Bond-Lamberty Ben, Wang Chuankuan, Gower Stith T
Department of Forest Ecology and Management, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI 53706, USA.
Tree Physiol. 2004 Dec;24(12):1387-95. doi: 10.1093/treephys/24.12.1387.
We quantified the contributions of root respiration (RC) and heterotrophic respiration to soil surface CO2 flux (RS) by comparing trenched and untrenched plots in well-drained and poorly drained stands of a black spruce (Picea mariana (Mill.) BSP) fire chronosequence in northern Manitoba, Canada. Our objectives were to: (1) test different equations for modeling RS as a function of soil temperature; and (2) model annual RS and RC for the chronosequence from continuous soil temperature measurements. The choice of equation to model RS strongly affected annual RS and RC, with an Arrhenius-based model giving the best fit to the data, especially at low temperatures. Modeled values of annual RS were positively correlated with soil temperature at 2-cm depth and were affected by year of burn and trenching, but not by soil drainage. During the growing season, measured RC was low in May, peaked in late July and declined to low values by the end of the growing season. Annual RC was < 5% of RS in the recently burned stands, approximately 40% in the 21-year-old stands and 5-15% in the oldest (152-year-old) stands. Evidence suggests that RC may have been underestimated in the oldest stands, with residual root decay from trenching accounting for 5-10% of trenched plot RS at most sites.
我们通过比较加拿大曼尼托巴省北部黑云杉（Picea mariana (Mill.) BSP）火烧时间序列中排水良好和排水不良林分中挖沟和未挖沟样地，量化了根系呼吸（RC）和异养呼吸对土壤表面二氧化碳通量（RS）的贡献。我们的目标是：（1）测试将RS作为土壤温度函数进行建模的不同方程；（2）根据连续的土壤温度测量值，对时间序列的年RS和RC进行建模。用于模拟RS的方程选择对年RS和RC有很大影响，基于阿伦尼乌斯的模型对数据拟合最佳，尤其是在低温时。年RS的模拟值与2厘米深度处的土壤温度呈正相关，并且受火烧年份和挖沟的影响，但不受土壤排水的影响。在生长季节，实测RC在5月较低，7月下旬达到峰值，并在生长季节结束时降至低值。在最近火烧的林分中，年RC小于RS的5%，在21年生林分中约为40%，在最老的（152年生）林分中为5 - 15%。有证据表明，在最老的林分中RC可能被低估了，在大多数地点，挖沟导致的残留根系腐烂最多占挖沟样地RS的5 - 10%。
