气候变化对中国主要农作物秸秆资源的影响

Impacts of Climate Change on Residue Resources of Main Crops in China

生物质能在缓解能源紧张,降低气候变化影响方面具有广阔的发展前景。农作物秸秆作为其丰富重要的原料之一,它的有效开发和利用,将对我国生物质资源的综合利用有重要影响。气候变化会影响农作物秸秆产量,本研究利用CERES作物模型模拟了基本气候BS情景下(1961年-1990年)和SRES温室气体排放方案下B2情景的(2011年-2100年)我国三大粮食作物水稻、小麦、玉米的秸秆生产量,分析并预测了未来气候变化对其秸秆生产量的影响,结果表明:①作物秸秆生产总量表现为先降低(2020s)后增加(2050s、2080s)的趋势,其中水稻的秸秆单产和总量将下降,而小麦和玉米的秸秆单产、总量则有增加趋势,尤其是小麦增加幅度更大;②未来气候变化将增大作物秸秆生产总量的年际波动,影响秸秆利用量的稳定性;③华北地区是未来三大作物秸秆总量增加的主要区域,有利于秸秆资源的开发和利用,而东北的东部地区秸秆总量表现为大幅度的降低。本文成果属初步研究,存在一定的不确定性,今后需要继续深入探讨,逐步降低研究中的不确定性。

Concerns about increasing greenhouse gases concentration in the atmosphere and sustainability of fossil fuel use in the context of advance in biomass conversion technology have renewed interest in crop residue as a type of biofuel. This would be greatly useful for securing energy supply and mitigating global warming as well. Crop residue, as a major biomass energy used in China’s rural areas, may play a more important role in contributing to renewable energy needs due to its greater quantity produced each year. Therefore, its magnitude and geographical distribution need to be better understood, particularly the impacts induced by climate change. Climate change might impose impacts on crop residue through inducing positive or negative effects on potential biomass and yield, or through changing its geographical patterns. Three major crops （i.e., maize, rice and wheat） produce a sufficient quantity of residue each year for supporting commercial production in China. We simulated biomass yield of the three crops by the CERES crop model at a 50 km×50 km resolution, and subsequently computed the mass quantity of harvested residues for the whole country. Magnitude and spatial distribution were extensively investigated under two scenarios： with and without climate change. A climate scenario （BS, 1961-1990） simulated by PRECIS regional climate model with current greenhouse gases concentration （380 ppm） was used to represent current climate, and a scenario （B2, 2011-2100） with low to middle greenhouse gases emission （CO2 concentration increases from 388 ppm in 2011 to 604 ppm in 2100） stands for climate change. Results demonstrate that 1） the quantity of the three crop residue of China would decrease in the 2020s, but increase in the 2050s and 2080s. Climate change would likely decrease the biomass yields and residues on average for rice. Residues of maize, particularly for wheat, would reveal improvement in productivity under climate change. Reasons for such different changes between crops could be ascribed to various combinations of geographical distributions of crops, climatic characteristics, management practices, and asymmetric impacts of global warming on phenology of crops （i.e., vegetative or reproductive period）; 2） the inter-annual variation in residue yields would increase in the future. This highlights an increasing variability and possibility of unstable biomass supply due to global warming; and 3） geographical patterns of biomass would vary greatly and regionally. The Northern China Plain would present the largest increase in gains under climate change due in part to its largest proportion of winter wheat cultivation whose biomass and yield can benefit substantially from climate warming. The yield of crop residue in Northeast China, particularly over the eastern part, would decrease dramatically under climate change. This is as a consequence of a larger rice production area, and rice biomass and yield being constrained by global warming.