Physiological responses of a black spruce forest to weather
Physiological responses of a black spruce forest to weather
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DOI：
10.1029/97jd01111
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发表时间：
1997-12-26
影响因子：
4.4
通讯作者：
Wofsy, SC
中科院分区：
文献类型：
--
作者：
Goulden, ML;Daube, BC;Wofsy, SC
我们使用涡度协方差测量大气和黑云杉（Picea mariana）森林在马尼托巴16,500小时，从1994年3月16日至1996年10月31日之间的CO2净交换。然后，我们分区净交换到总光合作用和呼吸，估计白天呼吸作为温度的函数，并使用这些数据来定义森林对天气的生理反应。林分的年总生产量和年呼吸量均在8 t C ha（-1）yr（-1）左右。光合和呼吸响应在冬季降低，春季随气候变暖而恢复，夏季变化不大。在盛夏，当Q（10）约为2时，呼吸随空气温度（T-空气）增加，在15 ℃时，其速率为2-8 μ mol m（-2）s（-1）。在强光下（光子通量密度（PPFD）大于600 μ mol m（-2）s（-1）），总光合作用在T-air < 0 ℃时可以忽略不计，从0 ℃到14 ℃随T-air线性增加，并且对T-air > 14 ℃相对不敏感。在T-air > 14 ℃时，总CO2吸收量随着光照的增加而增加，在生态系统水平的量子产率为0.05 mol CO2 mol（-1）光子时，在PPFD大于500-700 μ mol m（-2）s（-1）时，吸收速率为8-18 μ mol m（-2）s（-1）时达到饱和。光合作用在夏季没有出现限制高蒸发需求或土壤水分枯竭。
We used eddy covariance to measure the net exchange of CO2 between the atmosphere and a black spruce (Picea mariana) forest in Manitoba for 16,500 hours from March 16, 1994 to October 31, 1996. We then partitioned net exchange into gross photosynthesis and respiration by estimating daytime respiration as a function of temperature, and used these data to define the physiological responses of the forest to weather. The annual rates of gross production and respiration by the forest were both around 8 t C ha(-1) yr(-1). Both photosynthetic and respiratory response were reduced in winter, recovered with warming in spring, and varied little in summer. Respiration in mid summer increased with air temperature (T-air) at a Q(10) of around 2 to a rate of 2-8 mu mol m(-2) s(-1) at 15 degrees C. Gross photosynthesis at high light (photon flux density (PPFD) greater than 600 mu mol m(-2) s(-1)) was negligible at T-air < 0 degrees C, increased linearly with T-air from 0 degrees to 14 degrees C, and was relatively insensitive to T-air > 14 degrees C. Gross CO2 uptake at T-air > 14 degrees C increased with increasing light at an ecosystem-level quantum yield of 0.05 mol CO2 mol(-1) photons before saturating at an uptake rate of 8-18 mu mol m(-2) s(-1) at PPFDs greater than 500-700 mu mol m(-2) s(-1). Photosynthesis in summer did not appear limited by high evaporative demand or soil water depletion.