Concern about climate change has motivated France to reduce its reliance on fossil fuel by setting targets for increased biomass-based renewable energy production. This study quantifies the carbon costs and benefits for the French forestry sector in meeting these targets. A forest growth and harvest simulator was developed for French forests using recent forest inventory data, and the wood-use chain was reconstructed from national wood product statistics. We then projected wood production, bioenergy production, and carbon balance for three realistic intensification scenarios and a business-as-usual scenario. These intensification scenarios targeted either overstocked, harvest-delayed or currently actively managed stands. All three intensification strategies produced 11.6–12.4 million tonnes of oil equivalent per year of wood-based energy by 2026, which corresponds to the target assigned to French wood-energy to meet the EU 2020 renewable energy target. Sustaining this level past 2026 will be challenging, let alone further increasing it. Although energy production targets can be reached, the management intensification required will degrade the near-term carbon balance of the forestry sector, compared to continuing present-day management. Even for the best-performing intensification strategy, i.e., reducing the harvest diameter of actively managed stands, the carbon benefits would only become apparent after 2040. The carbon balance of a strategy putting abandoned forests back into production would only break even by 2055; the carbon balance from increasing thinning in managed but untended stands would not break even within the studied time periods, i.e. 2015–2045 and 2046–2100. Owing to the temporal dynamics in the components of the carbon balance, i.e., the biomass stock in the forest, the carbon stock in wood products, and substitution benefits, the merit order of the examined strategies varies over time. No single solution was found to improve the carbon balance of the forestry sector by 2040 in a way that also met energy targets. We therefore searched for the intensification scenario that produces energy at the lowest carbon cost. Reducing rotation time of actively managed stands is slightly more efficient than targeting harvest-delayed stands, but in both cases, each unit of energy produced has a carbon cost that only turns into a benefit between 2060 and 2080.

中文翻译：

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法国生物质能生产目标的碳成本和收益。

对气候变化的关注促使法国通过设定增加基于生物质的可再生能源生产的目标来减少对化石燃料的依赖。这项研究量化了法国林业部门实现这些目标所需的碳成本和收益。使用最近的森林清单数据为法国森林开发了森林生长和采伐模拟器，并从国家木材产品统计数据重建了木材使用链。然后，我们针对三种现实的集约化情景和“一切照旧”情景预测了木材产量，生物能源产量和碳平衡。这些集约化方案针对的是积压，收割延迟或当前积极管理的林分。到2026年，所有这三种强化战略每年产生的木质能源油当量为11.6-1240万吨，这对应于分配给法国木材能源的目标，以实现欧盟2020年的可再生能源目标。在2026年之前维持这一水平将是一个挑战，更不用说进一步提高它了。尽管可以达到能源生产的目标，但与目前的持续管理相比，需要加强管理将降低林业部门的近期碳平衡。即使采用表现最佳的集约化战略，即减少主动管理林分的采伐直径，碳效益也只会在2040年后显现。将废弃森林重新投入生产的战略的碳平衡将仅在2055年达到收支平衡。在研究的时间段内（即2015-2045年和2046-2100年），受管理但无人看管的林木间伐减少导致的碳平衡不会收支平衡。由于碳平衡各组成部分的时间动态，即森林中的生物量储备，木制品中的碳储备和替代效益，所研究策略的优劣顺序随时间而变化。到2040年，没有找到一种能同时达到能源目标的方法来改善林业部门的碳平衡。因此，我们搜索了以最低碳成本生产能源的集约化方案。减少主动管理的林分的轮换时间比针对延迟收获的林分更有效率，但是在两种情况下，每产生的能量单位所产生的碳成本仅在2060年至2080年之间变成一种收益。和替代利益，所考察策略的优劣顺序随时间而变化。到2040年，没有找到一种能同时达到能源目标的方法来改善林业部门的碳平衡。因此，我们搜索了以最低碳成本生产能源的集约化方案。减少主动管理的林分的轮换时间比针对延迟收获的林分更有效率，但是在两种情况下，每产生的能量单位所产生的碳成本仅在2060年至2080年之间变成一种收益。和替代利益，所考察策略的优劣顺序随时间而变化。到2040年，没有找到一种能同时达到能源目标的方法来改善林业部门的碳平衡。因此，我们搜索了以最低碳成本产生能源的集约化方案。减少主动管理的林分的轮换时间比针对延迟收获的林分更有效率，但是在两种情况下，每产生的能量单位所产生的碳成本仅在2060年至2080年之间变成一种收益。