摘 要

本文采用抖落法收集根际土，用氯仿熏蒸-K₂SO₄提取法测定不同间伐强度下根际土壤微生物碳氮含量，并分析其与理化性质的关系，于南京市溧水林场间伐10年后的30年生的马尾松（Pinus massoniana Lamb. ）人工林为研究而对象，研究在4种间伐强度下（对照组CK 未间伐，弱度间伐LIT 25%，中度间伐MIT 45%，强度间伐 HIT 65%）根际土壤微生物碳氮含量的变化。旨在明晰根际土壤中碳氮含量对间伐的响应程度，探究不同间伐强度下根际碳氮含量差异的原因。该研究可为制定马尾松合理的间伐强度，进一步理解间伐对土壤碳氮循环的影响机理提供参考数据。

研究表明，在四种间伐强度下，土壤微生物氮、碳含量的根际效应值均大于1，表现为正根际效应；间伐改变了土壤微生物量碳氮，与CK组相比，LIT组与MIT组非根际土壤微生物显著提高，而HIT组降低，呈现为HITlt;CKlt;MITlt;LIT；四种间伐强度下，根际土壤微生物量碳都低于CK组，且各组之间存在显著差异，呈现为HITlt;LITlt;MITlt;CK。LIT组和MIT组的微生物量氮与CK组相比有显著提高，HIT组的非根际土壤微生物量氮略高于CK无显著差异，四种强度间伐下，非根际土壤微生物量氮呈现为CKlt;HITlt;MITlt;LIT；与CK组相比，HIT组的根际土壤微生物量氮略微下降，但不显著，呈现为HITlt;CKlt;MITlt;LIT。结果表明微生物量氮与土壤含水量，pH呈极显著相关性；微生物量碳与土壤全氮呈显著相关性。总体来说，轻度间伐与中度间伐能提高根际土壤微生物碳氮含量，可以作为马尾松间伐强度的参考指标。

关键词：间伐；马尾松人工林；土壤微生物量氮；土壤微生物量碳

Effects of thinning on microbial biomass carbon and nitrogen contents in rhizosphere soil of Pinus massoniana plantation

ABSTRACT

In this paper, we use the shaking method to collect rhizosphere soil , and the content of carbon and nitrogen in rhizwosphere soil was measured by -K₂SO₄ extraction with chloroform fumigation, and the relationship between the soil microbial biomass and its physicochemical properties was analyzed. The 30 year old plantation of Masson pine (Pinus massoniana Lamb.) was studied after 10 years of thinning in the Lishui forest farm,Nanjing. In 4 kind of intensities of thinning (control group CK without thinning, weak thinning LIT 25%, medium thinning MIT 45%, intensity thinning HIT 65%) the change of microbial carbon and nitrogen content in rhizosphere soil.The aim was to clarify the response degree of carbon and nitrogen content to thinning in rhizosphere soil, and to explore the reasons for the difference of carbon and nitrogen contents in Rhizosphere under different thinning intensities.This study can provide reference data for establishing reasonable thinning intensity of Pinus massoniana and further understanding the mechanism of thinning on soil carbon and nitrogen cycling.

The results showed that under the four kind of intensities of thinng, the rhizosphere effect values of soil microbial nitrogen and carbon content were all greater than 1, showing the positive rhizosphere effect.Soil microbial biomass carbon and nitrogen were changed by thinning. Compared with the CK group, the non rhizosphere soil microbes in the LIT group and the MIT group were significantly increased, while the HIT group was reduced to HITlt;CKlt;MITlt;LIT.Under the four thinning intensities, the microbial biomass carbon in rhizosphere soil was lower than that in CK group, and there was a significant difference between each group, showing HITlt;LITlt;MITlt;CK. The microbial biomass nitrogen in LIT and MIT groups was significantly higher than that in the CK group. The microbial biomass nitrogen in the non rhizosphere soil of the HIT group was slightly higher than that in the CK, and the microbial biomass nitrogen in the non rhizosphere soil was CKlt;HITlt;MITlt;LIT under the four intensity thinning. Compared with the CK group, the microbiological nitrogen in the rhizosphere soil of the HIT group decreased slightly, but was not significant. Now it's HITlt;CKlt;MITlt;LIT. The results showed that microbial biomass nitrogen had a significant correlation with soil water content and pH, and microbial biomass carbon had a significant correlation with soil total nitrogen. In general, weak thinning and moderate thinning can increase soil microbial biomass carbon and nitrogen content, and this experimental result can be used as a reference index for thinning intensity of Masson pine.

Key words：Thinning; Pinus massoniana plantation; soil microbial biomass nitrogen; soil microbial biomass carbon

目 录

1 选题背景及选题意义………………………………………………………...................………….........1

1.1选题背景………………………………………………………….........................................…….......1

1.2选题意义………………………………………………………………….....................................……2

2.国内外研究进展………………………………………………………………………………..................3

2.1 间伐的研究进展…………………………………………………………………….........................2

2.1.1间伐对土壤的理化性质的影响……………………………………………………….........……2

2.1.2间伐对土壤中微生物的影响…………………………………………………………….....……4

2.2 根际土壤微生物量的研究进展…………………………………………………………….......……4

3 材料与方法............………………………………………………………………………..............………6

3.1 研究区域概况……........………………………………………………………….......................……5

3.2样地设置…......…………………………………………………………………..........................……5