Department of Sustainable Agriculture Sciences, Rothamsted Research, Harpenden, UK.
Department of Biological and Environmental Sciences, School of Life and Medical Sciences, University of Hertfordshire, Hatfield, UK.
Ann Bot. 2019 Oct 29;124(4):531-542. doi: 10.1093/aob/mcz006.
Bioenergy is central for the future energy mix to mitigate climate change impacts; however, its intricate link with the water cycle calls for an evaluation of the carbon-water nexus in biomass production. The great challenge is to optimize trade-offs between carbon harvest and water use by choosing cultivars that combine low water use with high productivity.
Regional scenarios were simulated over a range of willow genotype × environment interactions for the major UK soil × climate variations with the process-based model LUCASS. Soil available water capacity (SAWC) ranged from 51 to 251 mm and weather represented the north-west (wet, cool), north-east (dry, cool), south-west (wet, warm) and south-east (dry, warm) of the UK. Scenario simulations were evaluated for small/open narrow-leaf (NL) versus large/closed broad-leaf (BL) willow canopy phenotypes using baseline (1965-89) and warmer recent (1990-2014) weather data.
The low productivity under baseline climate in the north could be compensated by choosing BL cultivars (e.g. 'Endurance'). Recent warmer climate increased average productivity by 0.5-2.5 t ha-1, especially in the north. The modern NL cultivar 'Resolution' had the smallest and most efficient water use. On marginal soils (SAWC <100 mm), yields remained below an economic threshold of 9 t ha-1 more frequently under baseline than recent climate. In the drought-prone south-east, 'Endurance' yielded less than 'Resolution', which consumed on average 17 mm year-1 less water. Assuming a planting area of 10 000 ha, in droughty years between 1.3 and 4.5 × 106 m3 of water could be saved, with a small yield penalty, for 'Resolution'.
With an increase in air temperature and occasional water scarcities expected with climate change, high-yielding NL cultivars should be the preferred choice for sustainable use of marginal lands and reduced competition with agricultural food crops.
生物能源对于减轻气候变化影响的未来能源组合至关重要；然而，它与水循环的复杂联系要求对生物质生产中的碳-水关系进行评估。最大的挑战是通过选择既能节水又能高产的品种，优化碳收获和水利用之间的权衡。
利用基于过程的模型 LUCASS，对英国主要土壤-气候变化范围内的一系列柳树基因型-环境互作进行了区域情景模拟。土壤有效含水量（SAWC）范围为 51-251mm，天气代表英国西北部（潮湿、凉爽）、东北部（干燥、凉爽）、西南部（潮湿、温暖）和东南部（干燥、温暖）。利用 1965-89 年的基线天气数据和较温暖的近期（1990-2014 年）天气数据，对小/开阔窄叶（NL）与大/封闭宽叶（BL）柳树冠层表型的情景模拟进行了评估。
在北部的基线气候条件下，生产力较低，但可以通过选择 BL 品种（如“耐力”）来弥补。最近较温暖的气候使平均生产力提高了 0.5-2.5t/ha-1，尤其是在北部。现代 NL 品种“分辨率”用水量最小，效率最高。在边缘土壤（SAWC<100mm）上，在基线气候下，产量低于经济阈值（9t/ha-1）的情况比近期气候更为频繁。在易发生干旱的东南部，“耐力”的产量低于“分辨率”，后者平均每年耗水 17mm 左右。假设种植面积为 10000ha，在干旱年份，“分辨率”可节省 1.3-4.5×106m3 的水，产量略有下降。
随着气候变化导致气温上升和偶尔出现水资源短缺，高产量的 NL 品种应成为可持续利用边缘土地和减少与农业粮食作物竞争的首选。
