Monson Russell K, Trahan Nicole, Rosenstiel Todd N, Veres Patrick, Moore David, Wilkinson Michael, Norby Richard J, Volder Astrid, Tjoelker Mark G, Briske David D, Karnosky David F, Fall Ray
Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.
Philos Trans A Math Phys Eng Sci. 2007 Jul 15;365(1856):1677-95. doi: 10.1098/rsta.2007.2038.
Coupled surface-atmosphere models are being used with increased frequency to make predictions of tropospheric chemistry on a 'future' earth characterized by a warmer climate and elevated atmospheric CO2 concentration. One of the key inputs to these models is the emission of isoprene from forest ecosystems. Most models in current use rely on a scheme by which global change is coupled to changes in terrestrial net primary productivity (NPP) which, in turn, is coupled to changes in the magnitude of isoprene emissions. In this study, we conducted measurements of isoprene emissions at three prominent global change experiments in the United States. Our results showed that growth in an atmosphere of elevated CO2 inhibited the emission of isoprene at levels that completely compensate for possible increases in emission due to increases in aboveground NPP. Exposure to a prolonged drought caused leaves to increase their isoprene emissions despite reductions in photosynthesis, and presumably NPP. Thus, the current generation of models intended to predict the response of isoprene emission to future global change probably contain large errors. A framework is offered as a foundation for constructing new isoprene emission models based on the responses of leaf biochemistry to future climate change and elevated atmospheric CO2 concentrations.
耦合的地表-大气模型正越来越频繁地用于预测“未来”地球上对流层化学，这个“未来”地球的特征是气候变暖以及大气二氧化碳浓度升高。这些模型的关键输入之一是森林生态系统中异戊二烯的排放。当前使用的大多数模型依赖于一种方案，即全球变化与陆地净初级生产力（NPP）的变化相耦合，而陆地净初级生产力的变化又与异戊二烯排放幅度的变化相耦合。在本研究中，我们在美国的三个重要全球变化实验中对异戊二烯排放进行了测量。我们的结果表明，在二氧化碳浓度升高的大气中生长会抑制异戊二烯排放，抑制程度完全抵消了由于地上NPP增加可能导致的排放增加。长时间干旱胁迫会使叶片增加异戊二烯排放，尽管光合作用以及推测的NPP有所降低。因此，当前旨在预测异戊二烯排放对未来全球变化响应的模型可能存在很大误差。本文提供了一个框架，作为基于叶片生物化学对未来气候变化和大气二氧化碳浓度升高的响应构建新的异戊二烯排放模型的基础。
