Integrating O3 influences on terrestrial processes: photosynthetic and stomatal response data available for regional and global modeling
[摘要] Plants have a strong influence on climate by controlling the transfer ofcarbon dioxide and water between the biosphere and atmosphere during theprocesses of photosynthesis and transpiration. Chronic exposure to surfaceozone (O3) differentially affects photosynthesis and transpirationbecause it damages stomatal conductance, the common link that controls bothprocesses, in addition to the leaf biochemistry that only affectsphotosynthesis. Because of the integral role of O3 in altering plantinteractions with the atmosphere, there is a strong motivation toincorporate the influence of O3 into regional and global models.However, there are currently no analyses documenting both photosynthesis andstomatal conductance responses to O3 exposure through time using astandardized O3 parameter that can be easily incorporated into models.Therefore, models often rely on photosynthesis data derived from theresponses of one or a few plant species that exhibit strong negativecorrelations with O3 exposure to drive both rates of photosynthesis andtranspiration, neglecting potential divergence between the two fluxes. Usingdata from the peer-reviewed literature, we have compiled photosynthetic andstomatal responses to chronic O3 exposure for all plant types with dataavailable in the peer-reviewed literature as a standardized function ofcumulative uptake of O3 (CUO), which integrates O3 flux into leavesthrough time. These data suggest that stomatal conductance decreases~11% after chronic O3 exposure, while photosynthesisindependently decreases ~21%. Despite the overall decreasein both variables, high variance masked any correlations between the declinein photosynthesis or stomatal conductance with increases in CUO. Thoughcorrelations with CUO are not easily generalized, existing correlationsdemonstrate that photosynthesis tends to be weakly but negatively correlatedwith CUO while stomatal conductance is more often positively correlated withCUO. Results suggest that large-scale models using data with strong negativecorrelations that only affect photosynthesis need to reconsider thegenerality of their response. Data from this analysis are now available tothe scientific community and can be incorporated into global models toimprove estimates of photosynthesis, global land-carbon sinks, hydrology,and indirect radiative forcing that are influenced by chronic O3exposure.
[发布日期] [发布机构]
[效力级别] [学科分类] 地球化学与岩石
[关键词] [时效性]
