黄土高原土壤含水量对退耕还林（草）的响应

发布时间：2018-03-14 00:05

本文选题：黄土高原　切入点：土壤水分　出处：《西北农林科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：黄土高原地区水土流失严重,生态环境十分脆弱,为了改善黄土高原地区生态环境状况,我国于1999年实施了退耕还林还草工程。在黄土高原地区土壤水分是制约植被建设的主要因子,同时退耕植被的种植对土壤水分的变化也有很大的影响。多年来已有众多学者分别研究了黄土高原各地区退耕还林工程对土壤水分变化的影响作用,但大多数研究只针对某一地区或某一、两种因素对土壤水分变化的影响。为了更全面的研究分析黄土高原地区退耕还林还草工程对土壤水分变化的影响,本论文采用整合分析的方法,以众多学者的研究数据为基础,把黄土高原地区进行详细分区,整合各分区的退耕植被土壤水分数据,从降雨、植被类型、植被年限和植被密度四个方面全面分析了退耕植被对黄土高原地区土壤水分的影响。本研究的主要结论如下:1.黄土高原多年平均降雨量保持稳定、由南向北减少,降雨不均匀程度表现为干旱区半干旱区半湿润区。空间上,土壤含水量由南向北逐渐减少,与多年平均降雨量空间分布规律一致;时间上,土壤含水量大小关系表现为10月6月9月7月8月。2.在半干旱和半湿润地区不同植被类型土壤含水量关系表现为农地荒地苜蓿草地灌木林和乔木林。因此在退耕还林过程中应根据当地降雨条件选择适宜的退耕植被。3.在黄土高原半干旱和半湿润地区,退耕植被土壤含水量随种植年限的增加逐渐减小。因此在退耕植被过程中应控制好植被种植年限,避免因植被种植年限过高导致土壤水分被严重消耗。4.在半干旱和半湿润地区退耕植被随种植密度的变化表现出相同的规律,即各退耕植被随着种植密度的增加土壤含水量减小。这是由于高密度植被生长需要更多的水分,在土层中的根系比低密度植被要多,吸收的土壤水分多,造成土壤水分的减小。因此在退耕还林过程中应根据当地实际气候条件选择合理的密度,而不是一味追求高密度、高覆盖度。
[Abstract]:In order to improve the ecological environment in the Loess Plateau, the soil and water loss is serious and the ecological environment is very fragile. In 1999, the project of returning farmland to forest and grass was carried out in China. Soil moisture is the main factor restricting the construction of vegetation in the Loess Plateau. At the same time, the planting of returning farmland vegetation also has a great influence on the change of soil moisture. Over the years, many scholars have studied the effects of conversion of farmland to forest on soil moisture change in various areas of the Loess Plateau. However, most of the studies only focus on the effect of two factors on soil moisture change in a certain area or a certain area. In order to study the effect of conversion of farmland to forest and grass on soil moisture change in Loess Plateau, most of the studies only focus on the effect of two factors on soil moisture change. This paper adopts the method of integration analysis, based on the research data of many scholars, divides the Loess Plateau area in detail, integrates the soil moisture data of returning farmland vegetation from the rainfall, the vegetation type, The effects of returning cultivated vegetation on soil moisture in Loess Plateau were analyzed in four aspects: vegetation age and vegetation density. The main conclusions of this study are as follows: 1. The annual average rainfall of Loess Plateau remains stable, and decreases from south to north. In space, soil moisture content decreases gradually from south to north, which is consistent with the spatial distribution of annual average rainfall. The relationship between soil moisture content and soil water content is as follows: on October, September September September .2.The relationship between soil moisture content of different vegetation types in semi-arid and sub-humid areas is shown as shrubbery and Arbor forest of alfalfa grassland on farmland wasteland, so the soil water content is returning to cultivated land. In the process of forest restoration, suitable vegetation should be selected according to the local rainfall conditions. 3. In the semi-arid and sub-humid areas of the Loess Plateau, The soil moisture content of returning cultivated vegetation gradually decreases with the increase of planting years. Therefore, it is necessary to control the planting years of vegetation in the process of returning cultivated vegetation. Avoid serious consumption of soil moisture due to excessive planting years. The change of returning vegetation with planting density shows the same regularity in semi-arid and sub-humid areas. That is, with the increase of planting density, the soil water content of each returning vegetation decreases. This is because the high density vegetation needs more water, the root system in the soil layer is more than the low density vegetation, and the soil moisture is absorbed more. Therefore, the reasonable density should be chosen according to the local climatic conditions, rather than pursuing high density and high coverage in the process of returning cropland to forest.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S152.7

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