Manunta Paolo, Grant Robert F, Feng Yongshen, Kimball Bruce A, Pinter Paul J, La Morte Robert L A, Hunsaker Douglas J, Wall D J
Department of Renewable Resources, University of Alberta, Canada.
Int J Biometeorol. 2002 Feb;46(1):9-21. doi: 10.1007/s004840100105.
The rationale for this study is found in the probable higher temperatures and changes in rainfall patterns that are expected in the future as a result of increasing levels of CO2 in the atmosphere. In particular, higher air temperatures may cause an increase in evapotranspiration demand while a reduction in rainfall could increase the severity and duration of drought in arid and semi-arid regions. Representation of the water transfer scheme includes water uptake by roots and the interaction between evapotranspiration and CO2 enrichment. The predicted response of a spring wheat (Triticum aestivum L. cv. Yecora rojo) canopy in terms of energy exchange processes to elevated atmospheric CO2 level was tested against measurements collected at the FACE (Free Air Enrichment Experiment) site in 1994. Simulated and measured canopy conductances were reduced by about 30% under elevated [CO2] under optimum conditions of water supply. Reductions in latent heat fluxes under elevated instead of ambient [CO2] caused reductions in both simulated and measured seasonal water use of 6% under optimum and 2% under suboptimum irrigation. The soil-plant-atmosphere water transfer scheme proposed here offers several advances in the simulation of land surface interactions. First, the stomatal resistance model minimizes assumptions in existing land surface schemes about the effects of interactions among environmental conditions (radiation, temperature, CO2) upon stomatal behavior. These interactions are resolved in the calculation of CO2 in which processes are already well understood.
本研究的理论依据在于，由于大气中二氧化碳水平不断上升，预计未来气温可能升高，降雨模式也会发生变化。特别是，较高的气温可能会导致蒸散需求增加，而降雨减少可能会加剧干旱和半干旱地区干旱的严重程度并延长其持续时间。水分传输方案的表示包括根系对水分的吸收以及蒸散与二氧化碳富集之间的相互作用。根据1994年在自由空气富集实验（FACE）站点收集的测量数据，测试了春小麦（Triticum aestivum L. cv. Yecora rojo）冠层在能量交换过程方面对大气二氧化碳水平升高的预测响应。在供水最佳条件下，在高二氧化碳浓度下，模拟和测量的冠层导度降低了约30%。与环境二氧化碳浓度相比，高二氧化碳浓度下潜热通量的降低导致在最佳灌溉条件下模拟和测量的季节性用水量减少了6%，在次优灌溉条件下减少了2%。这里提出的土壤-植物-大气水分传输方案在陆地表面相互作用的模拟方面有几个进步。首先，气孔阻力模型尽量减少了现有陆地表面方案中关于环境条件（辐射、温度、二氧化碳）之间的相互作用对气孔行为影响的假设。这些相互作用在二氧化碳的计算中得到了解决，而其中的过程已经得到了很好的理解。
