干旱区梭梭茎干液流特性及对土壤水分的响应

Stem sap flowing characteristics of Haloxylon Ammodendron and its response to soil moisture in arid area

研究荒漠植物耗水特征及其与土壤水分的关系,分析维持荒漠植物生长的潜在水源,对提高干旱区用水效率,保证荒漠生态环境的安全具有重要意义。以新疆干旱区荒漠植被梭梭为研究对象,采用热扩散法研究其茎干液流特性,采用中子仪测定和烘干法相结合的方法测定土壤含水率,并分析了茎干液流与土壤水分的响应关系。结果表明:梭梭的茎干液流密度呈明显昼夜变化,日间液流密度明显高于夜间,且随着胸径的增大,日间液流密度减小;土壤含水率随土层深度的增加呈倒"S"型分布,5~8月土壤含水率逐渐减小,中间土层含水率随时间推移减小幅度显著;随着土壤含水率的降低,夜间液流密度基本保持不变,但日间液流密度的峰值明显减小。分析结果可为提高干旱区用水效率,保证西部生态环境的安全提供理论支撑。

Studying the relationship between water consumption characteristics of eremophyte and soil moisture and analyzing the potential water source that support the growth of eremphyte are of great significance to improving water utilization efficiency and providing a safe ecological environment.Taking haloxylon ammodendrune in arid area of Xinjiang as example,through studying the characteristics of stem sap flowing by thermal diffusion method and measuring the soil moisture by a combination of neutron meter and oven-drying method,the responsive relationship between stem sap flowing and soil moisture is analyzed.The results show that evident diurnal change exists in the density of stem sap flow with much higher density during daytime,and with the increase of the stem diameter,the flow density tends to decrease;distribution of soil moisture content appears a reverse“S”shape going deeper into the soil,and there is a gradual reduction in the soil moisture content from May to August,especially the water in the middle layer decreases significantly with time;as water content declines,density of stem sap flow at night remains roughly constant,but showing a quite obvious reduction of peak at daytime.