红壤丘陵区3种林分土壤颗粒粒级分布特征及其对养分含量的影响

Soil Particle Characteristics of Three Forest Stands in Red Soil Hilly Areas and Their Effects on Nutrients

【目的】探究红壤丘陵区不同林分林下土壤颗粒粒级分布特征和土壤养分含量,为该地区林分升级、土壤肥力改善和纯林可持续经营提供理论依据。【方法】以红壤丘陵区3种典型林分林下土壤作为研究对象,运用相关性分析和逐步回归分析探讨不同林分类型土壤颗粒粒级分布特征、分形维数及其与土壤养分含量的相互关系。【结果】①3种林分土壤质地类型主要集中在粉壤土、粉土和砂壤土,3种林分分形维数的大小为:桉树×红锥混交林>桉树纯林>红锥纯林。②除土壤全磷以外,不同林分类型和土层均对土壤养分含量具有显著性影响(P<0.05),尤其混交林中更为明显。但两者之间的交互作用仅对有机质、全氮和全钾具有显著性影响(P<0.05),而对pH和全磷无显著影响。③土壤颗粒分形维数与黏粒含量呈极显著正相关,与土壤粉粒、有机质和全氮的含量呈显著负相关性(P<0.05),同时土壤颗粒分形维数与黏粒、粉粒、极细砂、全氮和全钾呈极显著线性相关性(P<0.001)。【结论】土壤颗粒的分形特征可以在一定程度上反映不同林分类型土壤颗粒粒级分布特征及其养分含量,而混交林较纯林土壤分形维数和养分含量均高于纯林,混交林较纯林具有更优越的保水保土功能和更高的土壤肥力水平。

[Objective]The aim was to explore the soil particle distribution characteristics and soil nutrient properties in different forest stands in the red soil hilly area,in order to provide a theoretical basis for forest stand upgrading,soil fertility improvement and sustainable management of pure forests in the region.[Method]Three typical forest understory soils in red soil hilly areas were used as research objects,and correlation analysis and stepwise regression analysis were applied to explore the particle composition,fractal dimension and their interrelationships with soil nutrients in different forest types.[Result]①The soil textures of the three forest stands in this study area were mainly concentrated in silt loam,silt and sandy loam.The fractal dimension of the three stands was:eucalyptus×red cone mixed forest>eucalyptus pure forest>red cone pure forest.②Except for total soil phosphorus,the different stand types and soil layers had significant effects(P<0.05)on soil nutrient content,especially in mixed forests.However,the reciprocal action between stand types and soil layers only had significant effects(P<0.05)on organic matter,total nitrogen and total potassium,and had no significant effects on pH and total phosphorus.③Soil particle fractal dimension was highly significantly positively correlated with clay particle content and negatively correlated with soil meal,organic matter and total nitrogen content(P<0.05),while soil particle fractal dimension was highly significantly linearly correlated with clay,meal,very fine sand,total nitrogen and total potassium(P<0.001).[Conclusion]The fractal characteristics of soil particles could reflect the distribution characteristics of soil particles and their nutrient contents in different forest types,and the soil fractal dimension and nutrient contents of mixed forests were higher than those of pure forests.So mixed forests had better water,soil retention functions and higher soil fertility quality levels than pure forests.