川西亚高山针叶林次生演替对土壤持水量的影响

Effect of secondary succession on the soil water holding capacity of subalpine coniferous forest in western Sichuan,China

次生演替已成为川西亚高山针叶林迹地上的主要演替方式之一.选择川西米亚罗林区现有次生演替序列草地、灌丛、次生桦木林、原始针叶林为对象,研究川西亚高山森林采伐迹地次生演替过程中土壤物理性质以及持水性能的变化规律.结果显示,草地、灌丛和次生桦木林与原始针叶林相比,土壤容重差异性显著,分别增加了52.17%、44.93%、17.39%,土壤总孔隙度和非毛管孔隙度差异性显著,分别减少了13.61%、11.60%、4.66%和14.44%、12.62%、0.52%;关于土壤持水性能,原始针叶林有着最高的土壤最大持水量和土壤非毛管持水量,分别为2315.44 t/hm^(2)和751.40 t/hm^(2),随着次生演替进行,土壤非毛管持水量显著增加,细根和土壤有机质是导致土壤持水量变化的原因之一.综上所述,较之原始针叶林,其他3种演替阶段的土壤蓄水能力都遭到了不同程度的破坏.前期采伐破坏了土壤物理结构,土壤仍留有"记忆",叠加上后期干扰,改变了土壤物理性质,使其具有较高的土壤容重和较低的土壤总孔隙度,因而土壤持水性能相对较差.上述研究可为加快川西亚高山针叶林迹地生态功能恢复提供科学依据.

The secondary succession of subalpine forests in western Sichuan has become one of the main succession modes in this region.However,few studies have focused on the physical properties and water retention of soil in the succession environment in this region.Grasslands,shrublands,secondary birch forests,and primitive coniferous forests in the Miyaluo forest area of western Sichuan were selected as the research objects to reveal the change pattern of soil physical properties and soil water holding performance during secondary succession.The results showed that the soil bulk density of grassland,shrubland,and secondary birch forest increased significantly by 52.17%,44.93%,and 17.39%,respectively,compared with the primitive coniferous forest,whereas the total soil porosity and non-capillary porosity decreased significantly by 13.61%,11.60%,and 4.66%,and 14.44%,12.62%,and 0.52%,respectively.In terms of soil water holding capacity,the primitive coniferous forest stage had the highest soil maximum water holding capacity and non-capillary water holding capacity of 2315.44 and 751.40 t/hm^(2),respectively;the non-capillary water holding capacity of the soil increased significantly with secondary succession,and fine roots and soil organic matter contributed to the change in soil water holding capacity.These results revealed that,compared with the primitive coniferous forest,the soil water storage capacity of the other three succession stages was damaged to varying degrees.Early logging destroyed the physical structure of the soil and the soil"memory"was superposed with the disturbance,which changed the physical properties of the soil and increased the soil bulk density and lowered soil total porosity.Therefore,the soil water holding capacity was relatively poor.These results have theoretical and practical significance for accelerating the restoration of the ecological function of subalpine coniferous forests in western Sichuan.