宁南黄土丘陵区3种典型林分的结构与水文影响比较

为分析宁南黄土丘陵区林分结构的水文功能影响关系及差异,以彭阳县3种典型林分(山杏纯林、山杏柠条混交林、山杏沙棘混交林)为对象,在2017年生长季观测了林下草本生物量和生物多样性、冠层降雨再分配、林下蒸散、土壤湿度的变化特征。结果表明:(1)林分地表覆盖度大小顺序为山杏沙棘混交林(0.81)山杏柠条混交林(0.71)山杏纯林(0.67);草本植物地上生物量为山杏沙棘混交林(0.86)山杏纯林(0.62)山杏柠条混交林(0.41);草本植物生物多样性为山杏柠条混交林山杏沙棘混交林山杏纯林。(2)3种林分类型的冠层都相对稀疏,降雨穿透率均90%,穿透雨量与林外降雨呈线性正相关;干流量和林冠截留量与林外降雨呈对数关系。(3)林下蒸散的季节变化呈"单峰型",研究期间林下蒸散表现为山杏沙棘混交林(245.0mm)山杏纯林(227.7mm)山杏柠条混交林(220.9mm),其中山杏柠条混交林的月际间差异最小。(4)生长季内土壤湿度在中上层(0—80cm)表现为逐渐降低趋势,在深层则相反;深层土壤水分的林分差异为山杏纯林山杏沙棘混交林山杏柠条混交林。在干旱缺水、侵蚀严重的黄土区,要恢复以水土保持为主要功能的稳定植被时,既要考虑植被配置模式对地表覆盖和草本生物量及物种多样性的影响,也要考虑对土壤湿度的影响,因此建议在植被恢复中尽量选择山杏沙棘混交林和山杏纯林。

Comparison of Structure and Hydrological Influence of Three Typical Stands in Loess Hilly Regions of Southern Ningxia

In order to analyze the relationship and difference of hydrological function of the stands structure in the loess hilly regions of southern Ningxia, the characteristics of understory herb biomass and biodiversity, canopy rainfall redistribution, forest understory evapotranspiration and soil moisture were studied in three typical forest stands (Armeniaca sibirica pure forest, Armenia sibirica-Caragana korshinskii mixed forest, Armeniaca sibirica-Hippophae rhamnoides mixed mixed forest)located in Pengyang County during the growing season in 2017. The results were as follows:(1) The order of stands surface coverage was A.sibirica-H.rhamnoides (0.81) > A.sibirica-C.korshinskii (0.71) > A.sibirica (0.67), the aboveground biomass of herbaceous plants followed the order of A.sibirica- H.rhamnoides (0.86 t/hm²) > A. sibirica(0.62 t/hm²) > A. sibirica-C. korshinskii(0.41 t/hm²), and the herbaceous plant biodiversity was followed the order of A.sibirica-C.korshinskii > A.sibirica-H.rhamnoides > A.sibirica. (2) The canopies of the three stands were relatively sparse, and the rainfall penetration rate were all greater than 90%,and the penetration rainfall was linearly correlated with the rainfall outside the forest,the stemflow and the canopy interception were logarithmic related to the rainfall outside the forest. (3) The seasonal variation of forest understory evaoptranspiration was "single-peak type", and the size of forest understory evapotranspiration during the research period was followed the order of A.sibirica-H.rhamnoides (245.0 mm) > A.sibirica (227.7 mm) > A.sibirica-C.korshinskii (220.9 mm), among them, the intermonthly variation of A.sibirica-C.korshinskiiwas the minimum. (4) The soil moisture in the middle and upper layers (0-80 cm) basically showed decreasing trend during the growing season, while the deep soil moisture showed the opposite trend, and the difference in the deep soil moisture was showed as A.sibirica > A.sibirica-H.rhamnoides > A.sibirica-C.korshinskii.In the severe erosion and drought-stricken loess region, when restoring stable vegetation with water and soil conservation as the main function, it was necessary to consider the effects of vegetation allocation patterns on surface cover and herb biomass and species diversity, as well as to consider the effect on soil moisture.Therefore, it is recommended to choose A.sibirica-H.rhamnoides mixed forest and A.sibiricapure forest in the vegetation restoration.