Data from: Stand-level drivers most important in determining boreal forest response to climate change

Forest ecosystems contain several climate-sensitive drivers that respond differentially to changes in climate and climate variability: For example, growth and regeneration processes are “stand-scale” drivers, while natural disturbances operate at “landscape-scale”. The relative contributions of these different scale drivers of change in ecosystems create great uncertainty when simulating potential responses of a forest to changes in climate. Here we assess those contributions, along with harvesting effects, on biomass (both total and of individual species) in the southern boreal forest of Canada under three climate scenarios (RCP 2.6, RCP 4.5 and RCP 8.5). Projections were performed for three future 30-year time periods, in four study regions located on an east-west transect, using a forest landscape model (LANDIS-II), parameterized using a forest patch model (PICUS). Projected future impacts were assessed for each driver of change, and found to vary greatly among regions, species, future period, and forcing scenarios. Fire, and stand-scale climate-induced impacts, had the strongest effects on forest vegetation, as well as on total and species’ biomass under most RCP scenarios, but the largest impacts occurred mostly after 2050, particularly with the RCP 8.5 scenario. The relative importance and trends in species-specific impacts varied, both spatially and according to the different RCP scenarios. Western regions were generally more sensitive to stand-scale climate-induced changes whereas eastern regions were more sensitive to changes in fire regime. Our study also highlights the importance of considering the prevalence of species-level functional traits when assessing the sensitivity of forest landscapes to a given driver of change in the context of increasing anthropogenic climate forcing.

森林生态系统存在多种对气候敏感的驱动因子，这些因子对气候变化及气候变率的响应存在差异：例如，生长与更新过程属于林分尺度（stand-scale）驱动因子，而自然干扰则以景观尺度（landscape-scale）发挥作用。当模拟森林对气候变化的潜在响应时，这些不同尺度的生态系统变化驱动因子的相对贡献，会带来极大的不确定性。
本研究针对加拿大南部寒温带针叶林（boreal forest），在典型浓度路径（Representative Concentration Pathways，RCP）2.6、RCP 4.5及RCP 8.5三种气候情景下，评估上述驱动因子与采伐效应对森林生物量（含总生物量与单物种生物量）的影响。研究依托东西向样带上的4个研究区域，针对3个未来30年时段开展模拟预测；模拟采用森林景观模型（LANDIS-II），并通过森林斑块模型（PICUS）完成参数化配置。
研究对各变化驱动因子的未来影响进行了评估，结果显示其影响在不同区域、物种、未来时段及气候强迫情景下均存在显著差异。在多数RCP情景下，火灾与林分尺度气候诱导效应是对森林植被及总生物量、物种生物量影响最强的因子，但最强影响多出现于2050年之后，尤以RCP 8.5情景最为显著。
单物种影响的相对重要性及其变化趋势，在空间维度与不同RCP情景下均存在差异。西部区域通常对林分尺度的气候诱导变化更为敏感，而东部区域则对火灾制度变化更为敏感。
本研究同时强调，在人为气候强迫日益加剧的背景下，评估森林景观对特定变化驱动因子的敏感性时，需考虑物种功能性状的分布特征。