间伐对马尾松人工林土壤活性有机碳的影响

Effects of thinning intensity on soil active organic carbon in Pinus massoniana plantation

以南京市溧水区林场间伐9年后的29年生马尾松人工林为研究对象,探讨了不同间伐强度(对照:0%;弱度间伐:25%;中度间伐:45%;强度间伐:65%)对土壤3种活性有机碳含量及其在总有机碳中比例的影响。结果表明:与对照样地相比,中度间伐显著提高了土壤总有机碳含量,强度间伐显著降低了土壤总有机碳含量;土壤颗粒有机碳与易氧化有机碳含量对间伐的响应与总有机碳规律一致,土壤轻组有机碳含量在3种间伐强度下显著降低,表现为强度间伐<弱度间伐<中度间伐<对照;土壤颗粒有机碳、轻组有机碳及易氧化有机碳在总有机碳中的比例分别为30.83%~64.59%、10.40%~26.92%、3.61%~4.62%。3种间伐强度显著降低了土壤轻组有机碳在总有机碳中的比例,对土壤易氧化有机碳在总有机碳中的比例无显著影响,中度间伐显著降低了土壤颗粒有机碳在总有机碳中的比例。中度间伐利于土壤总有机碳的积累,且土壤有机碳稳定性高。

We studied the effects of thinning on soil active organic carbon content and their proportion in total organic carbon in a 29-year-old Pinus massoniana plantation after nine years of treatment. Four thinning intensities included： light（ 25%,LIT）,moderate（ 45%,MIT）,high（ 65%,HIT）,and a control（ 0%,CK）. The results showed that compared with the CK,MIT significantly increased soil total organic carbon（ TOC） content,while HIT significantly decreased TOC content. The responses of soil particulate organic carbon（ POC） and readily oxidized carbon（ ROC） to thinning were consistent with the TOC. The light fraction organic carbon（ LFOC） content of soil was significantly decreased under the three kinds of thinning intensity in the order of HIT〈 LIT〈 MIT〈 CK. The distribution proportion of POC,LFOC and ROC in the TOC ranged from 30.83% to 64.59%,10.40% to 26.92% and 3.61% to 4.62%,respectively. Thinning significantly decreased the distribution proportion of LFOC in the TOC. However,thinning had no significant effect on the distribution proportion of ROC in the TOC. MIT significantly decreased the distribution proportion of POC in the TOC. Compared to the CK,MIT was advantageous in the accumulation of TOC with enhanced stability of soil organic carbon.