近地层O_3和CO_2浓度变化对冬小麦影响的数值模拟:Ⅱ模拟结果和分析

NUMERICAL SIMULATION STUDY ON THE IMPACTS OF CHANGES OF TROPOSHERE O_3 AND CO_2 CONCENTRATIONS ON WINTER WHEAT: ⅡSIMULATION RESULTS AND ANALYSES

针对CO2和O3浓度变化对冬小麦影响,改进了农田生态系统碳氮生物化学模型(DNDC),并利用模型模拟了O3和CO2浓度变化对冬小麦生长发育和产量的影响,检验了模型的模拟效果。通过对原DNDC模型适用性的调整,使之适用于固城站,为进一步改进作物模型打下了可靠的基础。通过试验资料验证表明,模型较好地反映了O3和CO2浓度变化对冬小麦生长发育和产量形成的影响。通过敏感性分析得出,模型对温度变化反映灵敏;在CO2浓度倍增情况下,O3浓度变化对冬小麦的复合影响分析看出,一定浓度范围内,CO2可缓解O3对作物影响的负效应,O3对CO2带来的正效应有削弱作用。

With the rapid development of industrialization and urbanization, the increase of the troposphere ozone and carbon dioxide concentration at striking rates has adverse effects on biosphere, especially on crops. It is generally accepted that the increase of carbon dioxide concentration has beneficial effects on plant productivity while ozone is reported as the air pollutant most damaging to agricultural crops and other plant. The Model of Carbon and Nitrogen Biogeochemistry in Agroecosystems (DNDC) is adapted to evaluate simultaneously impacts of climate change on winter wheat. Growth development and yield formation of winter wheat under different O_3 and CO_2 concentration conditions were simulated with the improved DNDC model which structure has been described in another paper. Through adjusting the DNDC model applicability, winter wheat growth and development in Gucheng station was simulated well in 1993 and 1999, which was in favor of modifying the model further. The model was validated against experiment observation, including development stage data, leaf area index, single organ biomass and total aboveground biomass. Sensitivity tests demonstrated that the simulated results in development stage, biomass were sensitive to temperature change. The main conclusions of the paper were as follows: (1) Growth and yield of winter wheat under CO_2 concentration of 500×10 -6(V/V), 700×10 -6(V/V) and the current ozone concentration was simulated respectively by the model. The results were well fitted with the observed values from the OTCs experiment. The results indicated that the increase of concentration of CO_2 may improve the growth of winter wheat and elevate the yield. (2) The growth and yield of winter wheat under O_3 concentration of 50×10 -9(V/V),100×10 -9(V/V),200×10 -9(V/V) and the current CO_2 concentration were simulated respectively by the model. The simulated curves of the growths of stem, leaf and spike organs as well as leaf area index were well in agreement with the observed data. The results revealed that ozone has a detrimental effect on the growth and yield of winter wheat. Ozone accelerated the process of leaf senescence and caused the loss of the yield. Under very high ozone concentration, crops were affected dramatically and even dead. (3) At last, by the model the possible effects of changes of air temperature and the combined effects of O_3 and CO_2 were estimated respectively. The results showed that doubled CO_2 concentration may alleviate the negative effect of O_3 on biomass and yield of winter wheat when ozone concentration was about 70×10 -9～80×10 -9(V/V). The obverse effects of CO_2 were less than the adverse effects of O_3 when the concentration of ozone is up to 100×10 -9(V/V). Future work should determine whether it is applied to other species by adjusting the values of related parameters, and whether the model can be adapted to predict ozone effects on crops in farmland environment.