植物生长与土壤水关系调控起始期

Initiation stage to regulate the caragana growth and soil water in the semiarid area of Loess Hilly Region,China

确定植物生长与土壤水关系调控起始期是可持续利用土壤水资源的基础。以柠条为研究对象,采用中子仪对黄土丘陵半干旱区撂荒地,1～5年生柠条林生长和土壤水分进行长期定位观测和分析。结果表明:1 a内,随着时间推移,柠条利用土壤水分深度从播种时的表层土壤增加到220 cm;随着林龄增加,除丰水年2年生柠条林地土壤储水量增加外,柠条利用土壤水分深度和耗水量增加,林地土壤储水量下降。在2004年生长末期,3年生柠条林地100 cm土层的土壤含水量低于萎蔫系数,4年生柠条林地土壤旱化加剧,柠条生长与土壤水关系调控起始期是第5年。此时需要调控柠条生长与土壤水关系,采取措施降低柠条水分耗水量,实现土壤水资源可持续利用。

Determining initiation stage to regulate the plant growth and soil water is the base of sustainable use of soil water resources.In this paper,the dynamics of soil water were continuously measured with a neutron probe in fixed positions in the wasteland and newly sowing Caragana forest land during the period from 2002 to 2006 and the data measured was analysed.The results shows that the depth plant use soil water increases from the surface soil on 24th June to 220cm in the first year,and that the depth plant absorb and use soil water and soil water consumption increases,and the amount of soil water storage reduced with increasing age apart from the wet year in 2003 in which the amount of soil water storage increased by 122.8 mm at the 2-year-old Caragana forest land.It is also discovered that the soil water content at the soil layer of 100 cm is smaller than the wilting coefficient in the 3-year-old Caragana land and dried layer of soil become more and more serious in 4-year-old Caragana land and the initiation stage of regulating the relationship between Caragana growth and soil water is 5 years.Effective measures should be taken to control plant density and growth in order to realize sustainable use of soil water resources.