中度火干扰对兴安落叶松林土壤呼吸的影响

摘要

This study investigated the increasing seasonal soil respiration (Rs) in the Dahurian Larch (Larix gmelinii) forests after fire disturbance in the Tahe area,and identified the main environmental factors influencing soil respiration changes after fires.Plots that had been under fire disturbance over four years in the Tahe forestry bureau were selected for this investigation,and the nearby unbumt area was selected for the control plots.The Rs was measured by using an Li8100,and the trench method was used to measure the soil heterotrophic respiration (Rh).The mean Rs of post-fire plots and unburnt control plots was (3.67±1.03)μmol CO2 m-2 s-1 and (4.21±1.25)μmol CO2 m-2 s-1,respectively.The Rs in the post-fire plots was significantly lower than that in the unburnt control plots (P ＜ 0.05).We quantified the Rs component changes after fire disturbance.The decrease in Rs was mainly due to a significantly decreased autotrophic respiration (Ra) rate (P ＜ 0.05).Soil temperature was the dominant environmental factor influencing soil respiration variability in this area.Compared with the unburnt control plots,the Rs in the post-fire plots had a much stronger correlation with soil temperature.The temperature sensitivity index (Q10) of Rs in the post-fire plots and unburnt control plots was 5.85± 1.06 and 4.25±1.19,respectively.The Q10 value significantly increased after fire disturbance (P ＜ 0.05).In view of the global climate change,the results of this study demonstrate that the Dahurian Larch (L.gmelinii) forest ecosystem in the Tahe area of China is sensitive to temperature change.Our findings provide scientific basis for research on carbon cycling after fire disturbance in the Tahe area of China.%通过测定中度火干扰后塔河地区兴安落叶松(Larix gmelinii)林生长季土壤呼吸(Rs),并进一步探究火干扰后影响土壤呼吸变化的主要环境因子.选择在塔河林业局火烧4年后兴安落叶松林中度火烧迹地设置样地,选择临近未过火区域设置对照样地.土壤呼吸通量用LI-8100进行测量,土壤异养呼吸(Rh)采用壕沟法进行测量.火烧迹地与未火烧对照样地生长季土壤呼吸速率平均值分别为(3.67±1.03) μmol CO2 m-2 s-1,(4.21±1.25) μmol CO2m-2 s-1.火烧迹地土壤呼吸速率显著降低(P＜0.05).生长季土壤呼吸组分的动态变化表明,土壤呼吸速率的降低是因为土壤自养呼吸(Ra)显著降低导致的(P＜0.05).温度是控制这一地区生长季土壤呼吸变化的主要环境因子.与对照样地相比,火烧迹地土壤呼吸的变化与土壤温度具有更强的相关性.塔河地区兴安落叶松林火烧迹地和未火烧对照样地Q10分别为5.85±1.06,4.25± 1.19,火干扰后Q10显著增加(P＜0.05).研究结果表明:在全球气候变化的背景下火干扰后中国塔河地区兴安落叶松林生态系统对温度的变化更为敏感.本研究结果将为研究中国塔河地区火干扰后碳循环变化提供数据支持.