Differential controls by climate and physiology over the emission rates of biogenic volatile organic compounds from mature trees in a semi-arid pine forest
Differential controls by climate and physiology over the emission rates of biogenic volatile organic compounds from mature trees in a semi-arid pine forest
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DOI：
10.1007/s00442-015-3474-4
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发表时间：
2016-02-01
期刊：
影响因子：
2.7
通讯作者：
Monson, Russell K.
中科院分区：
文献类型：
--
作者：
Eller, Allyson S. D.;Young, Lindsay L.;Monson, Russell K.
干旱有可能影响森林中生物挥发性有机化合物的排放，从而影响大气的氧化能力。我们对这些影响的了解有限，部分原因是缺乏对成熟树木的实地观察以及监测到的BVOC数量较少。我们研究了50至60岁的黄松树在半干旱森林，经历初夏干旱，然后夏末季风雨，并观察排放的五个BVOCs单萜，甲基丁烯醇，甲醇，乙醛和丙酮。我们还构建了一个穿透雨拦截实验，以创建“湿润”和“干燥”的地块。一般来说，树木在干燥的地块表现出降低液流，光合作用，气孔导度，而BVOC排放率不受人工干旱处理。在自然的初夏干旱期间，当光合作用达到千分之一时，生理阈值似乎会被跨越。2 μ mol m（-2）s（-1），电导率为千分之一。0.02 mol m（-2）s（-1）.低于该阈值，BVOC排放与叶片生理学（光合作用和传导性）相关，而BVOC排放与其他物理化学因素（例如，化合物挥发性和组织BVOC浓度），这些因素在过去的研究中已显示会影响排放。在干旱期间，主要是由于减少CO2同化的C BVOC排放的比例损失最高。季节性干旱改变了BVOC排放、光合作用和电导率之间的关系。当干旱是放松的，BVOC排放率主要是由季节性温度，但当季节性干旱是最大的，光合作用和传导的生理过程，最好的解释BVOC排放率下降，可能表明更直接的生理作用，在控制BVOC排放。
Drought has the potential to influence the emission of biogenic volatile organic compounds (BVOCs) from forests and thus affect the oxidative capacity of the atmosphere. Our understanding of these influences is limited, in part, by a lack of field observations on mature trees and the small number of BVOCs monitored. We studied 50- to 60-year-old Pinus ponderosa trees in a semi-arid forest that experience early summer drought followed by late-summer monsoon rains, and observed emissions for five BVOCs-monoterpenes, methylbutenol, methanol, acetaldehyde and acetone. We also constructed a throughfall-interception experiment to create "wetter" and "drier" plots. Generally, trees in drier plots exhibited reduced sap flow, photosynthesis, and stomatal conductances, while BVOC emission rates were unaffected by the artificial drought treatments. During the natural, early summer drought, a physiological threshold appeared to be crossed when photosynthesis a parts per thousand...2 mu mol m(-2) s(-1) and conductance a parts per thousand...0.02 mol m(-2) s(-1). Below this threshold, BVOC emissions are correlated with leaf physiology (photosynthesis and conductance) while BVOC emissions are not correlated with other physicochemical factors (e.g., compound volatility and tissue BVOC concentration) that have been shown in past studies to influence emissions. The proportional loss of C to BVOC emission was highest during the drought primarily due to reduced CO2 assimilation. It appears that seasonal drought changes the relations among BVOC emissions, photosynthesis and conductance. When drought is relaxed, BVOC emission rates are explained mostly by seasonal temperature, but when seasonal drought is maximal, photosynthesis and conductance-the physiological processes which best explain BVOC emission rates-decline, possibly indicating a more direct role of physiology in controlling BVOC emission.