不同密度调控强度对华北落叶松人工林土壤质量的影响

Effects of different density regulation intensities on soil quality in Larix principis-rupprechtii plantation

【目的】探究不同密度调控强度华北落叶松人工林土壤质量的变化规律,为合理利用林地资源及人工林的可持续经营提供理论依据。【方法】以山西太岳山好地方林场华北落叶松人工林为研究对象,基于土壤密度、含水率、养分含量、酶活性等18项土壤指标,并结合主成分分析和相关系数法建立土壤质量评价最小数据集,采用加权求和指数法对不同密度调控强度的(对照,2096株/hm^(2),CK;低强度处理,1850株/hm^(2),LT;中强度处理,1402株/hm^(2),MT;高强度处理,1106株/hm^(2),HT)华北落叶松人工林土壤质量进行综合评价。【结果】与对照相比,LT、MT和HT样地土壤含水率呈增加趋势;从密度调控对土壤养分影响而言,MT处理下C、N和P等养分含量均较高。此外,土壤生物学性状也对不同调控强度存在显著响应,其中土壤微生物生物量碳、氮含量在MT显著高于CK;脲酶和多酚氧化酶活性在MT最高,过氧化物酶活性在LT最高,蔗糖酶活性在CK最高,而纤维素酶活性随密度调控强度增加整体呈下降趋势。结合主成分分析和相关性分析结果可知,有机质、含水率、微生物生物量氮、多酚氧化酶、过氧化物酶构成了土壤质量评价的最小数据集。不同密度调控强度华北落叶松人工林土壤质量指数大小为MT(0.598)>HT(0.510)>LT(0.432)>CK(0.339)。【结论】密度调控可有效改善华北落叶松人工林土壤质量状况,中等林分密度下土壤质量指数最高。建议对华北落叶松人工林进行适度密度调控处理,以提高人工林地土壤质量。

[Objective]This paper aims to explore the variation law of soil quality of Larix principisrupprechtii plantation under different density regulation intensities,which provides a theoretical basis for rational utilization of forest land resources and sustainable management of plantation.[Method]In this study,we analyzed 18 soil indexes including soil density,moisture content,nutrient content and enzyme activity in L.principis-rupprechtii plantation,under four different density regulation intensities(control,2096 tree/ha,CK;low intensity treatment,1850 tree/ha,LT;moderate intensity treatment,1402 tree/ha,MT;high intensity treatment,1106 tree/ha,HT)in Taiyue Mountain,Shanxi Province of northern China.And the minimum data set(MDS)of soil quality evaluation was established by combining principal component analysis(PCA)and correlation analysis.Finally the soil quality of L.principis-rupprechtii plantation was synthesized by the weighted additive index.[Result]Compared with CK,the soil moisture of LT,MT and HT increased.In terms of the effects of density regulation on soil nutrients,the contents of C,N and P in MT were higher.In addition,soil biological properties also showed significant response to different regulation intensities,among which,soil microbial biomass carbon and nitrogen contents in MT were significantly higher than those in CK;urease and polyphenol oxidase activities were the highest in MT,peroxidase activity was the highest in LT,and sucrase activity was the highest in CK,while cellulase activities showed a downward trend with the increase of density regulation intensity.The results of PCA and correlation analysis showed that the MDS for soil quality evaluation included organic matter,moisture content,microbial biomass nitrogen,polyphenol oxidase and peroxidase.The order of soil quality of different density regulation intensity plantation was as following:MT(0.598),HT(0.510),LT(0.432),CK(0.339).[Conclusion]Density regulation can effectively improve the soil quality of L.principis-rupprechtii plantation,and the soil quality index of medium stand density is the highest.Therefore,we recommend moderate density regulation to L.principis-rupprechtii plantation to promote soil quality.