免炼山管理对桉树人工林土壤团聚体养分及稳定性的影响

王晔; 陈宗福; 黄康庭; 陈晓龙; 陈利军; 王亚琼; 柯琴; 吴立潮

doi:10.19336/j.cnki.trtb.2022032401

免炼山管理对桉树人工林土壤团聚体养分及稳定性的影响

Effects of Non-burning Management on Soil Aggregate Nutrients and Stability in Eucalyptus Plantations

摘要

摘要:
目的在中国南方桉树种植区，炼山作为传统的整地方式正加速桉树人工林土壤养分流失和土壤板结，而免炼山代替炼山可以改善桉树的生长环境并对土壤养分和结构产生积极影响。然而，从土壤团聚体角度来看，免炼山改良桉树人工林土壤结构和提升养分含量的原因仍不明确，需要深入探讨。
方法研究选取经过炼山和保留采伐剩余物两年后的桉树人工林为研究对象，并以当地常绿阔叶林作为对照，调查了两种林地管理方式下桉树人工林的平均胸径、平均树高和蓄积量，并进一步测定了所有林分中土壤团聚体（> 2 mm、2 ~ 0.25 mm、0.25 ~ 0.053 mm和 < 0.053 mm）的粒径分布及其有机碳、全氮和全磷含量。
结果相比于炼山，免炼山可以显著促进土壤的团聚化作用并提升各粒径团聚体中有机碳、全氮和全磷含量。相关性分析表明，2 ~ 0.25 mm和0.25 ~ 0.053 mm的土壤团聚体全氮、全磷含量与团聚体平均重量直径和几何平均直径呈显著的相关关系。主成分分析与线性回归分析进一步表明，土壤团聚体稳定性与桉树人工林平均胸径、平均树高和蓄积量显著正相关，且免炼山的土壤团聚体稳定性在两年时间已超过炼山，但短期内其表层土壤的团聚体稳定性状况仍无法达到常绿阔叶林的水平。
结论桉树免炼山造林可以提升各粒径土壤团聚体中有机碳、全氮和全磷含量，同时提升土壤团聚体稳定性并最终对桉树的生长产生积极影响。研究结果可为桉树人工林可持续经营过程中加强采伐剩余物的管理利用提供理论依据。

Abstract:
Objective Burning, as a traditional land preparation method, is accelerating soil nutrients loss and soil compaction in Eucalyptus plantations in southern China. Oppositely, replacing burning with non-burning can improve the growth environment of Eucalyptus and can have a positive impact on soil nutrients and structure. However, from the perspective of soil aggregates, the reasons for improving soil structure and nutrients content in Eucalyptus plantations with non-burning management remain unclear and need to be further explored.
Method In this study, Eucalyptus plantations after 2-year burning and retaining logging residues were selected as the research objects, and the local evergreen broad-leaved forest was used as the control. The average diameter at breast height, average tree height and volume of Eucalyptus under two different afforestation modes were investigated, and the particle size distribution of soil aggregates (> 2 mm, 2-0.25 mm, 0.25-0.053 mm and < 0.053 mm), the contents of organic carbon, total nitrogen, and total phosphorus in all stands were further determined.
Result Compared with burning, non-burning significantly promoted soil aggregation and increased the contents of organic carbon, total nitrogen and total phosphorus in aggregates of all different sizes. Correlation analysis showed that total nitrogen and total phosphorus in soil aggregates across 2-0.25 mm and 0.25-0.053 mm were significantly correlated with mean weight diameter and geometric mean diameter of aggregates. Principal component analysis and linear regression analysis showed that the soil aggregate stability was significantly positively correlated with the average diameter at breast height, average tree height and volume of Eucalyptus. Additionally, the soil aggregate stability of non-burning had far exceeded that of the traditional burning in two years, but in the surface soil it still could not reach the level of evergreen broad-leaved forest in the short term.
Conclusion Non-burning can improve the contents of organic carbon, total nitrogen and total phosphorus of soil aggregates in Eucalyptus plantations. It can also improve the soil aggregate stability, and ultimately has a positive impact on the growth of Eucalyptus. The results can provide a theoretical basis for strengthening the management and utilization of logging residues in the sustainable management of Eucalyptus plantations.

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