摘要
近年来为防治黄土高原水土流失,我国政府开展了一系列的植被恢复工作。了解造林植被水分利用策略,对于在干旱半干旱黄土高原地区开展有效的植被恢复至关重要。以黄土高原甘肃省定西市安家沟小流域为研究区,选取黄土高原大规模植树造林灌木柠条(Caragana korshinskii)和沙棘(Hippophae rhamnoides)为研究对象,利用包裹式液流计于2020年6—9月对柠条和沙棘树干和枝条的液流进行观测,研究柠条和沙棘树干液流密度的日内与年内变化,以及与环境要素的关系。结果表明,柠条与沙棘的液流密度日内变化规律与光合有效辐射(Q_(0))、饱和水汽压差(D_(z))变化趋势一致。液流密度对环境要素的响应不同,在8月份,柠条和沙棘液流密度受D_(z)、Q_(0)和气温(T_(a))的影响较大,其中,D_(z)占主导地位。在其他月份,液流密度主要受D_(z)、Q_(0)的影响较大。当柠条与沙棘经历了长期干旱无雨的条件下,土壤含水量对树干液流的影响较大,D_(z)和Q_(0)已不再是影响树干液流密度的主要因素。在降雨过后的阴天,树干液流仍保持较大的密度,这是由于在半干旱地区植被生长长期受土壤水分胁迫,降雨补给了土壤水分,对树干液流密度存在脉冲效应。
In recent years, the Chinese government has carried out a series of vegetation restoration work to prevent soil erosion on the Loess Plateau. Understanding the water use strategy of afforestation vegetation is very important for effective vegetation restoration in arid and semi-arid Loess Plateau region. However, unreasonable afforestation activities cause damage to soil moisture environment, resulting in low survival rate, low preservation rate and low comprehensive benefit of vegetation. The key to the problem lies in the use of water consumption strategy in the process of vegetation restoration. In this study, Caragana Korshinskii and Hippophae rhamnoides were were selected as the research objects for large-scale afforestation in Anjiagou small watershed of Dingxi City, Gansu Province. We measured sap flow in the branches and stems of shrubs using sap flow gauges(Flow32, Dynamax Inc., Houston, TX, USA), and studied the response of sap flow density to the environment factors. The results showed that the effect of rainfall on water content in 10 cm soil layer was more obvious than that in the other three soil layers. Soil water content and coefficient of variation were relatively low in deeper layers. The soil water content in 10 cm soil layer responded to rainfall events with accumulated rainfall over 10—12 mm in 3—5 days. For the soil depth of 20, 30, 40 cm and 50 cm, a single rainfall less than 10 mm had little effect on soil water content. The average daily sap flow densities of C. korshinskii and H. rhamnoides were 1553 kg m^(-2)d^(-1)and 1760 kg m^(-2)d^(-1), respectively. In most cases, higher sap flow densities were consistent with higher values for Q_(0)and D_(z). For example, on 30thJune and 15thJuly, the sap flow densities of C. korshinskii and H. rhamnoides were 3129.88 and 2772.81 kg m^(-2)d^(-1)and 3264.04 and 3234.32 kg m^(-2)d^(-1), respectively. For example, on 14thJune and 5thSeptember, the sap flow densities of C. korshinskii and H. rhamnoides were 923.11、1140.24 kg m^(-2)d^(-1)and 552.15、571.24 kg m^(-2)d^(-1), respectively. In the period of rainfall, the decrease range of sap flow densities becomes higher. There were different responses of sap flow density to weather conditions. Sap flow density in C. korshinskii and H. rhamnoides was the result of the vapour pressure deficit, photosynthetically active radiation and air temperature in August, and the sap flow density mainly depended on the vapour pressure deficit. But the sap flow density was the result of the vapour pressure deficit and photosynthetically active radiation in other months. When C. korshinskii and H. rhamnoides experienced long-term drought and no rain, soil moisture content had a great influence on sap flow, and D_(z)and Q_(0)were no longer the main factors affecting sap flow density. On cloudy days after rainfall, sap flow still maintained a large density, which was due to the long-term soil water stress of vegetation growth in semi-arid areas. Rainfall enhanced soil water and had a pulse effect on sap flow density. The density of sap flow of H. rhamnoides is higher than that of C. korshinskii, which reflects that H. rhamnoides consumes more water under the same rainfall condition. As for the two shrubs, C. korshinskii has more advantages in vegetation restoration on the Loess Plateau. This study can provide necessary scientific basis for vegetation restoration on the Loess Plateau.
作者
孛永明
王丽洁
荐圣淇
BO Yongming;WANG Lijie;JIAN Shengqi(Research Institute of Soil and Water Conservation,Dingxi 743000,China;College of Water Conservancy Science&Engineering,Zhengzhou University,Zhengzhou 450001,China)
出处
《生态学报》
CAS
CSCD
北大核心
2023年第4期1553-1562,共10页
Acta Ecologica Sinica
基金
河南省自然科学基金项目(212300410413)
定西市科技计划项目(DX2020N12)。
关键词
树干液流
气象因子
柠条
沙棘
黄土高原
sap flow
environmental factors
C.korshinskii
H.rhamnoides
theLoess Plateau
