不同间伐强度对华北落叶松人工林土壤养分-微生物生物量-胞外酶化学计量的影响

Effects of different thinning intensities on the C∶N∶P stoichiometry of soil nutrients,microbial biomass,and extracellular enzymes in Larix principis-rupprechtii plantations

【目的】探究间伐强度对土壤养分-微生物生物量-胞外酶化学计量特征的影响。【方法】以河北省塞罕坝机械林场华北落叶松人工林为研究对象,设置不同间伐强度(对照、轻度间伐、中度间伐和重度间伐)标准地,采集0~10、10~20和20~30 cm土壤样品,测定土壤养分含量、微生物生物量含量和胞外酶活性,分析土壤养分-微生物生物量-胞外酶化学计量比。【结果】1)随间伐强度增大,土壤碳(C)、氮(N)、磷(P)含量先增后降,在中度间伐中观测到最大值;间伐降低了土壤C∶N、C∶P和N∶P。2)间伐提高了土壤微生物生物量碳、氮和磷(MBC,MBN和MBP)含量,尤其是中度间伐;间伐提高了土壤MBC∶MBN而降低了MBN∶MBP,土壤MBC∶MBP在不同间伐强度间无显著差异(P>0.05)。3)土壤β-1,4-葡萄糖苷酶(BG)活性在不同间伐强度间未表现出显著差异(P>0.05),土壤β-1,4-N-乙酰氨基葡萄糖苷酶+亮氨酸氨肽酶(NAG+LAP)活性、酸性磷酸酶(AP)活性和(NAG+LAP)∶AP在中度间伐和重度间伐中显著高于对照和轻度间伐(P<0.05),中度间伐和重度间伐的BG∶(NAG+LAP)显著低于对照和轻度间伐(P<0.05),中度间伐的土壤BG∶AP显著低于对照(P<0.05)。【结论】间伐能够促进养分循环,尤其是中度间伐。研究结果可为不同间伐强度人工林中养分循环、资源限制和生态过程研究提供理论支撑,为该区域华北落叶松人工林的合理经营提供理论依据。

【Objective】This study was aimed to study the effects of thinning intensity on the C∶N∶P stoichiometry of soil nutrients,microbial biomass,and extracellular enzymes.【Method】Taking Larix principis-rupprechtii plantations in the Saihanba Mechanical Forest Farm in Hebei Province as the research object,this study set standard plots with different thinning intensities(control,light thinning,moderate thinning,and heavy thinning).Samples from the 0-10,10-20,and 20-30 cm soil layers were collected.The soil nutrient contents,microbial biomass,and extracellular enzyme activities were determined.The stoichiometric ratios of soil nutrients,microbial biomass,and extracellular enzymes were analyzed.【Result】1)With the increase of thinning intensity,the contents of soil carbon(C),nitrogen(N),and phosphorus(P)increased firstly and then decreased,and the maximum values were observed in the moderate thinning group.Thinning reduced soil C∶N,C∶P and N∶P ratios.2)Thinning,especially moderate thinning,increased the contents of soil microbial biomass including carbon,nitrogen,and phosphorus(MBC,MBN,and MBP).Thinning increased soil MBC∶MBN ratios but reduced MBN∶MBP ratios.There were no significant differences in the soil MBC∶MBP ratios among the treatments with different thinning intensities(P>0.05).3)The activity of soilβ-1,4-glucosidase(BG)showed no significant differences among different thinning treatments(P>0.05).Soilβ-1,4-N-acetylglucosaminidase+leucine aminopeptidase(NAG+LAP)activity,acid phosphatase(AP)activity,and(NAG+LAP)∶AP ratios in the moderate thinning and heavy thinning groups were significantly higher than those of the control and light thinning group(P<0.05).The soil BG∶(NAG+LAP)ratios in the moderate thinning and heavy thinning groups were significantly lower than that of the control and light thinning group(P<0.05).The soil BG∶AP ratios in the moderate thinning group was significantly lower in comparison with control(P<0.05).【Conclusion】Thinning can promote nutrient cycling,especially moderate thinning.The research results can provide theoretical support for the studies of nutrient cycling,resource limitation,and ecological processes in plantations with different thinning intensities,and offer a theoretical basis for the rational management of Larix principis-rupprechtii plantations.