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半干旱黄土丘陵区人工柠条林合理初植密度研究
宁 婷
Subtype硕士
Thesis Advisor郭忠升
2014-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword柠条 初植密度 生长 土壤水分 土壤水资源利用限度
Abstract

半干旱黄土丘陵区原生植被匮乏,水土流失严重。为尽快覆盖地表并迅速发挥水
土保持作用,该区人工林草种群的初植密度往往偏高。植被过载加速了林草地深层土
壤的干燥化进程,反过来严重干扰了植物的正常生长及其生态功能的稳定发挥。本研
究以人工柠条林为对象,通过比较不同初植密度柠条林的生长动态和林地土壤水分状
况,结合以林地土壤水资源利用限度为确定依据的植物水关系调控起始期理论,得到
了其合理初植密度。主要研究结论如下:
(1)研究区撂荒坡地降水普遍入渗深度为 0-40 cm,观测期内最大入渗深度不
超过 300 cm;土壤水分主要蒸散发作用层位于 0-200 cm 范围内,最大蒸散发深度在
300 cm 以下。整个土壤剖面水分可被划分为活跃层(0-40 cm)、次活跃层(40-200 cm)
和相对稳定层(200 cm 以下)三个层次。
(2)Gardner 幂函数方程对撂荒坡地各土层土壤水分特征曲线的拟合效果较佳。
方程中的参数 a、b 以及由方程推求的各水分常数均表现出先减少后增加的垂直变化
规律。土壤的持水和供水能力以 0-40 cm 和 240-400 cm 土层较强,中间土层较弱。
本区土壤水资源利用限度等于 0-290 cm 范围内各土层土壤含水量降至凋萎系数时的
土壤水资源量,为 222.84 mm。
(3)随着初植密度的增加,柠条幼林保存率、株高、基径均呈现先增加后减少
的单峰型变化,以 1.5 小区柠条保存率最高、长势最佳。另外,1-4 年生柠条生物量
随初植密度增加而增加,5 年生时,1.5 小区柠条生物量超过 2.0 小区。
(4)人工柠条林在增加次降水补给量的同时,也增加了林地土壤水分的消耗量
与利用深度,除在丰水年表现为对土壤储水量的正效应外,其他年份均表现为负效应。
造林后第 5 年,各密度柠条林地土壤水资源普遍接近或达到其利用限度。
(5)合理初植密度为既能充分利用土壤水资源,又不至于造成土壤过度干化,
确保植物能正常生长并发挥良好生态功能时的造林密度。本区人工柠条林播量以
0.015 kg·m -2 为宜,对应的合理初植密度为 72 株·m -2 ,且应于造林后第 5 年开始进行
密度调控。关键词 :柠条;初植密度;生长;土壤水分;土壤水资源利用限度

Other Abstract

The semi-arid Loess Hilly Region is characterized by the scarce native vegetation and
serious soil erosion. To cover ground quickly and play the role of conserving soil and water
as soon as possible, artificial forest and grass in this region are often planted with a too
high initial planting density. Overloaded vegetation accelerates the development of soil
desiccation in the deep soil layer, which in turn brings obviously negative effects on its
normal growth and stable ecological benefits. Therefore, this paper takes Caragana
korshinskii plantations as research objects, after discussing effects of initial planting
density on soil water conditions of forestland as well as growth dynamics of Caragana,
and applying the theory of initiation stage to regulate plant growth and soil water based on
soil water resources use limit (SWRUL), the suitable initial planting density is calculated.
Main conclusions draw from this study are as follows:
(1) The common depth of soil affected by rainfall infiltration in abandoned land is
0-40 cm, and the deepest infiltration depth is no more than 300 cm during the observation
period. Meanwhile, major depth that resulted from evapotranspiration (ET) is 0-200 cm,
and the deepest depth influenced by ET reaches 300 cm. The whole soil profile can be
divided into three levels, the active layer (0-40 cm), the second active layer (40-200 cm)
and the relatively stable layer (deeper than 200 cm).
(2) Soil water characteristic curves at different soil depth in abandoned land can be
well described by Gardner power function. Both parameters in the function and soil water
constants calculated from the function show vertical changing trends of first decrease then
rise. Soil water-holding capacity and water-supplying capacity in 80-200 cm soil layer are
weak compared with 0-40 cm and 240-400 cm soil layer. Besides, SWRUL in this region
can be estimated when soil water content in 0-290 cm soil layer are all smaller than their
corresponding wilting coefficient, and its value is 222.84 mm.  (3) The relationship between preserving rate, height, basic diameter and initial
planting density of Caragana can each be expressed as a single peak curve with the
greatest value appearing in the 1.5 plot. At the same time, biomass of Caragana aged from
1 to 4 years increases with the increase of initial planting density, but the biomass of 1.5
plot is more than that of 2.0 plot at age 5.
(4) Although Caragana plantation increases the recharge amount of precipitation, the
consumption and depletion depth of soil water are also increased. Thus there is a negative
effect of afforestation on soil water resources during the observation period (2002-2006),
with the exception of 2003 as it is a rainy year. Soil water resources of each plot have
generally been approached or reached the SWRUL at the fifth year.
(5) Suitable initial planting density can be defined as the planting density when not
only the use of soil water resources is maximized, but also excessive soil desiccation is
avoided, then artificial vegetation can grow normally with better ecological benefits. For
artificial Caragana forest, the fitting sowing amount is 0.015 kg· m -2 and the suitable
initial planting density is 72 plant·m -2 . This density should be regulated for the first time
after five years of afforestation.
Key words: Caragana korshinskii, initial planting density, growth, soil water, soil water
resources use limit

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8988
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
宁 婷. 半干旱黄土丘陵区人工柠条林合理初植密度研究[D]. 北京. 中国科学院研究生院,2014.
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