广西不同林龄马尾松人工林土壤碳储量动态变化

Dynamic Changes of Soil Carbon Storage of Pinus massoniana Plantations at Different Stand Ages in Guangxi

关键词:  土壤有机碳含量  土壤碳储量  影响因子  林龄  马尾松人工林

Key words:  soil organic carbon content  soil carbon storage  influencing factors  stand ages  Pinus massoniana plantations

摘要:

为了解不同林龄马尾松Pinus massoniana人工林土壤碳储量的动态变化，选取广西横县镇龙林场不同林龄（幼龄林、中龄林、成熟林、过熟林）的马尾松人工林为研究对象，对林地土壤有机碳含量及土壤碳储量的变化特征进行研究，并探讨其影响因素。研究表明，随着林龄递增，各土层土壤有机碳含量及土壤碳储量总体表现为增加趋势，且不同林龄的同一土层之间均差异显著。不同林龄0—60 cm土层土壤有机碳含量表现为过熟林（16.82±0.23）g/kg > 成熟林（13.47±0.14）g/kg > 中龄林（10.91±0.38）g/kg > 幼龄林（10.74±0.14）g/kg，且差异显著（P<0.05）。不同林龄0—60 cm土层土壤碳储量表现为过熟林（104.92±18.08）t/hm²>成熟林（100.52±1.18）t/hm² > 中龄林（80.25±5.34）t/hm² > 幼龄林（80.23±4.54）t/hm²，且差异显著（P<0.05）。各林龄土壤有机碳含量、土壤碳储量主要集中在0—20 cm土层，并随土层深度的增加而递减，表现为土壤碳表聚现象，表层（0—20 cm）土壤碳储量所占比例均明显高于其他土层，表明不同林龄主要影响马尾松人工林土壤表层的碳含量；不同林龄土壤有机碳含量、土壤碳储量与乔木、灌木层Shannon-Wiener指数、物种丰富度、凋落物层现存量、总孔隙度、土壤含水量、土壤pH值均无显著相关关系（P>0.05），与根系生物量呈极显著正相关关系（P<0.01），与土壤容重呈极显著负相关关系（P<0.01）；群落总生物量、地上部分生物量均与表层（0-20 cm）土壤有机碳含量和土壤碳储量呈极显著正相关关系（P<0.01），与20-40，40-60 cm土层土壤有机碳含量呈显著正相关关系（P<0.05），而与后两个土层的土壤碳储量均无显著相关。该结果为研究土壤碳储量动态变化提供科学依据，有利于实现尾松人工林多目标可持续经营。

Abstract:

The objective of this study was to understand the dynamic changes of soil carbon storage in Pinus massoniana plantations of different stand ages. The P.massoniana plantations of different ages (young stand,middle-aged stand,mature stand,and overripe stand) of Zhenlong Forest Farm of Hengxian in Guangxi were selected as the research object to study the change characteristics of forest soil organic carbon content and soil carbon storage,and discuss its influencing factors. The results showed that with the growth of stand age,the soil organic carbon content and soil carbon storage of each soil layer showed an overall increasing trend,and there were significant differences in different forest ages of the same soil layer. The soil organic carbon content in the 0-60 cm soil layer at different stand ages was as follows:Overripe stand (16.82±0.23) g/kg > mature stand (13.47±0.14) g/kg > middle-aged stand (10.91±0.38) g/kg > young stand (10.74±0.14) g/kg,and the difference was significant (P<0.05). The soil carbon storage in the 0-60 cm soil layer at different stand ages was as follows:Overripe stand (104.92±18.08) t/hm² > mature stand (100.52±1.18) t/hm² > middle-aged stand (80.25±5.34) t/hm² > young stand (80.23±4.54) t/hm²,and the difference was significant (P<0.05).The soil organic carbon content and soil carbon storage of each stand age were mainly concentrated in the 0-20 cm soil layer,and decreased with the increase of soil layer depth,which was manifested as the phenomenon of soil carbon accumulation. The proportion of soil carbon storage in surface layer (0-20 cm) was significantly higher than that of other soil layers,indicating that the P.massoniana plantations of different ages mainly affected the carbon content of the soil surface layer. There was no significant correlation between the soil organic carbon content,soil carbon storage of different stand ages and the Shannon-Wiener index,species richness,litter layer existing stock,total porosity,soil water content,soil pH value of trees and shrubs (P>0.05),and it had a extremely significant positive correlation with root biomass (P<0.01),and a extremely significant negative correlation with soil bulk density (P<0.01).The total biomass and above-ground biomass of the community were significantly positively correlated (P<0.01) with the soil organic carbon content and soil carbon storage in the surface layer (0-20 cm),and were significantly positively correlated with the soil organic carbon content in the 20-40 and 40-60 cm layers (P<0.05),but there was no significant correlation with the soil carbon storage in the latter two layer. The results provided a scientific basis for studying the dynamic changes of soil carbon storage,which was ultimately conducive to the realization of multi-objective sustainable management of P.massoniana plantations.