摘要
【目的】准确量化半干旱区典型人工林的蒸腾特征及其对气象因子和土壤水分的响应规律,探究其水分利用策略的差异,为该区域的林水综合管理提供理论依据。【方法】2022年5—10月,在六盘山半干旱区叠叠沟小流域选取当地主要的造林树种华北落叶松和白桦,各布设1个面积30 m×30 m的固定样地,每个样地选取12株不同胸径的样树,连续测定树干液流密度、气象因子和0~60 cm土层的土壤含水量,分析华北落叶松和白桦人工林蒸腾特征及其对潜在蒸散(PET)和土壤相对可利用水分(REW)的响应差异。【结果】1)7—10月华北落叶松和白桦人工林的日均蒸腾量分别为0.63和0.54 mm·d^(-1),前者比后者高0.09 mm·d^(-1);华北落叶松和白桦林分日蒸腾量随着月份变化均呈先增后减的变化趋势,在7月均达到最大值,分别为1.38和1.45 mm·d^(-1)。2)2种人工林的日蒸腾量对PET的响应均符合指数函数关系,即日蒸腾量随PET增大呈先增大后趋于稳定,但变化趋势在不同REW之间有差别;华北落叶松林分日蒸腾量随PET增长的速率在REW<0.3时较低,在REW>0.3后则迅速升高,且不同REW之间差距很小;而白桦林分日蒸腾量随PET增长的速率持续增大,且比较均匀。3)2种人工林的日蒸腾量对REW的响应也均符合指数函数关系,但变化趋势在不同PET之间有差别;华北落叶松林分蒸腾量随REW增长的速率在PET<2 mm·d^(-1)时较低,在PET>2 mm·d^(-1)后则迅速升高,且不同PET之间差距很小;相比之下,白桦人工林日蒸腾量随REW增大而升高的变化在整个PET变化范围内都比较均匀,且增长速率持续增大。【结论】华北落叶松林分日蒸腾量对PET和REW的响应明显比白桦林更敏感。华北落叶松林分日蒸腾量在PET<2 mm·d^(-1)或REW<0.3时明显高于白桦,但在PET>2 mm·d^(-1)或REW>0.3后迅速升高到其最大值附近并随PET或REW升高保持稳定,而白桦林分日蒸腾量表现为相对均匀地逐渐趋于其最大值。这说明在水分受限的半干旱区,华北落叶松林的蒸腾耗水量高于白桦林,且白桦林蒸腾受干旱期土壤水分的限制更明显。
【Objective】This study aims to accurately quantify the transpiration characteristics of typical plantations in the semiarid area and their response to meteorological factors and soil moisture,and to explore the differences in water use strategies among tree species,so as to provide a theoretical basis for integrated forest-water management in this area.【Method】From May to October in 2022,the plantations of main afforestation tree species of Larix principis-rupprechtii and Betula platyphylla were selected for this study in the small watershed of Diediegou in the semi-arid area of Liupan Mountains.A fixed sample plot was set up for each type of plantation with the size of 30 m×30 m.A total of 12 sample trees with different diameters at breath height(DBH)in each plot were chosen for monitoring the sap flow density of trunk.Meanwhile,the meteorological parameters and soil moisture of 0–60 cm soil layers were measured continuously.The differences in transpiration response of the two plantations to the daily potential evapotranspiration(PET)and relative extractable soil water(REW)were analyzed.【Result】1)From July to October,the daily transpiration of L.principis-rupprechtii and B.platyphylla plantations was 0.63 and 0.54 mm·d^(-1),respectively,with the transpiration for the former being 0.09 mm·d^(-1) higher than that for the latter.The daily transpiration of both plantations firstly increased and then decreased with changing month,and reached their maximum values in July,at 1.38 and 1.45 mm·d^(-1),respectively.2)The responses of daily transpiration of both plantations to PET exhibited an exponential function relationship,that is,the daily transpiration increased gradually with rising PET and finally tended to be stable,but the response trends were different among different REW levels.The increase rate of daily transpiration of L.principis-rupprechtii plantation with rising PET was relatively low when the REW was<0.3,and rapidly increased after the REW was>0.3,but the difference in the rates among REW levels was small.In contrast,the daily transpiration of B.platyphylla plantation continued to increase at a relatively uniform rate with rising PET in the whole variation range of REW.3)The responses of daily transpiration of both plantations to REW also followed an exponential function relationship.However,there was a significant difference in the response trend of daily transpiration between the two plantations,that is,the increase rate of daily transpiration of L.principis-rupprechtii plantation increased with rising REW was low when PET<2 mm·d^(-1),but it rapidly increased when PET>2 mm·d^(-1),and showed little difference among the PET levels.In contrast,the increase rate of daily transpiration of B.platyphylla plantation with rising REW was more uniform and showed a continuous increase in the whole variation range of PET.【Conclusion】The response of daily transpiration of L.principis-rupprechtii plantation to PET and REW is more sensitive than that of B.platyphylla plantation to PET and REW.When PET<2 mm·d^(-1) or REW<0.3,the daily transpiration of L.principis-rupprechtii plantation is significantly higher than that of B.platyphylla plantation.When PET>2 mm·d^(-1) or REW>0.3,the daily transpiration of L.principis-rupprechtii plantation increases rapidly to its maximum and then remains stable with the increase of PET or REW,while the daily evapotranspiration of B.platyphylla plantation tends to its maximum in a relatively uniform manner.Therefore,in the semi-arid areas with limited water,the water consumption for the transpiration of L.principis-rupprechtii plantation is higher than that of B.platyphylla plantation,and the transpiration of B.platyphylla plantation is more obviously restricted by the soil drought stress.
作者
张智伟
万艳芳
于澎涛
白雨诗
王彦辉
刘兵兵
王晓
胡振华
Zhang Zhiwei;Wan Yanfang;Yu Pengtao;Bai Yushi;Wang Yanhui;Liu Bingbing;Wang Xiao;Hu Zhenhua(College of Forestry,Shanxi Agricultural University Jinzhong 030801;Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration Ecology and Nature Conservation Institute,Chinese Academy of Forestry Beijing 100091)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2024年第10期29-39,共11页
Scientia Silvae Sinicae
基金
国家自然科学基金项目(U21A2005,U20A2085,42161144008,41971038,32171559)。
关键词
蒸腾
土壤水分
潜在蒸散
华北落叶松
白桦
transpiration
soil water
potential evapotranspiration
Larix principis-rupprechtii plantations
Betula platyphylla plantations
