Data from: Tradeoffs between three forest ecosystem services across the state of New Hampshire, USA: timber, carbon, and albedo

Forests are more frequently being managed to store and sequester carbon for the purposes of climate change mitigation. Generally, this practice involves long-term conservation of intact mature forests and/or reductions in the frequency and intensity of timber harvests. However, incorporating the influence of forest surface albedo often suggests that long rotation lengths may not always be optimal in mitigating climate change in forests characterized by frequent snowfall. To address this, we investigated tradeoffs between three ecosystem services: carbon storage, albedo-related radiative forcing, and timber provisioning. We calculated optimal rotation length at 498 diverse Forest Inventory and Analysis forest sites in the state of New Hampshire, USA. We found that the average optimal rotation lengths across all sites is 94 years (s = 44), with a large cluster of short optimal rotation lengths that were calculated at high elevations in the White Mountain National Forest. Using a regression tree approach, we found that timber growth, annual storage of carbon, and the difference between annual albedo in mature forest versus a post-harvest landscape were the most important variables that influenced optimal rotation. Additionally we found that the choice of a baseline albedo value for each site significantly altered the optimal rotation lengths across all sites, lowering the mean rotation to 59 years with a high albedo baseline, and increasing the mean rotation to 112 years given a low albedo baseline. Given these results, we suggest that utilizing temperate forests in New Hampshire for climate mitigation purposes through carbon storage and the cessation of harvest is appropriate at a site-dependent level that varies significantly across the state.

为实现气候变化减缓目标，森林经营正愈发普遍地以碳储存与碳固存为核心目标。通常而言，此类经营举措涵盖对完整成熟林的长期保护，以及/或降低木材采伐的频次与强度。然而，若纳入森林地表反照率（albedo）的影响效应，相关分析往往表明：在多雪森林的气候变化减缓实践中，较长的轮伐期未必始终为最优方案。为解决这一问题，本研究探究了三项生态系统服务间的权衡关系：碳储存、反照率相关辐射强迫，以及木材供给。我们针对美国新罕布什尔州的498个多样化森林清查与分析（Forest Inventory and Analysis，FIA）样地，计算了各站点的最优轮伐期。研究结果显示，所有样地的平均最优轮伐期为94年（标准差s=44）；其中怀特山国家森林公园的高海拔区域，存在大量最优轮伐期较短的样地集群。通过回归树分析方法，我们识别出影响最优轮伐期的核心变量依次为：木材生长量、年度碳储存量，以及成熟林与采伐后景观的年度反照率差值。此外，研究还发现，为各站点选取的反照率基准值，会显著改变所有样地的最优轮伐期：当采用高反照率基准值时，平均轮伐期降至59年；而采用低反照率基准值时，平均轮伐期则升至112年。基于上述研究结果，本研究提出：在新罕布什尔州，通过碳储存与停止采伐来利用温带森林实现气候变化减缓目标，需依据站点具体情况确定适配方案，且该方案在全州范围内存在显著差异。