不同营林措施对川东华蓥山杉木林土壤团聚体稳定性及细根分布的影响

Effects of Forest Management Measurements on Soil Aggregate Stability and Fine Root Distribution of Chinese Fir in Huaying Mountains of East Sichuan

[目的]探明不同营林措施对杉木(Cunninghamia lanceolata)人工林土壤团聚体稳定性及细根分布的影响。[方法]选取川东华蓥山杉木人工林为研究对象,以无处理样地为对照,对比分析间伐、除灌、套种香樟(Cinnamomum camphora)、凋落物去除4种营林措施下土壤团聚体稳定性及细根分布特征。[结果]不同营林措施中,间伐林各土层土壤大于0.25 mm粒径的机械稳定性团聚体含量和水稳性团聚体含量均为最高,各土层干筛、湿筛的土壤团聚体平均重量直径最大。相比对照,间伐林0~10 cm、10~20 cm和20~40 cm土层干筛的土壤团聚体平均重量直径分别显著增加46.76%、34.63%和43.78%(P <0.05),湿筛的土壤团聚体平均重量直径分别显著增加45.23%、70.11%和77.98%(P <0.05)。不同营林措施0~10 cm土层的细根根长密度和细根根质量密度显著高于其他土层(P <0.05)。随土层深度增加,细根根长密度和细根根质量密度均显著降低(P <0.05),0~10 cm土层套种香樟的细根根长密度和细根根质量密度最高。间伐、除灌后营林的根系大量补偿生长,细根根长密度和细根根质量密度较高。相关分析表明,不同营林措施下根系特性因子细根根长密度和细根根质量密度能显著改变> 0.25 mm团聚体含量,从而影响团聚体稳定性。[结论]间伐后杉木林土壤结构得到有效改善,团聚体稳定性最高,套种香樟、间伐后杉木林表土细根发达程度较高。因此,建议川东地区杉木人工林经营管理应优先考虑适度间伐。

[Objective]The aim of this study is to clarify the effects of different forest management measurements on soil aggregate stability and fine roots distribution in Chinese fir(Cunninghamia lanceolata)plantations.[Method]The plantation of Chinese fir in Huaying Mountains of East Sichuan was selected,and the untreated plots were used as control to compare and analyze soil aggregate stability and fine roots distribution characteristics after thinning,understory removal,intercropping with Cinnamomum camphora,and litter removal.[Result]Among the five forest management measurements in each soil layer,the percentages of>0.25 mm mechanicalstable aggregates(DR0.25)and water-stable aggregates(WR0.25)were the highest in the thinned forest,and the mean weight diameter(MWD)of dry sieving and wet sieving of each soil layer were also the highest.Compared with the control,the MWD of dry sieving of each soil layer of thinned forest increased significantly(P<0.05)by 46.76%,34.63%and 43.78%,respectively,and the MWD of wet sieving of each soil layer of thinned forest increased significantly(P<0.05)by 45.23%,70.11%and 77.98%,respectively.The fine root length density(RLD)and the fine root mass density(RMD)of the five forest management measurements in the 0-10 cm soil layer were significantly higher than other soil layers(P<0.05).With the increase of soil depth,the RLD and RMD of the five forest management measurements were significantly decreased(P<0.05),the RLD and RMD of intercropping with Cinnamomum camphora in the 0-10 cm soil layer were the highest.The growth of fine root contributes to the increment of RLD and RMD after thinning and understory removal.The results of correlation analysis showed that the root characteristic factors RLD and RMD under forest management measurements can significantly alter the content of aggregates>0.25 mm,thereby influencing the stability of soil aggregates.[Conclusion]The soil structure of Chinese fir plantations improves effectively,and the aggregate stability of the soil is at its highest after thinning.The development degree of surface fine roots in Chinese fir plantations is higher after intercropping with Cinnamomum camphora and thinning.Therefore,it is recommended that moderate thinning should be given priority in the management of Chinese fir plantation in eastern Sichuan.