荒漠草原中间锦鸡儿(Caragana intermedia)冠层穿透雨的发生与分布特征

Occurrence and Distribution of Throughfall under Caragana intermedia Canopy in Desert Steppe

为进一步认识荒漠草原带状人工中间锦鸡儿林(Caragana intermedia)植被稳定性维持的生态水文过程机制,通过对行生和散生中间锦鸡儿冠层穿透雨的对比研究,结果表明:(1)两者对降水变化响应显著,但是差异不显著。散生和行生中间锦鸡儿穿透雨百分比变化范围分别为25.6%~96.5%(Cv=23%)和25.4%~96.1%(Cv=19%),穿透雨量均值分别为7.55 mm和7.40 mm。穿透雨量与降雨量、降雨历时、降雨强度都具有极显著的线性回归关系,但是穿透雨百分比与降水特征参数以幂函数关系为主。(2)冠层下穿透雨分布存在明显的空间异质性。穿透雨百分比普遍随距灌丛基部距离的增大而线性增大。"旱区"集中出现在散生中间锦鸡儿灌木的基部,向外百分比逐步提高;行生中间锦鸡儿则出现了多个旱区和雨极镶嵌分布的情况。

The rainfall redistribution through canopy is of important eco-hydrological significance for the survival of shrubs.The Caragana intermedia plantation in large area in desert steppe is mostly zonal,and the growth mode and morphological characteristics of natural sporadic C.intermedia plants are quite different.Whether this difference affecting the distribution of precipitation through canopy is necessary to be further verified.The eco-hydrological mechanism of vegetation stability of adult C.intermedia plantation in desert steppe should be further understood.The occurrence and distribution of throughfall under C.intermedia canopy in two different growth patterns(scattered and row distribution)were compared and analyzed by monitoring precipitation redistribution in 18 different rainfall events in 2016.The results showed that the throughfall percentage of scattered C.intermedia plants was25.6%-96.5%,that of row ones was 25.4%-96.1%,and the coefficients of variation was 23%and 19%respectively.The mean values of throughfall were similar and for 7.55 mm and 7.40 mm respectively.Rainfall,rainfall duration,and rainfall intensity had a very significant linear relationship with thoughfall depth,but the relationship between throughfall percentage and characteristic parameters of precipitation was complex,which was dominated by power function,and the fitting significance of scattered C.intermedia plants was better than that of row ones.The distribution of throughfall under canopy was spatial heterogeneity.Generally,throughfall percentage was increased linearly with the increase of distance from shrub base.The"dry area"of throughfall was concentrated at the base of scattered C.intermedia plants,however,the distribution of row ones was more complex.Mosaic distribution of dry areas and rain pole was found for row C.intermedia plants.The different growth patterns of C.intermedia plants did not significantly affect the throughfall depth,but the spatial distribution pattern of throughfall under canopy was significantly changed,which might further affect the process of the conversion from precipitation to soil water.