竹林扩张进入杉木人工林对土壤磷素的影响

Effects of bamboo forest expansion on soil phosphorus in Cunninghamia lanceolata plantation

【目的】揭示毛竹林扩张进入周边杉木林引起磷素的动态变化,为杉木林的管理提出合理建议。【方法】采用Hedley磷素分级研究毛竹林扩张进入杉木人工林土壤磷素的变化特征。【结果】竹林扩张进入杉木林的过程显著改变了林地土壤无机磷、有机磷和残余磷的组成。30%竹林与70%杉木混交林总无机磷、总有机磷和总磷含量均显著高于其他立地林;纯杉木林残余磷含量显著高于其他立地林。竹林扩张进入杉木林的过程显著改变了林地土壤磷酸酶含量(P <0.05)。竹林扩张进入杉木林的过程中各个阶段土壤样本提取的DNA中,Pho C基因丰度均显著高于Pho D基因丰度。竹林扩张对磷酸酶、有机磷和无机磷均产生了负面影响。根据方差分析和结构方程模型分析,竹林扩张进程直接和间接驱动土壤磷酸酶、有机磷和无机磷的变化,主要是通过影响土壤磷酸酶而影响土壤有机磷,而土壤有机磷又驱动土壤无机磷变化,卡方检验MIN/DF=3.759 <5,各标准化路径系数均显著(P <0.05)。【结论】有机磷在纯杉木人工林中是稳定的,当竹林扩张进入杉木林时需择时进行干预。

【Objective】This study revealed the dynamic changes of phosphorus caused by the expansion of bamboo forests to surrounding Cunninghamia lanceolata forests and provided reasonable suggestions for the management of Cunninghamia lanceolata forests.【Method】In this study,Hedley phosphorus classification was used to study the variation characteristics of soil phosphorus in the expansion of Phyllostachys pubescens into Cunninghamia lanceolata plantations.【Result】The process of bamboo forest expansion into Cunninghamia lanceolata forest significantly changed the composition of inorganic phosphorus,organic phosphorus and residual phosphorus in the soil.The contents of total inorganic phosphorus,total organic phosphorus and total phosphorus in the mixed forest of 30%bamboo and 70%Cunninghamia lanceolata were significantly higher than those in other forests.The residual phosphorus content in pure Cunninghamia lanceolata forest was significantly higher than that of other forests.The process of bamboo forest expansion into Cunninghamia lanceolata forest significantly changed the soil phosphatase content(P<0.05).The abundance of PhoC was significantly higher than PhoD in the DNA extracted from the soil samples at each stage during the expansion of bamboo forest into Cunninghamia lanceolata forest.Bamboo forest expansion had negative effects on phosphatases,organic phosphorus and inorganic phosphorus.According to variance analysis and structural equation model analysis,the bamboo forest expansion process,directly and indirectly,drove the changes of soil phosphatase,organic phosphorus and inorganic phosphorus,mainly by influencing soil phosphatase and soil organophosphorus,which in turn drove the changes of soil inorganic phosphorus.The change in the overall model fit the data(Chi-square test MIN/DF=3.759<5),and each standardized path coefficient was significant(P<0.05).【Conclusion】Organophosphorus is stable in pure Cunninghamia lanceolata plantation.This study shows that intervention is required when bamboo forests expand into Cunninghamia lanceolata forests.