Short rotation plantations are often considered as holding vast potentials for future global bioenergy supply. In contrast to raising biomass harvests in forests, purpose‐grown biomass does not interfere with forest carbon (C) stocks. Provided that agricultural land can be diverted from food and feed production without impairing food security, energy plantations on current agricultural land appear as a beneficial option in terms of renewable, climate‐friendly energy supply. However, instead of supporting energy plantations, land could also be devoted to natural succession. It then acts as a long‐term C sink which also results in C benefits. We here compare the sink strength of natural succession on arable land with the C saving effects of bioenergy from plantations. Using geographically explicit data on global cropland distribution among climate and ecological zones, regionally specific C accumulation rates are calculated with IPCC default methods and values. C savings from bioenergy are given for a range of displacement factors (DFs), acknowledging the varying efficiency of bioenergy routes and technologies in fossil fuel displacement. A uniform spatial pattern is assumed for succession and bioenergy plantations, and the considered timeframes range from 20 to 100 years. For many parameter settings—in particular, longer timeframes and high DFs—bioenergy yields higher cumulative C savings than natural succession. Still, if woody biomass displaces liquid transport fuels or natural gas‐based electricity generation, natural succession is competitive or even superior for timeframes of 20–50 years. This finding has strong implications with climate and environmental policies: Freeing land for natural succession is a worthwhile low‐cost natural climate solution that has many co‐benefits for biodiversity and other ecosystem services. A considerable risk, however, is C stock losses (i.e., emissions) due to disturbances or land conversion at a later time.

中文翻译：

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自然气候解决方案与生物能源：自然演替的碳效益能否与短轮转矮林的生物能源竞争？

短轮伐期种植园通常被认为对未来全球生物能源供应具有巨大潜力。与提高森林生物量收成相反，专门种植的生物量不会干扰森林碳 (C) 储量。如果农业用地可以在不损害粮食安全的情况下用于粮食和饲料生产，那么就可再生、气候友好型能源供应而言，在现有农业土地上种植能源种植园似乎是一种有益的选择。然而，土地也可以用于自然演替，而不是支持能源种植园。然后它充当长期的碳汇，也带来碳效益。我们在这里将耕地自然演替的库强度与种植园生物能源的碳节约效果进行比较。利用全球农田在气候和生态区分布的明确地理数据，使用IPCC默认方法和值计算特定区域的碳积累率。考虑到生物能源路线和化石燃料替代技术的效率不同，生物能源的碳节约量针对一系列置换因子（DF）给出。假设演替和生物能源种植园具有统一的空间格局，考虑的时间范围为 20 至 100 年。对于许多参数设置——特别是更长的时间范围和高DF——生物能源比自然演替产生更高的累积碳节约量。尽管如此，如果木质生物质取代液体运输燃料或天然气发电，那么自然演替在 20-50 年的时间范围内具有竞争力甚至更优越。这一发现对气候和环境政策具有重大影响：释放土地进行自然演替是一种有价值的低成本自然气候解决方案，对生物多样性和其他生态系统服务具有许多共同效益。然而，一个相当大的风险是由于后来的干扰或土地转换而导致碳库损失（即排放）。