Seasonal controls on interannual variability in carbon dioxide exchange of a near‐end‐of rotation Douglas‐fir stand in the Pacific Northwest, 1997–2006
Seasonal controls on interannual variability in carbon dioxide exchange of a near‐end‐of rotation Douglas‐fir stand in the Pacific Northwest, 1997–2006
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DOI：
10.1111/j.1365-2486.2008.01832.x
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发表时间：
2009-08
影响因子：
11.6
通讯作者：
Baozhang Chen;T. A. Black;N. Coops;P. Krishnan;R. Jassal;C. Brümmer;Z. Nešić
中科院分区：
文献类型：
--
作者：
Baozhang Chen;T. A. Black;N. Coops;P. Krishnan;R. Jassal;C. Brümmer;Z. Nešić
本研究分析了加拿大温哥华岛东海岸太平洋西北道格拉斯冷杉林（2007年58岁）9年的涡动相关（EC）数据，并描述了净生态系统生产力（NEP）、总初级生产力（GPP）和生态系统呼吸（Re）的季节和年际变化，以及这些通量的主要气候控制。NEP、GPP和Re的年值（±SD）分别为357±51、2124±125和1767±146 g C m−2 yr−1，范围分别为267 ~ 410、1592 ~ 2338和1642 ~ 2071 g C m−2 yr−1。春季至初夏（3 - 6月）占年NEP的80%以上，而晚春至初秋（5 - 8月）主要负责其年际变化（~ 80%）。年碳(C)通量年际变率的主要驱动因素是年和春季平均气温（Ta）以及夏末和秋季（7 - 10月）的缺水，此时道格拉斯冷杉林的生长通常是水分有限的。光合有效辐射(Q)和Q与土壤含水量（θ）的组合分别解释了月度GPP方差的85%和91%；每月Re方差的91%和96%分别可以用Ta和Ta与θ的组合来解释。年净碳固存在最温暖和正常降水年较高，而在异常温暖或严重干旱年较低。除受El Niño/La Niña周期强烈影响的1998年和1999年外，年NEP随年平均Ta的增加而显著降低。如果该地点的未来气候遵循与过去40年类似的趋势，则年NEP可能会减少，而年GPP和Re可能会增加。
This study analyzes 9 years of eddy‐covariance (EC) data carried out in a Pacific Northwest Douglas‐fir (Pseudotsuga menzesii) forest (58‐year old in 2007) on the east coast of Vancouver Island, Canada, and characterizes the seasonal and interannual variability in net ecosystem productivity (NEP), gross primary productivity (GPP), and ecosystem respiration (Re) and primary climatic controls on these fluxes. The annual values (± SD) of NEP, GPP and Re were 357 ± 51, 2124 ± 125, and 1767 ± 146 g C m−2 yr−1, respectively, with ranges of 267–410, 1592–2338, and 1642–2071 g C m−2 yr−1, respectively. Spring to early summer (March–June) accounted for more than 80% of annual NEP while late spring to early autumn (May–August) was mainly responsible for its interannual variability (∼80%). The major drivers of interannual variability in annual carbon (C) fluxes were annual and spring mean air temperatures (Ta) and water deficiency during late summer and autumn (July–October) when this Douglas‐fir forest growth was often water‐limited. Photosynthetically active radiation (Q), and the combination of Q and soil water content (θ) explained 85% and 91% of the variance of monthly GPP, respectively; and 91% and 96% of the variance of monthly Re was explained by Ta and the combination of Ta and θ, respectively. Annual net C sequestration was high during optimally warm and normal precipitation years, but low in unusually warm or severely dry years. Excluding 1998 and 1999, the 2 years strongly affected by an El Niño/La Niña cycle, annual NEP significantly decreased with increasing annual mean Ta. Annual NEP will likely decrease whereas both annual GPP and Re will likely increase if the future climate at the site follows a trend similar to that of the past 40 years.