长白山两种森林类型土壤有机碳库及其剖面分布特征

Soil Organic Carbon Pools and Profile Distribution under Broad-Leaved Korean Pine Forest and Betula platyphylla Secondary Forest in Changbai Mountain

【目的】全球气候变化的背景下,森林土壤在陆地生态系统碳平衡和碳固存中起着越来越重要的作用,而次生演替是森林土壤有机碳库变化的重要驱动因素。【方法】本文以长白山原始阔叶红松林和杨桦次生林为例,通过严格的样地对比途径,研究了两种林型土壤中有机碳库大小及其剖面分布差异,旨在探讨次生演替对温带森林土壤碳源汇效应的影响及机制。【结果】杨桦次生林比原始阔叶红松林在表层和亚表层(0~20 cm)土壤积累了更多的有机碳,而在深层土壤中有机碳含量和密度无显著差异,表明林型或次生演替对土壤有机碳库的影响仅限于表层和亚表层。两种林型5~10 cm与0~5 cm土层、10~20 cm与5~10 cm土层有机碳含量均表现为显著正相关,但杨桦次生林上部土层对下部土层的决定系数(R2)明显高于阔叶红松林,即杨桦次生林上部土层有机碳含量对下部土层的影响比原始阔叶红松林更明显。【结论】土壤动物活动和土壤环境改变所致根系分布变化可能是次生演替引起土壤有机碳库变化的重要原因;次生演替过程中土壤有机碳库变化的主要驱动机制尚有待研究。

【Objective】Under the background of global climate change,forest soil plays an important role in the carbon balance and carbon sequestration in terrestrial ecosystem.Broad-leaved Korean pine mixed forest is the most important climax in northeast China.Due to the disturbance of human activities decades ago,secondary forests gradually replaced the Korean pine forest.And the retrogressive succession progress is recognized as an important driving force for changes in soil organic carbon(SOC)pools.【Method】In this study,the SOC pool size and its profile distribution were investigated through a strict contrastive sampling approach,in the case of typical original Broad-leaved Korean Pine Forest(KP)and Betula platyphylla Secondary Forest(BP)in Changbai Mountain.【Result】This paper aims to probe into the carbon source/sink effect and its mechanisms of temperate forest soils as driven by secondary succession.It resulted that the BP forest accumulated more organic carbon in the surface(0-5 cm,5-10 cm)and subsurface(10-20 cm)soil than KP forest.There was no significant difference in SOC content and SOC density in the deeper(>20 cm)soil layers of the two forest types,thus the influence of forest type or secondary succession on SOC pool size was just limited to the surface and subsurface layer(0-20 cm).While overall,the SOC content of the underlying 5-10 cm or 10-20 cm soil layer was positively and significantly correlated with that of the overlaying 0-5 cm or 5-10 cm soil layer,respectively,the linear coefficient of determination(R2)between underlying and overlaying soil layers in BP forest was much higher than that of the KP forest,which indicates a more significant'pedoturba tion'effect in the BP forest.【Conclusion】The secondary-succession-resulted changes in SOC pool size and allocation was partly attributed to improved soil animal activity and fine root distribution,while the predominant driving mechanism was still remained to be further studied.