间伐对杉木人工林土壤微生物生物量碳氮的短期影响

【目的】探究大径材培育目标下间伐对杉木人工林土壤微生物生物量碳氮的短期影响,为缓解杉木人工林地力衰退问题和大径材定向培育提供指导。【方法】以16年生杉木人工林为对象,采用完全随机区组设计,设置3种间伐强度,分别为强度间伐(32%,编号HIT)、弱度间伐(23%,编号LIT)、对照组(0%,编号CK),研究不同间伐条件下杉木人工林的土壤微生物生物量碳(SMBC)、生物量氮(SMBN)含量的变化及其化学计量特征土壤微生物生物量碳、氮含量比,土壤微生物生物量碳、氮与土壤全碳(TC)、全氮(TN)含量比,即SMBC/SMBN、SMBC/TC、SMBN/TN]之间的差异。【结果】在不同间伐强度下,杉木人工林不同土层SMBC、SMBN含量及SMBN/TN的值从大到小依次为HIT、LIT、CK;SMBC/TC的值除在≥10~20 cm土层以强度间伐(HIT)最高之外,其他土层均以弱度间伐(LIT)最高;SMBC/SMBN的值除在≥20~40cm土层,以CK最高外,其他土层均以LIT处理最高;从土壤的垂直分布特征来看,杉木人工林SMBC、SMBN含量从大到小依次为0~10、≥10~20、≥20~40 cm,即呈现出SMBC、SMBN含量随土层加深而降低的趋势。【结论】强度间伐对SMBC、SMBN含量影响明显,可能有利于提高土壤肥力;加强对土壤地力的维护,从而改善杉木大径材的培养。

Short-term effects of thinning on soil microbial biomass carbon and nitrogen in a Cunninghamia lanceolata plantation

【Objective】The short-term effects of thinning on soil microbial biomass carbon (SMBC) and nitrogen (SMBN) in a Chinese fir (Cunninghamia lanceolata) plantation were investigated. The results of this study provide important information for alleviating the decline in soil fertility in Chinese fir plantations and for targeted cultivation of large diameter Chinese fir plantation.【Method】Soil microbial biomass C and N and stoichiometric characteristics specifically the mass of SMBC to SMBN, and the percentage of SMBC and SMBN relative to soil total carbon (TC), and total nitrogen (TN), respectively] at depths of 0-10, ≥10-20 and ≥20-40 cm were examined in a 16-year-old Chinese fir plantation. Three thinning intensities were implemented in a completely randomized block design: high-intensity thinning (HIT), light-intensity thinning (LIT) and non-thinning (CK).【Result】In relation to thinning intensity, the values for SMBC, SMBN and SMBN/TN in all soil layers were in the order: HIT > LIT > CK. The SMBC/TC value was highest under LIT in all soil layers except for ≥10-20 cm, which was highest under HIT. The ratio of SMBC to SMBN was highest under LIT in all soil layers except for ≥20-40 cm, which was highest in the CK. Regarding the vertical distribution in the soil profile, the amount of SMBC and SMBN decreased with soil depth.【Conclusion】These findings suggest that HIT has a significant effect on SMBC and SMBN which may be beneficial in maintaining and improving soil fertility, and in the cultivation of large diameter Chinese fir timber.