复层异龄混交改造对杉木人工林土壤磷组分和转化的影响

Effectsof Multi-layer Mixed-age ModificationonSoil Phosphorus Componentsand Transformation in Cunninghamia lanceolata Plantation

关键词:  杉木人工林  土壤磷组分  微生物生物量  土壤酶活性  共现网络分析

Key words:  Cunninghamia lanceolata plantation  soil phosphorus components  microbial biomass  soil enzyme activity  co-occurrence network analysis

摘要:

为探究杉木(Cunninghamia lanceolata)人工林引入阔叶树种进行复层异龄混交改造对土壤磷(P)组分和转化的影响，本研究以未改造的杉木纯林(PP)和复层异龄混交改造后的杉木混交林(MP)作为研究对象，分析土壤理化性质和土壤P组分，并采用高通量测序和96孔荧光微孔板法分别测定土壤微生物群落组成和酶活性，阐明它们之间的关系。结果表明：(1)与PP相比，MP的极易利用性磷(RP)、易利用性磷(LP)、中等程度利用性磷(MAP)和难利用性磷(OP)分别显著提高9.43%、9.20%、11.64%和11.71%，磷素活化系数(PAC)显著提高27.13%。(2)MP中微生物生物量碳(MBC)、微生物生物量氮(MBN)和微生物生物量磷(MBP)较PP分别极显著增加13.52％、31.11％和55.78％，MP的微生物共现网络节点数、边数和平均加权度均高于PP。(3)和PP相比，MP中与碳(C)代谢相关的β-葡萄糖苷酶(BG)和纤维二糖水解酶(CB)土壤酶活性分别增加175.58％(P<0.01)和21.81％(P＜0.05)，与氮(N)代谢相关的N-乙酰-葡萄糖苷酶(NAG)土壤酶活性增加113.30％(P＜0.001)，与P代谢相关的酸性磷酸酶(ACP)土壤酶活性增加71.49%(P<0.01)，C、N和P代谢酶活性之间均呈显著的正相关关系。(4)土壤有机碳(SOC)、全氮(TN)和细根生物量(FR)是驱动土壤P组分发生变化的主要因子。综上，复层异龄混交改造可以通过影响植物性质和土壤的理化性质，提高土壤中各P组分含量和与土壤C、N和P相关的代谢酶活性，并在一定程度上有效促进杉木人工林土壤P的转化，提高其可利用性。该策略将为有效缓解亚热带杉木人工林土壤P限制提供新途径。

Abstract:

The purpose of this study was to investigate the effects of multi-layer mixed-age introduction of broad-leaved tree species into Cunninghamia lanceolata plantation on soil Phosphorus (P) components and transformation.The soil physicochemical properties and P components were measured in the unmodified Pure C.lanceolata Plantation (PP) and the Mixed C.lanceolata Plantation (MP) after multi-layer mixed-age modification.The soil microbial community composition and enzyme activity were determined by high-throughput sequencing and 96-well plate,respectively.Furthermore,the relationship of soil physicochemical properties and P components with soil microbial community and enzyme activity was clarified.The results showed that:(1)Compared with those in PP,the Resin Phosphorus (RP),Labile Phosphorus (LP),Medium Availability Phosphorus (MAP) and Oculude Phosphorus (OP) in MP were significantly increased by 9.43%,9.20%,11.64% and 11.71%,respectively,and the Phosphorus Activation Coefficient (PAC) was significantly increased by 27.13%.(2)The Microbial Biomass Carbon (MBC),Microbial Biomass Nitrogen (MBN) and Microbial Biomass Phosphorus (MBP) in MP significantly increased by 13.52%,31.11% and 55.78%,respectively,compared with those in PP.The number of nodes,the number of edges and the average weighting degree of the microbial co-occurrence network in MP were higher than those in PP.(3)Compared with PP,MP increased the activities of β-Glucosidase (BG) and Cellobiohydrolase (CB) related to Carbon (C) metabolism by 175.58%(P<0.01)and 21.81%(P<0.05),the activity of N-Acetyl-Glucosylase (NAG) related to Nitrogen (N) metabolism by 113.30%(P<0.001),and the activity of Acid Phosphatase (ACP) involved in P metabolism by 71.49%(P<0.01).There were significant positive correlations between the activities of enzymes associated with C,N and P metabolism.(4)Soil Organic Carbon (SOC),Total Nitrogen (TN) and Fine Root Biomass (FR) were the main factors driving the changes of soil P components.In conclusion,multi-layer mixed-age modification promotes soil P transformation and improves P availability in C.lanceolata plantation by altering the plant and soil physicochemical properties and increasing the content of P components and activities of enzymes involved in soil C,N and P metabolism.This approach may pave a new way for the alleviation of soil P limitation in subtropical C.lanceolata plantation.