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首页> 外文期刊>Agricultural and Forest Meteorology >Radial pattern of sap flow and response to microclimate and soil moisture in Qinghai spruce (Picea crassifolia) in the upper Heihe River Basin of arid northwestern China
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Radial pattern of sap flow and response to microclimate and soil moisture in Qinghai spruce (Picea crassifolia) in the upper Heihe River Basin of arid northwestern China

机译：西北干旱黑河上游流域青海云杉（Picea crassifolia）的树液径流模式及其对小气候和土壤水分的响应

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摘要

In order to accurately estimate whole-tree water use and individual tree transpiration, it is important to have reliable information on radial patterns of sap velocity and responses of sap flow to local environmental conditions. Therefore, variation in sap flow and environmental conditions was investigated in a mature Qinghai spruce (Picea crassifolia) stands during the growing season of 201 1 at the Pailougou watershed, in Qilianshan Mountain, located in the upper Heihe River Basin, in the arid region of Northwest China. Daily sap flow was measured by the heat-pulse technique on nine trees during the growing season. It was found that the highest daily sap flow velocity in sap flow radial distribution was at 20 mm sapwood depth, and that from 10 mm to 20 mm sapwood depth, the daily sap flow velocity gradually increased, whereas from 20 mm to 40 mm sapwood depth, sap flow velocity gradually diminished. A simple Gaussian regression model for the radial distribution of sap flux velocity was formulated, which explained 92% of the radial profile variation of sap flow velocity. Sap flow velocity was heightened by increasing the global short-wave radiation (R, W m(-2)), vapour pressure deficit (D, kPa), and air temperature (T, degrees C) when R < 800 W m(-2), D < 1.4 kPa, and T < 18.0 degrees C. It is, however, inherently difficult to establish firm relationships between sap flow velocity and R, D, and T because of the complex crown environment. The correlation of daily sap flow velocity to soil moisture content on a clear day was fitted by a logistic regression. We conclude that measurement of radial flow pattern provides a reliable method of integrating sap flow from individual measuring points to the whole tree. And D, R, T and soil moisture had varying influences on sap flow velocity in the Qinghai Spruce
机译：为了准确估计整棵树的用水量和单棵树的蒸腾作用，重要的是要掌握有关树液速度的径向模式和树液流量对当地环境条件的响应的可靠信息。因此，在黑河上游干旱地区祁连山白露沟流域201 1生长期的青海云杉（Picea crassifolia）生长期中，研究了其汁液流量和环境条件的变化。中国西北。在生长季节，通过热脉冲技术对九棵树上的树液流量进行了测量。研究发现，沿树液流径向分布的最高日树液流速在边材深度为20 mm时，从10 mm到20 mm边材深度，日树液流速逐渐增加，而从20 mm到40 mm边材深度。 ，汁液流速逐渐减小。建立了一个简单的高斯回归模型，用于树汁通量速度的径向分布，解释了树汁流速径向分布的92％。当R <800 W m（-）时，通过增加整体短波辐射（R，W m（-2）），蒸气压赤字（D，kPa）和气温（T，摄氏度）来提高树液流速。 2），D <1.4 kPa，T <18.0摄氏度。但是，由于复杂的冠状环境，固有地很难在树液流速与R，D和T之间建立牢固的关系。通过logistic回归拟合晴天时树液日流速与土壤含水量的相关性。我们得出的结论是，径向流向的测量提供了一种可靠的方法，可将树液从单个测量点流向整棵树。而D，R，T和土壤水分对青海云杉汁液流速具有不同的影响

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