大兴安岭北部不同类型兴安落叶松林土壤呼吸及其组分特征

Soil respiration and its component characteristics under different types of Larix gmelinii forests in the north of Daxing'an Mountains of northeastern China

【目的】研究大兴安岭地区兴安落叶松林土壤呼吸及其组分的特征以及与土壤温度、湿度两个影响因子之间的关系,为进一步阐明我国寒温带地区碳释放及其对地区气候的影响提供科学依据。【方法】使用LI-6400对大兴安岭北部5种主要类型兴安落叶松林(落叶松纯林、兴安杜鹃-落叶松林、杜香-落叶松林、白桦-落叶松林和樟子松-落叶松林)的土壤呼吸、呼吸组分及其影响因子进行测定分析。【结果】5种类型兴安落叶松林土壤总呼吸(RS)、异养呼吸(Rh)和根呼吸(Rr)都具有明显的单峰曲线季节动态,且峰值均出现在8月;平均RS波动在4.71~7.41μmol/(m^2·s)之间,大小依次为樟子松-落叶松林>杜香-落叶松林>白桦-落叶松林>落叶松纯林>兴安杜鹃-落叶松林,且不同类型兴安落叶松林土壤呼吸存在显著差异(P<0.05);不同类型兴安落叶松林Rh和Rr也存在显著差异(P<0.05),平均Rh表现为樟子松-落叶松林(5.56μmol/(m^2·s))>落叶松纯林(4.64μmol/(m^2·s))>白桦-落叶松林(4.55μmol/(m^2·s))>杜香-落叶松林(4.27μmol/(m^2·s))>兴安杜鹃-落叶松林(3.80μmol/(m^2·s));平均Rr表现为杜香-落叶松林(3.15μmol/(m^2·s))>樟子松-落叶松林(2.98μmol/(m^2·s))>白桦-落叶松林(2.76μmol/(m^2·s))>兴安杜鹃-落叶松林(2.30μmol/(m^2·s))>落叶松纯林(1.97μmol/(m^2·s))。异氧呼吸对土壤呼吸的贡献最大,占61.84%~71.76%,在异养呼吸中,以矿质土壤呼吸(Rm)为主,占土壤总呼吸的46.28%~58.18%,凋落物呼吸(Rl)的贡献只有8.34%~15.57%;Rr的土壤呼吸的贡献率为28.24%~38.16%。RS与土壤10 cm温度(T10)呈显著正相关指数关系,T10可以解释土壤季节性变化的43.6%~57.0%;但RS与土壤10 cm湿度(W10)的相关性因林型而异。【结论】不同类型兴安落叶松林土壤呼吸及其组分之间差异显著;温度是土壤呼吸的主要影响因子,而湿度对土壤呼吸的影响较小。

[Objective]In order to provide scientific basis for further research of carbon release and its influence on the regional climate in cold temperate region of China,the characteristics of soil respiration and its components,and their correlations with soil temperature and humidity were analyzed in larch forests of the Daxing＇an Mountains of northeastern China.[Method]We used LI-6400 chamber tomeasure soil respiration,respiration components and their impacting factors of five typical forest types,which were dominated by larch（pure Larix gmelinii forest,Rhododendron dauricum-Larix gmelinii forest,Ledum palustre Larix gmelinii forest,Betula platyphylla-Larix gmelinii forest,Pinus sylvestris var.mongolica-Larix gmelinii forest） in the north of the Daxing＇an Mountains.[Result]The rates of total soil respiration（RS）,heterotrophic respiration（Rh） and root respiration（Rr） all presented a single-peak curve in growing season,and the peak values all appeared in August for the five kinds of larch forests.The average soil respiration rates of the five communities ranged from 4.71 to 7.41 μmol/（m^2·s）,and their rank was Pinus sylvestris var.mongolica-Larix gmelinii forestLedum palustre-Larix gmelinii forestBetula platyphylla-Larix gmelinii forestpure Larix gmelinii forestRhododendron dauricum-Larix gmelinii forest（P0.05）.The Rhand Rralso had significant differences in the five types of larch forest（P0.05）.The average of Rhranked as Pinus sylvestris var.mongolica-Larix gmelinii forest（5.56μmol/（m^2·s））pure Larix gmelinii forest（4.64 μmol/（m^2·s））Betula platyphylla-Larix gmelinii forest（4.55 μmol/（m^2·s））Ledum palustre-Larix gmelinii forest（4.27 μmol/（m^2·s））Rhododendron dauricum-Larix gmelinii forest（3.80 μmol/（m^2·s））.The average of Rrranked as Ledum palustre-Larix gmelinii forest（3.15 μmol/（m^2·s））Pinus sylvestris var.mongolica-Larix gmelinii forest（2.98 μmol/（m^2·s））Betula platyphylla-Larix gmelinii forest（2.76 μmol/（m^2·s））Rhododendron dauricum-Larix gmelinii forest（2.30 μmol/（m^2·s））pure Larix gmelinii forest（1.97 μmol/（m^2·s））.Rhwas the major component of soil respiration,which accounted for 61.84%-71.76% of the total soil respiration.The soil mineral respiration（Rm） was the main component of Rh,which accounted for46.28%-58.18% of the total soil respiration.However,the soil litterfall respiration（Rl） only accounted for 8.34%-15.57% of the total soil respiration.Rraccounted for 28.24%-38.16% of the total soil respiration.There was a significantly positive correlation（P0.05） between soil respiration rate and the temperature of top 10 cm soil（T_（10））.T_（10） could explain 43.6%-57.0% of seasonal variation for soil respiration.But the correlations between soil respiration rate and soil humidity were different among the five types of larch forests.[Conclusion]There are significant differences among the soil respiration and its components of the five types of larch forests.Temperature is the dominant factor influencing soil respiration,the influence of humidity on soil respiration is weak in the larch forests in the northern Daxing＇an Mountains of northeastern China.