兴安落叶松林土壤呼吸及组分的变化特征

Variation characteristics of soil respiration and its components in Larix Gmelinii forest

采用挖壕法断根对兴安落叶松(Larix gmelinii)林土壤呼吸的组分进行分离,利用静态箱/碱液吸收法对土壤呼吸以及各组分的呼吸速率及10 cm土层的土壤温度和土壤含水量进行测定。研究兴安落叶松林土壤呼吸及其组分的日动态和季动态变化特征,阐明大兴安岭地区兴安落叶松林土壤呼吸及其组分的变化规律及其与土壤温度、土壤含水量两个影响因子之间的关系。研究结果显示,①兴安落叶松林土壤呼吸、异养呼吸和自养呼吸都呈现明显的日变化和季节变化规律,日变化曲线均呈单峰型,自养呼吸速率的日变化较平缓,其最大值与土壤呼吸、异养呼吸和土壤温度的时间比较出现滞后现象:在生长季土壤呼吸和异养呼吸月平均呼吸速率值的排列顺序依次为:7月>8月>9月>6月,而自养呼吸月平均呼吸速率值的排列顺序依次为:8月>7月>9月>6月。②兴安落叶松林中土壤呼吸速率、异养呼吸速率和自养呼吸速率与10 cm土壤温度之间均成指数相关关系,通过计算得出Q10值分别为1.69、1.97和1.24,与其他地区的研究结果相比温度敏感性偏低。土壤呼吸、异养呼吸和自养呼吸与土壤含水量有相关性但不显著。③异养呼吸和自养呼吸对土壤总呼吸的贡献率分别约为63%、37%,该地区土壤异养呼吸所占比例接近于自养呼吸的两倍。

In the present study, we use trenching method to separate heterotrophic and autotrophic respiration in the Larix gmelinii forest and measure soil temperature and soil water content at 10 cm soil layer. The daily and seasonal variation of soil respiration and their composition were investigated in the Larix gmelinii forest. The results are showed as follows： ①Soil respiration, heterotrophic and autotrophic respiration indicated an obvious daily and seasonal variation trend and the diurnal variation of soil total respiration and its components was described as a single-peak curve. Compared with soil respiration and heterotrophic respiration, the daily variation of autotrophic respiration is relatively fiat and its maximum appeared hysteresis phenomenon. During the growing season, the ranking for the monthly average soil and heterotrophic respiration rate is July〉 August〉 September〉 June, and for the autotrophic respiration is August〉July 〉September 〉June. ②The total soil respiration rate and its components were exponentially related to the soil temperature in 10 cm soil layer. The Ql0 values of total soil respiration, heterotrophic respiration, and autotrophic respiration calculated based on the soil temperature were 1.69, 1.97 and 1.24, suggesting that the temperature sensitivity was significantly lower than that of the other regions. However the soil respiration was not significantly influenced by the soil water content. ③The contribution rate of heterotrophic respiration and autotrophic respiration to total soil respiration estimated in the growing season were 63% and 37%, indicating that the contribution rate ofheterotrophic respiration was twice autotrophic respiration in this area.