下土壤干层的形成，会严重影响区域植被建设成效和生态稳定。本项目以宁夏南部山区典型人工林草植被条件下土壤-植被系统为研究对象，以植被生长与土壤干层的相互作用为切入点，通过土壤水分及水力学特性等多要素观测，计算土壤干燥化指数、干层厚度和起始深度等量化指标，分析不同植被类型和年限下土壤干层时空动态变化特征；同时对净初级生产力、根系特征和光合蒸腾特征等植物生长指标进行监测，分析土壤干层胁迫条件下植被功能性状的变化特征；结合地形和气象要素，利用植被-土壤干层系统耦合协调度模型揭示研究区人工林草植被与土壤干层的互馈关系；利用环境政策综合气候模型（WinEPIC模型）模拟和预测人工林草植被条件下土壤水分和干层量化指标动态过程。研究成果有助于预防与减缓由于土壤水分过量消耗导致的土壤干燥化与区域水分生态环境恶化趋势，为宁南山区水循环、植被恢复和生态环境建设提供科学参考。

人工林草植被条件下土壤干层的形成，已严重影响区域植被建设成效和生态稳定。项目以宁夏南部山区典型人工林草植被条件下土壤-植被系统为研究对象，通过土壤水分、土壤理化特征及水力学特性等多要素观测，分析不同植被类型和林龄下土壤干燥化程度、土壤干层分布深度、广度及影响因素，构建植被和土壤干层的耦合度、耦合协调度模型。结果表明：（1）土壤、植被属性受自然和人为因素的影响，在空间分布上呈现不一致性，空间变异程度和最优半方差拟合函数均呈现出明显的不同。（2）杏树、杨树、榆树、沙棘、柠条、猪毛蒿、野枯草、鼠尾粟和玉米0~600 cm平均SDI分别为63.48%、91.88%、95.17%、87.67%、75.72%、157.81%、186.57%、139.06%和156.02%，即乔木和灌木出现了中度、轻度土壤干燥化现象；3、17、23、35 a的杏树地的土壤平均SDI分别为184.36%、99.87%、74.60%、59.15%，干燥化强度随杏树年限增加而增强。（3）研究区具有禾本科植物12种10属，菊科9种6属，豆科植物7种7属，分别占研究区植物种数23.53%、17.65%、13.73%。丰富度指数和多样性指数呈现草本>灌木>乔木，优势度指数和生物量则呈现相反趋势。（4）杏树、杨树、榆树、沙棘、柠条、猪毛蒿、野枯草、鼠尾粟和玉米S（x）/P（y）值分别为0.4771、0.5173、0.4760、0.6369、0.5400、0.8213、0.8622、0.8865、1.1874。乔木地和灌木地均属濒临失调发展类模式土壤干层滞后发展，弃耕地和草地均属勉强协调发展模式植被与土壤干层同步发展，农地属于初级协调发展模式植被与土壤干层同步发展。研究成果有助于预防与减缓由于土壤水分过量消耗导致的土壤干燥化与区域水分生态环境恶化趋势，为宁南山区水循环、植被恢复和生态环境建设提供科学参考。