不同改造模式对柏木人工林土壤团聚体粒径分布及稳定性的影响

Effect of Different Transformation Modes on the Particle Size Distribution and Stability of Soil Agglomerates in Cypress Plantations

土壤团聚体是土壤结构的基本单元,对改善土壤质量和提升养分含量具有重要作用.为研究不同改造模式下川中丘陵区柏木人工林土壤团聚体特征,以绵阳市盐亭县林山乡柏木人工林为研究对象,基于干筛法和湿筛法比较分析疏伐改造(ET)、林窗改造(FG)、林带改造(SF)和柏木纯林(PC)4种模式0~40 cm土层深度下土壤团聚体粒径分布特征和稳定性指标.结果表明:(1)在干筛处理下,4种模式的柏木人工林土壤机械性团聚体以>2 mm为主,含量为48.07%~74.74%,而0~20 cm土层表现为疏伐改造显著高于林带改造,20~40 cm土层表现为柏木纯林显著高于林窗改造和林带改造.(2)在湿筛处理下,0~20 cm土层>2 mm粒径土壤水稳性团聚体表现为林带改造显著高于柏木纯林与林窗改造,0.053~0.25 mm粒径团聚体表现为林窗改造显著高于疏伐改造与林带改造.(3)平均重量直径(MWD)和几何平均直径(GMD)0.56~1.77,土壤水稳性团聚体MWD和GMD在0~20 cm土层表现为疏伐改造显著高于林窗改造.这表明,改造模式能够显著影响柏木人工林土壤团聚体粒径分布和稳定性特征,本研究为川中丘陵区柏木人工林的经营管理提供基础数据.

Soil agglomerates are the basic units of soil structure and play an important role in improving soil quality and enhancing nutrient content.To study the characteristics of soil agglomerates in cypress plantations in the central Sichuan hilly area under different transformation modes,the soil agglomerate size distribution and stability indexes of cypress plantations in 0-40 cm soil depth were analyzed based on dry sieving method and wet sieving methods in comparison with four modes of plantation with ecological thinning(ET),plantation with natural gap(NG),plantation with strip filling(SF)and pure cypress plantation(PC)in Linshan Township,Yanting County,Mianyang City.The results showed that:(1)under the dry sieving method treatment,the mechanical soil agglomerates of cypress plantations in the four models were mainly>2 mm,with contents ranging from 48.07%to 74.74%,while the 0-20 cm soil layer showed significantly higher in the plantation with ecological thinning than the plantation with strip filling,and the 20-40 cm soil layer showed significantly higher in the pure cypress plantation than plantation with natural gap and the plantation with strip filling;(2)under the wet sieve method treatment,the soil water stability agglomerates of>2 mm particle size in the 0-20 cm soil layer were significantly higher in the plantation with strip filling than pure cypress plantation andplantation with natural gap,and the agglomerates of 0.053-0.25 mm particle size were significantly higher in the plantation with natural gap than the plantation with ecological thinning and the plantation with strip filling.(3)The mean weight diameter(MWD)and geometric mean diameter(GMD)ranged from 0.56-1.77,and the MWD and GMD of soil water stable agglomerates in the 0-20 cm soil layer was both significantly higher in the plantation with ecological thinning than the plantation with natural gap.This suggests that the transformation mode can significantly affect the particle size distribution and stability characteristics of soil agglomerates in cypress plantations,and this study provides basic data for the business management of cypress plantations in the central Sichuan hilly region.