形态退化对中间锦鸡儿冠层茎流的影响

Effect of Morphological Degradation on Stem Flow in Canopy of Caragana intermedia

为深入认识降水分布与荒漠草原退化人工中间锦鸡儿林灌丛茎流发生的关系,选取实验样地人工种植的带状中间锦鸡儿林,以自然散生中间锦鸡儿群落的天然灌丛(健康组)和临近的典型退化灌丛(退化组)为研究对象,利用2016—2017年监测获取的23次中小降水事件下(0~15 mm)中间锦鸡儿茎流数据,开展了不同灌丛间茎流的差异性、茎流随降水变化的分布、茎流与降水特征值的回归关系等方面的研究。结果表明:(1)健康组和退化组树干茎流分别为14.42 mm和15.9 mm,树干茎流分别占总降雨量的8.06%和7.91%,二者间无显著差异。(2)随着雨量级的增大健康组和退化组的茎流量和茎流百分比均呈递增的趋势;健康组的茎流量和茎流百分比变异系数呈先减小后增大的趋势,退化组的茎流量和茎流百分比变异系数呈递减趋势。(3)健康和退化组的树干茎流量与降雨量,降雨历时和降雨强度的关系可以用一元线性函数拟合,茎流量百分比与降雨量,降雨历时和降雨强度的关系用对数函数拟合效果较好。总体而言,中间锦鸡儿存在明显的冠层茎流汇水效应,但是灌丛形态退化对茎流无显著影响。

In order to deeply understand the relationship between precipitation distribution and the occurrence of stem flow in shrub of Caragana intermedia forest in degraded desert steppe,selection of Caragana intermedia banded forest planted in experimental plot,the natural thickets(healthy group)and adjacent typical degraded thickets(degenerated group)of Caragana intermedia community were taken as the research objects,based on the stem flow data of small and meso-scale precipitation events(0~15 mm)obtained from 2016 to 2017,the typical degraded shrubs(degraded group)and the natural scattered Caragana intermedia(healthy group)in desert steppe were selected,the differences in stem flow of different shrubs,the distribution of stem flow with precipitation,and the regression relationship between stem flow and precipitation characteristics were analyzed.The results showed that:(1)the stem flows of healthy and degraded groups were 14.42 mm and 15.9 mm,respectively,trunk and stem flow accounted for 8.06%and 7.91%of the total rainfall,respectively,and there was no significant difference between them;(2)as the rainfall level increased,the stem flow and stem flow percentage of the healthy group and the degraded group showed an increasing trend;in the healthy group,the variation coefficient of stem flow and stem flow percentage decreased first and increased later,while the variation coefficient of stem flow and stem flow percentage decreased in the degraded group;(3)the relationship between stem flow and rainfall,rainfall duration and rainfall intensity in healthy and degraded groups can be fitted with a linear function,and the relationship between stem flow percentage and rainfall,rainfall duration and rainfall intensity can be fitted with logarithmic function.In general,the significant water confluence effect in the middle Caragana intermedia was observed,but no significant effect on the stem flow was found due to the morphological degeneration of shrubs.