模拟林火高温对土壤有机碳及δ(13)^C的影响

Effects of Simulated High-temperature in Wildfires on Soil Organic Crbon and δ(13)^C

【目的】寒温带兴安落叶松林长期受到不同程度的林火干扰,但林火发生时不同林型土壤发生的实际情况、火后土壤有机碳(SOC)和同位素碳13C的变化规律仍不甚清楚,本文主要分析了寒温带典型林分火后SOC及其同位素碳13C变化特征,以期为火烧迹地恢复及土壤碳循环、碳周转过程的研究提供科学参考。【方法】在大兴安岭呼中林业局选取4块火烧迹地建立样地,测定并分析火烧迹地不同区域(中心区、边缘区和未过火林分)SOC含量、土壤δ(13)^C值,并利用不同温度(60℃,120℃,180℃,240℃)热处理未过火林分土壤,分析不同温度下SOC及δ(13)^C值的变化。【结果】结果表明:模拟火干扰下四种林型SOC含量均随着温度升高未发生显著变化。模拟温度不高于180℃时,土壤δ(13)^C值随温度升高逐渐降低,而模拟温度在180℃至240℃之间时土壤δ(13)^C值升高。而实际火干扰下,与未过火区相比,四组林型边缘区SOC含量无显著差异,而中心区SOC含量则显著降低(P<0.05),两组落叶松-偃松混交林边缘区土壤δ(13)^C值显著升高(P<0.05),而其余两组样地边缘区土壤δ(13)^C值则无显著变化,除以偃松为主的落叶松-偃松混交林外,其余三组样地中心区土壤δ(13)^C值均无显著变化。【结论】综上所述,较高的土壤温度可以显著改变土壤中SOC的储存量以及土壤δ(13)^C值(P<0.05),火后SOC含量及其碳同位素13C的变化则是由立地条件等多方因素影响。

【Objective】Larix gmelinii forests in the cold-temperate zone have been disturbed by different degrees of forest fires for a long time.However,changes in soil physicochemical properties in different forest types after the fires(e.g.soil organic carbon(SOC)and stable carbon isotope 13C(δ(13)^C))are still unclear.This paper mainly analyzes the variation characteristics of SOC and its isotope carbon 13C after fire in typical forest stands in cold temperate zone,in order to provide scientific reference for the recovery of burned areas and the research on soil carbon cycle and carbon turnover process.【Method】In this study,SOC and δ(13)^C in different burning areas(interior area,edge area,and unburned area)were quantified and analyzed in four burned sites of the Huzhong forestry bureau of the Greater Khingan Mountains.In addition,the soils in nearby unburned sites were heated at different temperatures(60℃,120℃,180℃,240℃)to analyze the changes of SOC and δ(13)^C under different temperatures.【Result】The results show that the SOC contents of the four forest types did not change significantly,and soil δ(13)^C ratios decreased with the increase of temperature when the simulated temperature was<180℃.But the soil δ(13)^C ratios increased when the simulated temperature was between 180℃and 240℃.However,under actual wildfires,compared with the unburned sites,there was no significant difference in SOC content at the edge area,but the SOC content in the interior area decreased significantly(P<0.05).The soil δ(13)^C ratios at the edge area of two Pinus pumila-Larix gmelinii mixed forests increased significantly(P<0.05),but there were no significant changes in soil δ(13)^C ratios at the edge area of the other two forests.There were also no significant changes in soil δ(13)^C ratios at the interior area in three plots,except for the Pinus pumilaLarix gmelinii mixed forest dominated by Pinus pumila.【Conclusion】In conclusion,relatively high soil temperature can significantly change SOC storage and soilδ(13)^C ratios(P<0.05).Under actual fire disturbance,the variation of SOC content and carbon isotope 13C after fires are influenced by many factors such as site conditions,This study will provide scientific reference for the research about soil carbon cycle and development of post-fire restoration strategies.