Seasonal patterns and environmental control of carbon dioxide and water vapour exchange in an ecotonal boreal forest
Seasonal patterns and environmental control of carbon dioxide and water vapour exchange in an ecotonal boreal forest
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DOI：
10.1046/j.1365-2486.1999.00281.x
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发表时间：
1999-12-01
影响因子：
11.6
通讯作者：
Valentine, HT
中科院分区：
文献类型：
--
作者：
Hollinger, DY;Goltz, SM;Valentine, HT
在美国缅因州北部森林过渡带南部附近的云杉林中，测量了大气中二氧化碳、水汽和感热通量。夏季，中午的二氧化碳吸收量高于其他北方针叶林，平均约-13 μ mol CO2 m（-2）s（-1）。夏季夜间生态系统呼吸平均约为6 μ mol CO2 m（-2）s（-1），平均温度约为15 ℃。显著的生态系统碳吸收开始与土壤解冻在4月初，突然减少了第一次秋霜在10月初。半小时森林CO2交换主要受入射光合有效光子通量密度（PPFD）的调节。除了冻结温度的阈值效应，有季节效应推断的森林冠层的光合参数。该森林对环境变化的功能反应与其他云杉林相似。与来自北方北方森林的碳损失报告相反，1996年豪兰森林是一个强大的碳汇，储存了约2.1吨C公顷（-1）。
Carbon dioxide, water vapour, and sensible heat fluxes were measured above and within a spruce dominated forest near the southern ecotone of the boreal forest in Maine, USA. Summer, mid-day carbon dioxide uptake was higher than at other boreal coniferous forests, averaging about -13 mu mol CO2 m(-2) s(-1). Nocturnal summer ecosystem respiration averaged approximate to 6 mu mol CO2 m(-2) s(-1) at a mean temperature of approximate to 15 degrees C. Significant ecosystem C uptake began with the thawing of the soil in early April and was abruptly reduced by the first autumn frost in early October. Half-hourly forest CO2 exchange was regulated mostly by the incident photosynthetically active photon flux density (PPFD). In addition to the threshold effects of freezing temperatures, there were seasonal effects on the inferred photosynthetic parameters of the forest canopy. The functional response of this forest to environmental variation was similar to that of other spruce forests. In contrast to reports of carbon loss from northerly boreal forest sites, in 1996 the Howland forest was a strong carbon sink, storing about 2.1 t C ha(-1).