水保所知识产出(1956---)知识库

黄土高原地区是我国重要的生态屏障和畜牧业生产基地。但不合理的人类活动
导致草地退化严重，水土流失剧烈，生态系统可持续性受到威胁。施行植被恢复措
施，利用植物—土壤系统间的互馈效应，恢复和重建“土壤水库”巨大调节功能，
是解决该区域生态环境问题的根本举措。本研究选取位于黄土高原典型草原区的云
雾山草地自然保护区不同退耕年限的样地为研究对象，采用人工模拟降雨、显微
CT 扫描和室内分析相结合的方法，研究退耕草地植被恢复过程中土壤物理化学和
水力性质的变化规律，分析土壤结构的演变特征，阐明土壤结构演变对降雨入渗过
程的作用机制，以期为黄土高原地区植被恢复重建提供一定的科学依据。取得以下
主要结论：
1、退耕还草过程改善土壤理化性质。表现为降低土壤容重、增加土壤孔隙度，
植被恢复过程中砂粒含量有所降低，粉粒含量有所增加，主要体现在退耕初期（<3
年）和0-10 cm土层，但没有引起土壤质地的改变。退耕3-8年是土壤有机碳、全氮
含量恢复的阶段，从退耕8年开始积累，退耕22-24年是土壤有机碳、全氮含量迅速
积累的阶段。0-10 cm土层土壤有机碳、全氮含量分别从退耕8年、退耕22年开始显
著高于10-40 cm土层。土壤有机碳的积累速度大于全氮的积累速度。
2、退耕还草过程促进大团聚体形成，提高团聚体稳定性。表现为退耕8-24年水
稳性大团聚体含量显著增加了21.34%-52.78%，退耕22-24年团聚体稳定性最强。0-10
cm土层团聚体稳定性高于10-40 cm土层。水稳性大团聚体含量直接提高团聚体稳定
性，与稳定性呈显著正效应，主要体现在>1 mm水稳性大团聚体。有机碳含量间接
提高团聚体稳定性。
3、退耕 3 年后退耕地植被恢复有利于提高孔隙结构稳定性。表现为有利于土
壤 0-10 cm 土层中 1-5 mm 团聚体总孔隙度的提高、孔隙总数的减少。其中，毛管
孔隙度（3.25 μm-20 μm）随退耕年限的延长逐渐降低，退耕 8-22 年降低显著。20
μm-100 μm 通气孔隙的孔隙度随退耕年限的延长逐渐降低，而>100 μm 通气孔隙的孔隙度逐渐提高。>100 μm 通气孔隙的孔隙度最高，占总孔隙的 99%以上。植被恢
复有利于增加狭长孔隙（形状因子≤0.2）的孔隙度，降低不规则孔隙（0.2＜形状因
子＜0.5）和规则孔隙（形状因子≥0.5）的孔隙度。狭长孔隙的孔隙度最高，占总孔
隙度的 99%以上。土壤粉粒含量是影响团聚体孔隙结构特征的最主要因素，与 1-5
mm 团聚体中不规则孔隙度、规则孔隙度、毛管孔隙度呈极显著负相关（Sig.<0.001）。
4、退耕还草过程显著提高了土壤导水和持水性能。随着植被恢复的进行，土
壤饱和导水率从退耕 3 年的 4.16 mm·min -1 提高到退耕 22 年的 6.74 mm·min -1 ，显著
增加了 61.9%。与坡耕地相比，当有机碳含量和水稳性大团聚体含量分别增加 1
g·kg -1 和 1%时，饱和导水率分别提高 1.2%和 2.4%。植被恢复有利于提高土壤持水
能力，主要体现在 0-10 cm 土层，退耕 22-24 年持水性能显著提高。土壤水稳性大
团聚体含量和有机碳含量是影响饱和导水率的主要因素，而有机碳含量是影响土壤
持水能力的最主要因素。有机碳含量增加可通过增加水稳性大团聚体含量来改善土
壤结构，从而提高饱和导水率和持水能力。
5、退耕还草提高了土壤降雨入渗能力。表现为随植被恢复的进行，初始入渗
率增加，达到稳定入渗率的时间延长。植被恢复过程中入渗率随雨强增大而增加。
1-5 mm 团聚体不规则孔隙度和毛管孔隙度是影响初始入渗率的主要因素，与初始
入渗率呈负相关。降雨强度为 60 mm·h -1 时，稳定入渗率与 2-1 mm 团聚体不规则孔
隙度呈负相关。降雨强度为 90 mm·h -1 时，稳定入渗率与 5-2 mm 团聚体狭长孔隙度
呈正相关。
关键词：退耕还草；土壤结构；微型 CT；土壤水力性质；降雨入渗

The Loess Plateau region is an important ecological barrier and the production base
of animal husbandry in China. However, unreasonable human activities lead to serious
degradation of grassland, severe soil erosion, and the sustainable development of threaten
ecosystem. The vegetation restoration measure which takes advantage of the mutual
feedback effect between plants - soil system, recover and rebuild huge adjustment
function of soil reservoir, which is the fundamental measure to solve the problem of the
regional ecological environment. This study selected different years grassland as the
research object, which is in the Yunwu Mountains grassland nature reserve in the loess
plateau. In this paper, we use the methods of artificial rainfall simulation, microscopic
CT scans and indoor analysis. In this paper, In this paper, we study the change rule of soil
physical, chemical and hydraulic properties in the process of vegetation restoration. This
paper analyzes the evolution of soil structure characteristics to clarify the mechanism of
action of soil structure evolution to rainfall infiltration process. We purpose to provide
certain scientific basis of vegetation restoration and reconstruction in loess plateau areas.
