Integrating O3 influences on terrestrial processes: photosynthetic and stomatal response data available for regional and global modeling
Integrating O3 influences on terrestrial processes: photosynthetic and stomatal response data available for regional and global modeling
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DOI：
10.5194/bg-10-6815-2013
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发表时间：
2013-01-01
期刊：
影响因子：
4.9
通讯作者：
Bonan, G.
中科院分区：
文献类型：
--
作者：
Lombardozzi, D.;Sparks, J. P.;Bonan, G.
植物在光合作用和蒸腾作用过程中，通过控制二氧化碳和水分在生物圈和大气之间的转移，对气候有很强的影响。长期暴露于表面臭氧（O-3）对光合作用和蒸腾作用的影响不同，因为它破坏了气孔导度，气孔导度是控制这两个过程的共同环节，此外叶片的生物化学只影响光合作用。由于O-3在改变植物与大气的相互作用中起着不可或缺的作用，因此有强烈的动机将O-3的影响纳入区域和全球模式。然而，目前还没有使用标准化的O-3参数记录光合作用和气孔导度随时间对O-3暴露的响应的分析，该参数可以很容易地纳入模型。因此，模型通常依赖于从一种或几种与O-3暴露表现出强烈负相关的植物物种的响应中获得的光合作用数据来驱动光合作用和蒸腾速率，而忽略了这两种通量之间的潜在差异。利用来自同行评议文献的数据，我们编制了所有植物类型对慢性O-3暴露的光合和气孔响应，并将同行评议文献中的数据作为O-3累积吸收（CUO）的标准化函数，该函数将O-3通量随时间整合到叶片中。这些数据表明，慢性O-3暴露后，气孔导度下降了约11%，而光合作用单独下降了约21%。尽管这两个变量总体下降，但高方差掩盖了光合作用或气孔导度下降与CUO增加之间的相关性。虽然与CUO的相关关系不易推广，但已有的相关关系表明，光合作用与CUO呈弱负相关，而气孔导度与CUO更多地呈正相关。结果表明，使用仅影响光合作用的强负相关数据的大尺度模型需要重新考虑其响应的普遍性。从这一分析中获得的数据现在可供科学界使用，并可纳入全球模式，以改进对受慢性O-3暴露影响的光合作用、全球陆地碳汇、水文和间接辐射强迫的估计。
Plants have a strong influence on climate by controlling the transfer of carbon dioxide and water between the biosphere and atmosphere during the processes of photosynthesis and transpiration. Chronic exposure to surface ozone (O-3) differentially affects photosynthesis and transpiration because it damages stomatal conductance, the common link that controls both processes, in addition to the leaf biochemistry that only affects photosynthesis. Because of the integral role of O-3 in altering plant interactions with the atmosphere, there is a strong motivation to incorporate the influence of O-3 into regional and global models. However, there are currently no analyses documenting both photosynthesis and stomatal conductance responses to O-3 exposure through time using a standardized O-3 parameter that can be easily incorporated into models. Therefore, models often rely on photosynthesis data derived from the responses of one or a few plant species that exhibit strong negative correlations with O-3 exposure to drive both rates of photosynthesis and transpiration, neglecting potential divergence between the two fluxes. Using data from the peer-reviewed literature, we have compiled photosynthetic and stomatal responses to chronic O-3 exposure for all plant types with data available in the peer-reviewed literature as a standardized function of cumulative uptake of O-3 (CUO), which integrates O-3 flux into leaves through time. These data suggest that stomatal conductance decreases similar to 11% after chronic O-3 exposure, while photosynthesis independently decreases similar to 21 %. Despite the overall decrease in both variables, high variance masked any correlations between the decline in photosynthesis or stomatal conductance with increases in CUO. Though correlations with CUO are not easily generalized, existing correlations demonstrate that photosynthesis tends to be weakly but negatively correlated with CUO while stomatal conductance is more often positively correlated with CUO. Results suggest that large-scale models using data with strong negative correlations that only affect photosynthesis need to reconsider the generality of their response. Data from this analysis are now available to the scientific community and can be incorporated into global models to improve estimates of photosynthesis, global landcarbon sinks, hydrology, and indirect radiative forcing that are influenced by chronic O-3 exposure.