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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Interannual variability of the carbon balance of three different-agedDouglas-fir stands in the Pacific Northwest
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Interannual variability of the carbon balance of three different-agedDouglas-fir stands in the Pacific Northwest

机译：西北太平洋地区三个不同年龄的道格拉斯冷杉林碳平衡的年际变化

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摘要

The seasonal and interannual variability of gross ecosystem photosynthesis (Pg) andecosystem respiration (Re), and their relationships to environmental variables and standcharacteristics were used to explain the variation of eddy-covariance-measured netecosystem productivity (FNEP) of three different-aged Douglas-fir stands located on theeast coast of Vancouver Island in British Columbia, Canada. During the 9-year period,1998-2006, which included a strong El Nifio/La Nina event, the near-end-of-rotationstand (DF49, 57 years old in 2006) was a moderate carbon (C) sink for CO2 with annualFNEP ranging from 267 to 410 g C m-2 yr-1 (mean ± SD, 357 ± 51 g C m-2 yr-1).The pole/sapling stand (HDF88, 18 years old in 2006) was a weak C source (FNEP =—64 ± 75 g C m-2 yr-1), and the recently harvested stand (HDFOO, 6 years old in 2006)was a large C source (FNEP = —515 ± 88 g C 111-2 yr-1) during 2002-2006. Irrespectiveof stand age, all sites responded quite similarly to changes in environmental variablesduring each year. Daily total values of Pg and Re were highest in July—August in all threestands, while daily FNEP peaked during April—June at DF49, May—June at HDF88,and June—July at HDFOO. Reductions in root-zone soil water content decreased both Pgand Re especially during the dry period from May to September, and this effect was morepronounced in the younger stands. Evapotranspiration and dry-foliage surfaceconductance also decreased with decreasing root-zone soil water content whereas wateruse efficiency appeared to be conservative, especially at DF49. Increasing springtemperature had a positive effect on annual Pg and Re but caused a slight decrease inannual FNEP During the summer to autumn transition period, increases in soil watercontent resulted in a greater increase in Re than Pg causing a reduction in FNEp. Theinterannual variation in the C balance was determined mainly by the interannual variationin Re for the near-end-of-rotation stand and Pg for the two younger stands. The resultsindicate that regardless of the stand age, interannual variability in the C balance wasmainly determined by year-to-year variability in spring temperature and water availabilityin late summer.
机译：生态系统总光合作用（Pg）和生态系统呼吸（Re）的季节和年际变化，以及它们与环境变量和标准特征的关系被用来解释涡度协方差测量的生态系统生产力（FNEP）在三个不同年龄的道格拉斯-冷杉站立在加拿大不列颠哥伦比亚省温哥华岛的东海岸。在1998年至2006年这9年期间，其中包括强烈的厄尔尼诺事件/拉尼娜事件，旋转台的近端（DF49，2006年57岁）是一个中等的碳（C）汇，年度FNEP从267到410 g C m-2 yr-1（平均值±SD，357±51 g C m-2 yr-1）。极/树苗架（HDF88，2006年18岁）是弱C碳源（FNEP = -64±75 g C m-2 yr-1），最近收获的林分（HDFOO，2006年6岁）是一个大型碳源（FNEP = -515±88 g C 111-2 yr） -1）在2002-2006年期间。无论展位年龄如何，所有站点每年对环境变量变化的响应都非常相似。 Pg和Re的每日总值在所有三个站的8月中最高，而FNEP在4月至6月的DF49、5月至6月的HDF88和6月至7月的HDFOO达到峰值。根区土壤含水量的减少都降低了Pgand Re，尤其是在五月至九月的干旱时期，这种效应在年轻的林分中更为明显。蒸腾作用和干叶表面电导也随着根区土壤含水量的减少而降低，而水分利用效率似乎是保守的，尤其是在DF49处。春季温度的升高对年度Pg和Re产生积极影响，但导致年度FNEP略有下降。在夏季至秋季的过渡时期，土壤含水量的增加导致Re的增加大于Pg，导致FNEp的减少。 C平衡的年际变化主要由旋转近端林分的Re和两个年轻林分的Pg的年际变化决定。结果表明，不论林分年龄，C平衡的年际变化主要取决于春末和夏末的水利用量的逐年变化。

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