不同经营模式日本落叶松人工林土壤理化性质及综合评价

Soil Physical-chemical Properties and Comprehensive Evaluation of Larix kaempferi Plantations under Different Management Models

以湖北省恩施州建始县国有长岭岗林场32年生5种经营模式日本落叶松(Larix kaempferi)人工林——5落∶5鹅的日本落叶松-鹅掌楸(Liriodendron chinense)混交林、7落∶3鹅的日本落叶松-鹅掌楸混交林、5落∶5檫的日本落叶松-檫木(Sassafras tzumu)混交林、7落∶3檫的日本落叶松-檫木混交林、日本落叶松纯林为研究对象,每种模式林分设置3个20 m×20 m样方,在各样方中沿对角线分上、中、下部选择3个样点,应用环刀取样法采集0~20 cm深土层原状土样品,测定土壤理化性质;以15个土壤理化性质(7个物理性质、8个化学性质)为平价指标,应用主成分分析法、多维空间坐标综合评定值累加法、模糊隶属函数法,分析不同经营模式对土壤理化性质的影响。结果表明:(1)除土壤密度、非毛管空隙度外,混交经营模式土壤理化性质各指标均高于纯林经营模式;不同经营模式对土壤理化性质的影响不同,整体表现出随混交树种不同和混交比例的增大呈差异性显著增大趋势。(2)不同经营模式土壤理化性质之间存在一定的相关性,土壤密度与各理化性质指标均呈负相关,pH与土壤物理性质各指标均呈显著相关,土壤物理性质与有机质、土壤养分相关性密切。(3)3种评价方法结果较一致,混交经营模式土壤理化性质优于纯林经营模式的,以5落∶5檫的日本落叶松-檫木混交经营模式为最优。可见,合理的混交经营模式更有利于改善土壤生态环境,混交树种和混交比例是影响土壤理化性质的重要因素;植被对土壤理化性质的影响是一个长期的过程,仍需加强长期监测和深入研究。

Taking five management models of Larix kaempferi plantation in State-owned Changlinggang Forest Farm of Jianshi County(Mixed forest of Larix kaempferi-Sassafras tzumu,Larix kaempferi-Liriodendron chinense with two mixed ratios of 5∶5 and 7∶3,pure Larix kaempferi forest)as the research object,the characteristics and correlation of physical and chemical properties at soil depths of 0-20 cm were studied,and the principal component analysis,multidimensional coordinate-synthetic-evaluation method and subordinate-function-value method were used to comprehensively evaluate the soil physical and chemical properties,so as to explore the effects of different management models on soil physical and chemical properties,and provide scientific basis for soil nutrient management and sustainable management of Larix kaempferi plantation.The results showed that:(1)Except for soil bulk density and Non-capillary porosity,the soil physical and chemical properties of mixed management models were higher than that of pure forest management model;the effects of different management models on soil physical and chemical properties were different,the overall performance showed a significant increase trend with different mixed tree species and the increase of the mixed ratio.(2)There was a certain correlation between soil physical and chemical properties under different management models.Soil bulk density was negatively correlated with all physical and chemical properties,pH value was significantly correlated with all physical properties,and soil physical properties were closely related with organic matter and soil nutrients.(3)The results of three evaluation methods were consistent,the soil physical and chemical properties of mixed management models were better than that of pure forest management model,and the mixed management model of Larix kaempferi-Sassafras tzumu with a mixed ratio of 5∶5 was the best.It can be seen that the reasonable mixed management mode is more conducive to improving the soil ecological environment,the mixed tree species and proportion are the important factors affecting the soil physical and chemical properties;the effect of vegetation on soil physical and chemical properties is a long-term process,which still needs to be further monitored and studied.