间伐强度对天然红松阔叶林土壤胞外酶活性及其化学计量比的影响

Effects of thinning intensity on soil extracellular enzyme activity and stoichiometric ratio in natural Pinus koraiensis broadleaf forest

【目的】研究不同间伐强度下红松阔叶林土壤胞外酶活性和化学计量比的变化,探讨间伐强度对土壤养分循环的影响,有利于红松阔叶林的可持续经营和生态功能的稳定。【方法】以吉林省长白山林区内的天然红松阔叶林为研究对象,选择4个间伐强度(CK,0%;LT,14%;MT,27%;HT,41%),测定并分析土壤养分、土壤胞外酶活性及其化学计量比,通过胞外酶矢量分析、相关性分析和冗余分析(RDA)揭示间伐强度对红松阔叶林土壤胞外酶活性及养分限制的影响。【结果】间伐显著降低了磷(P)获取酶活性(ACP),显著提高了碳(C)、氮(N)获取酶活性(CBH、BG、NAG、LAP),且随着间伐强度的增加,C、N获取酶均呈现出先升高后降低的趋势,在中度间伐达到最大。土壤EC∶P(0.99)和矢量长度(0.92)在重度间伐处较高,EC∶N(1.15)和矢量角度(57.21°)在未间伐处较高,表明土壤微生物在重度间伐和未间伐下分别具有较强的碳和磷限制。土壤铵态氮与C获取酶(CBH、BG)活性、EC∶N、EC∶P、矢量长度呈显著正相关关系(P<0.001),与P获取酶(ACP)活性显著负相关(P<0.01)。土壤全氮、铵态氮、硝态氮、有效磷、有机质是调控土壤胞外酶活性随间伐强度变化的重要因子。【结论】适宜的间伐强度可以提高土壤胞外酶活性,改善土壤微生物养分限制,促进土壤生物化学循环过程,研究结果可以为深入探讨间伐对天然次生林的养分循环和资源限制等研究提供理论支撑,为红松阔叶林的经营管理提供科学依据。

【Objective】Studying the changes in soil extracellular enzyme activity and stoichiometry under different thinning intensities in Pinus koraiensis broadleaf forests helps explore the impact of thinning intensity on soil nutrient cycling.This research contributes to the sustainable management and ecological stability of P.koraiensis broadleaf forests.【Method】This study focused on the natural P.koraiensis broadleaf forests in Changbai Mountain forest area of Jilin province,China,subjected to four thinning intensities(CK,0%;LT,14%;MT,27%;HT,41%).Soil nutrient content,soil extracellular enzyme activity,and their stoichiometry were measured and analyzed.Extracellular enzyme vector analysis,correlation analysis,and redundancy analysis(RDA)were used to reveal the impact of thinning intensity on soil extracellular enzyme activity and nutrient limitation in Korean pine broad-leaved forests.【Result】Thinning significantly reduced phosphorus(P)acquisition enzyme activity(ACP)while significantly increasing carbon(C)and nitrogen(N)acquisition enzyme activities(CBH,BG,NAG,LAP).Moreover,with increasing thinning intensity,both C and N acquisition enzymes showed an initial increase followed by a decrease,peaking at moderate thinning levels.Soil EC:P(0.99)and vector length(0.92)were higher under heavy thinning,while EC:N(1.15)and vector angle(57.21°)were higher in the unthinned forest,indicating stronger carbon and phosphorus limitations by soil microbes under heavy thinning and no thinning,respectively.Correlation analysis revealed significant positive relationships(P<0.001)between soil ammonium nitrogen and C acquisition enzyme activities(CBH,BG),EC:N,EC:P,and vector length,and a significant negative relationship(P<0.01)with P acquisition enzyme activity(ACP).RDA analysis indicated that soil total nitrogen,ammonium nitrogen,nitrate nitrogen,available phosphorus,and organic matter were important factors regulating soil extracellular enzyme activity with changing thinning intensity.【Conclusion】Appropriate thinning intensity can enhance soil extracellular enzyme activity,alleviate soil microbial nutrient limitations,and promote soil biogeochemical cycling.These findings provide theoretical support for further research on nutrient cycling and resource limitations in natural secondary forests under thinning and offer a scientific basis for the management of P.koraiensis broadleaf forests.