降水和凋落物对木荷马尾松混交林土壤呼吸的影响

Soil respiration with precipitation and litter treatments in Schima superba and Pinus massoniana mixed forest

在未来气候变化中严重干旱事件将更加频发,这势必对陆地生态系统的碳收支施加重大影响。采用Li-8100土壤碳通量仪测定木荷Schima superba和马尾松Pinus massoniana混交林的土壤呼吸,分析延长干旱及土壤重新获得降水后,土壤呼吸及环境因子的变化特征,探讨土壤呼吸对环境因子变化的响应机制,有助于弄清土壤呼吸对未来极端气候事件的响应机制。设计了4种不同的处理方式:①零降水去除凋落物(NPNL);②零降水保留凋落物(NPCL);③自然降水去除凋落物(CPNL);④自然降水保留凋落物(CPCL)。结果表明:在零降水条件下,凋落物对土壤呼吸的贡献率仅为8.6%,显著低于同期自然降水(P<0.05)。自然降水条件下,去除凋落物处理(CPNL)和保留凋落物处理(CPCL)土壤呼吸温度敏感性Q10值分别为2.10和2.01;而采取零降水处理后,Q10值分别为2.59和2.72,表现为显著增加(P<0.05)。在1 a的零降水试验中,去除凋落物处理(NPNL)和保留凋落物处理(NPCL)土壤呼吸碳累积量比同期自然降水均表现为显著减少(P<0.05);移除透明室后,NPNL处理和NPCL处理土壤呼吸碳累积量比同期自然降水处理均表现为显著增加(P<0.05)。研究结果表明:延长干旱会减少土壤呼吸的释放,然而重新获得降水后,仍有部分碳未被释放出来,表明干旱或许有助于增加土壤碳库。

Extremely dry climatic events could occur more frequently with future climate changes which,in turn,could exert a strong influence on the terrestrial ecosystem and its carbon budget.Soil respiration of a Schima superba-Pinus massoniana mixed forest was measured in Fuzhou National Forest Park,Fujian,China using an infrared gas exchange analyzer.Characteristics of soil respiration and environmental factors after a prolonged drought followed by precipitation were analyzed and soil respiration response mechanism leading to possible changes in environmental factors also was discussed to help us to understand the response mechanism of soil respiration to future extremely climatic events.The research designed four treatments：（1） no-precipitation and no-litter（NPNL）;（2） no-precipitation and conserved litter（NPCL）;（3） natural precipitation and no-litter（CPNL）;（4） natural precipitation and conserved litter（CPCL）.Results showed that litter contributions to soil respiration with no-precipitation treatments were significantly lower than with natural precipitation treatments（P0.05）.In natural precipitation,temperature sensitivity Q10 values had ratios of 2.10 for soil respiration to no-litter（CPNL） and 2.01 for soil respiration to conserved litter（CPCL）;however,after no-precipitation,ratios were 2.59 for CPNL and 2.72 for CPCL,which depicted significant increase（P0.05）.With the no-precipitation treatment,soil respiration accumulation for no-litter（NPNL） and conserved litter（NPCL） was significantly less than with the natural precipitation treatment（P0.05） in no-precipitation experimental process.After removing closed transparent roofs,with the no-precipitation treatment of soil respiration accumulation for NPNL and NPCL was significantly more than with the natural precipitation treatment（P0.05）.Our results suggest that prolonged drought decrease releases of soil respiration,how ever,only partly released as increased respiration during regain precipitation,which show prolonged drought perhaps was help to increase soil carbon storage