【摘要】 土壤有机质是陆地生态系统最大的碳库,土壤有机质分解速率及其温度敏感性对生态系统碳循环及其碳汇功能具有重要影响。为揭示植被类型变化对森林土壤有机质分解的影响,以长白山针阔混交林的原生林和次生林为研究对象,分别将土壤在不同水分(30%、60%和90%土壤饱和含水量(SSM))和不同温度(5、10、15、20、25和30℃)下培养,在为期56 d的培养期内分9次测定土壤碳矿化速率。实验结果表明:植被类型、培养温度和水分对土壤碳矿化速率具有显著影响,且三者间存在显著的交互效应(P<0.001)。次生林土壤碳矿化累积量显著高于原生林(P<0.05),在90%SSM和温度30℃培养状况下分别为346.41μgC/g和241.01μgC/g。包含温度和水分的双因素模型可很好地拟合土壤碳矿化速率的变化,温度和水分可共同解释土壤碳矿化速率的82.7%—95.9%变异。次生林土壤碳矿化温度敏感性(Q10)显著高于原生林;水分对温度敏感性的影响较复杂,次生林在60%SSM最高,而原生林在90%SSM最高。总之,原生林遭砍伐后将会加速土壤有机质的分解,从而降低土壤有机质含量;另外,根据Q10值可以预测次生林土壤有机质的分解速率对全球变暖反映更明显。更多还原

【Abstract】 Soil organic matter(SOM) is the largest carbon pool in terrestrial ecosystems,with its temperature sensitivity playing an important role in the carbon(C) cycle and C sink at the ecosystem level. To elucidate how changes in vegetation types(primary forest versus secondary forest) influence SOM decomposition,we assessed a deciduous broad-leaved primary forest and secondary forest in the Changbai Mountains in the study,respectively; Soil samples from each forest type were incubated under different moisture(30%,60% and 90% saturated soil moisture(SSM)) and temperatures(5,10,15,20,25 and 30 ℃) condition. Then,SOM decomposition rates were measured at 9 times over 56 d incubation period. It was found that vegetation type,incubation temperature,and moisture had significant impacts on soil carbon mineralization rates,with a significant interaction among these parameters(P < 0.001). Higher accumulation of soil C mineralization occurred in the secondary forest compared to the primary forest,e. g.,346.41 μgC / g versus 241.01 μgC / g at 90% SSM and 30 ℃temperature,respectively. The two-factor models,including temperature and moisture,provide a good fit to soil C mineralization,with both temperature and moisture explaining 82.7% to 95.9% variation in soil C mineralization. Moreover,the temperature sensitivity(Q10) of soil C mineralization was significantly higher in the secondary forest than in the primary forest; however,moisture has a complex effect on Q10. For example,the highest Q10was obtained for 60% SSM in the secondary forest versus 90% SSM in the primary forest. Our findings indicate that transformation from primary forest to secondary forest would accelerate the decomposition rates of SOM,resulting in a larger loss of SOM. Moreover,secondary forests with higher Q10should are expected to be more sensitive to warmer scenarios in view of SOM decomposition. In conclusion,the complex impact of changing vegetation types change and soil moisture on the soil C cycle in forests requires focused research in future studies.更多还原