The main results obtained are summarized as follows:
1. The process of returning farmland to grassland is conducive to improving soil
physical and chemical properties. Performance to reduce soil bulk density, increase soil
porosity, reduce soil sand content, increase the silt and clay content, mainly reflected in
the early farmland (< 3 years) and 0 to 10 cm soil layer, but did not cause the change of
soil texture. Grain for 3 to 8 years is soil organic carbon, total nitrogen content in
recovery stage, from grain for 8 years began to accumulate, conversion of 22-24 years is  a rapid accumulation of soil organic carbon, total nitrogen content.0 to 10 cm soil layer
soil organic carbon, total nitrogen content, respectively from the field for eight years 22
years is significantly higher than 10 to 40 cm soil layer. Soil organic carbon
accumulation speed is bigger than the accumulation of nitrogen.
2. The process of returning farmland to grass promotes large aggregate formation,
improve the aggregate stability. Performance for the conversion of 8-24 years large
aggregate content of water stability significantly increased by 21.34% - 21.34%,
conversion of 22-24 years most aggregate stability.0 to 10 cm soil aggregate stability
above 10 to 40 cm soil layer. Large aggregate content of water stability directly increase
aggregate stability, and stability was significantly positively effect, mainly reflected in
the > 1 mm large aggregate water stability. Organic carbon content indirectly boost
aggregate stability.
3. Three years after returning farmland grassland vegetation restoration is helpful to
improve the pore structure stability. Performance is beneficial to the soil in the 0 to 10
cm soil layer 1-5 mm together the increase of the total porosity and the pore of the total
reduction. Among them, the capillary porosity (3.25 microns - 20 microns) with
gradually reduce, increase of fixed number of year of the farmland conversion of 8-22
years reduced significantly.20 microns - 100 microns ventilation pore porosity with the
extension of cultivated fixed number of year of reduced gradually, and > 100 microns
ventilation pore porosity increase gradually.> 100 microns ventilation pore porosity is
highest, account for more than 99% of the total porosity. Vegetation restoration is
advantageous to the increase in long and narrow pore shape factor (0.2) or less porosity,
and lower irregular pore (0.2< shape factor < 0.5) and the rules of the pore porosity of
shape factor (0.5 or higher). Long, narrow pore porosity is highest, account for more than
99% of the total porosity. Soil silt content is the main influence factors of aggregate pore
structure characteristics, and 1-5 mm irregular porosity in the aggregate, rules, porosity
and capillary porosity significantly negative correlation (Sig) < 0.001).
4. Process of returning cultivated land to grassland significantly improves the
performance of soil water and holding water. As the vegetation restoration, soil saturated
hydraulic conductivity from the conversion of 4.16 mm·min -1 , 3 years to grain for 22
years of 6.74 mm·min -1 , significantly increased by 61.9%.Compared with the slope,  when the organic carbon content and water stability of large aggregate content increase 1
g·kg -1 and 1% respectively, the saturated hydraulic conductivity increased by 1.2% and
2.4%, respectively. Vegetation restoration is helpful to improve the soil water-holding
capacity, mainly reflected in the 0 to 10 cm soil layer, the conversion of 22-24 years
water-holding performance improved significantly. Large aggregate stability of soil water
content and organic carbon content are the main factors influencing the saturated
hydraulic conductivity, and organic carbon content is the most important factors affect
the ability of the soil moisture. Organic carbon content increase large aggregate stability
by increasing the water content to improve soil structure, thus improve the saturated
hydraulic conductivity and water holding capacity.
5. Returning farmland to grassland could improve the ability of soil, rainfall
infiltration. Show the with vegetation restoration, the initial infiltration rate increase,
extend the time of reach the steady infiltration rate. In the process of vegetation
restoration infiltration rate increased with the increase of rainfall intensity.1-5 mm
aggregate irregular porosity and capillary porosity are the main factors influencing the
initial infiltration rate, and negatively correlated with the initial infiltration rate.
Moderate rain is strong, the stable infiltration rate and 2-1 mm aggregate negatively
correlated with irregular porosity. Heavy rain is strong, the stable infiltration rate and 5-2
mm long and narrow porosity aggregate were positively correlated.
Key words: returning farmland to grassland; soil structure; micro-CT; soil
hydraulic properties; rainfall infiltration