油茶低产林转化下土壤质量关键因子的识别与筛选

Identification and screening for key factors of soil quality under the conversion of low-yield Camellia oleifera forest

【目的】油茶作为中国南方脱贫的“摇钱树”,其增产增量对当地经济有重要作用。近年来,由于我国粮油储备需求的激增,对低产低效油茶老林的改造迫在眉睫,但改造过程对土壤质量的影响尚不清楚。皆伐后重新种植的林地,改变了凋落物和根际沉积物的组成并对土壤性质产生了的影响。通过进行转化前后土壤的对比,厘清调控林分土壤养分的关键因子,对低产油茶林改造具有重要的指导意义。【方法】对油茶老林,以及老林皆伐后新生油茶幼林、马尾松林、杉木林4种不同林分的土壤比对分析,测定了土壤化学性质、酶活性以及真菌丛枝菌群落多样性等13项指标,通过主成分分析和判别分析筛选修订最小数据集,构建该地区土壤质量评价指标体系,对土壤质量进行综合评价。【结果】土壤养分中pH值、全碳、全钾、镁、铁、锰、硝态氮在转化前后出现了显著差异。重新种植的马尾松林在酸性磷酸酶(Acid phosphatase,AP)、乙酰氨基葡萄糖苷酶(N-acetylglucosaminidase,NAG)、β-葡糖苷酶的活性(β-glucosidase,BG)中的活性均高于其他3种林分。通过PCA和MDS分析法筛选出该地区油茶土壤肥力评价指标最小数据集为硝态氮、全钾、速效钾、NAG、全氮、pH值、有机碳和全磷以及真菌多样性(Shannon),并证明通过林分转化能提高土壤质量。【结论】酸性土壤环境有助于油茶的生长,除了氮、磷、钾、镁之外针对油茶林还应关注铁、锰等微量矿物质含量。油茶作为菌根依赖性木本油料科植物,施肥时可考虑菌肥的使用,本研究可为今后该地区的土壤管理和精准施肥提供指导。

【Objective】Camellia oleifera,as a“money spinner”for poverty alleviation in southern China,has an important effect on local economy.In recent years,due to the surging demand for grain and oil reserves in China,it is urgent to reform the low-yield and low-efficiency old forest.However,the influence of the transformation process on soil quality and fungal community is still unclear.On the forest land replanted after clear cutting,the composition of litter and rhizosphere sediment has been changed,showing an impact on soil properties.By comparing the soil before and after the transformation,the key factors regulating the soil nutrients in the stand were clarified,which had important guiding significance for the transformation of the low-yield C.oleifera forest.【Method】This study collected soil samples from the old C.oleifera forest,young C.oleifera,Pinus massoniana forest and Cunninghamia lanceolata forest.We then determined 13 indexes including soil chemical properties,enzyme activity indexes and the community diversity of fungi.The minimum data set was selected and revised by the principal component analysis(PCA)and discriminant(MDA)analysis.The evaluation index system of soil quality in this area was established,and comprehensively evaluated.【Results】There were significant differences in pH,soil organic carbon(SOC),total potassium(K),magnesium(Mg),iron(Fe),manganese(Mn)and nitrate nitrogen(NO3)in the soil after transformation.The activities of acid phosphatase(AP),N-acetylglucosaminidase(NAG)andβ-glucosidase(BG)in the replanted P.massoniana forest were higher than others.Finally,it was demonstrated that the minimum data set of soil fertility evaluation indexes of C.oleifera in this area was significantly affected by nitrate,K,available K,NAG,total nitrogen(N),pH,SOC,total phosphorus(P),and fungal Shannon indexes.Moreover,SOI was improved by stand transformation.【Conclusion】Acidic soil environment is conducive to the growth of C.oleifera.Besides N,P,K and Mg,the trace mineral contents of Fe and Mn should be paid attention to in C.oleifera forests.Besides,as C.oleifera is a mycorrhizal-dependent woody oil plant,the use of fungal fertilizer can be considered when applying bacterial fertilizers.This study provides guidance for future soil management and precise fertilization in this area.