Department of Forest and Wildlife Ecology, University of Wisconsin, 1630 Linden Drive, Madison, Wisconsin 53706, USA.
Ecol Appl. 2010 Mar;20(2):327-46. doi: 10.1890/08-1698.1.
The extent to which current landscapes deviate from the historical range of natural variability (RNV) is a common means of defining and ranking regional conservation targets. However, climate-induced shifts in forest composition may render obsolete restoration strategies and conservation targets based on historic climate conditions and disturbance regimes. We used a spatially explicit forest ecosystem model, LANDIS-II, to simulate the interaction of climate change and forest management in northeastern Minnesota, USA. We assessed the relevance of restoration strategies and conservation targets based on the RNV in the context of future climate change. Three climate scenarios (no climate change, low emissions, and high emissions) were simulated with three forest management scenarios: no harvest, current management, and a restoration-based approach where harvest activity mimicked the frequency, severity, and size distribution of historic natural disturbance regimes. Under climate change there was a trend toward homogenization of forest conditions due to the widespread expansion of systems dominated by maple (Acer spp.). White spruce (Picea glauca), balsam fir (Abies balsamea), and paper birch (Betula papyrifera) were extirpated from the landscape irrespective of management activity; additional losses of black spruce (P. mariana), red pine (Pinus resinosa), and jack pine (P. banksiana) were projected in the high-emissions scenario. In the restoration management scenario, retention and conversion to white pine (P. strobus) restricted maple expansion. But, widespread forest loss in the restoration scenario under high-emissions projections illustrates the potential pitfalls of implementing an RNV management approach in a system that is not compositionally similar to the historic reference condition. Given the uncertainty associated with climate change, ensuring a diversity of species and conditions within forested landscapes may be the most effective means of ensuring the future resistance of ecosystems to climate-induced declines in productivity.
当前景观与历史自然变异性范围（RNV）的偏离程度是定义和划分区域保护目标的常用方法。然而，由于气候引起的森林组成变化，基于历史气候条件和干扰制度的恢复策略和保护目标可能变得过时。我们使用空间明确的森林生态系统模型 LANDIS-II 来模拟美国明尼苏达州东北部的气候变化和森林管理的相互作用。我们评估了基于 RNV 的恢复策略和保护目标在未来气候变化背景下的相关性。我们模拟了三个气候情景（没有气候变化、低排放和高排放）和三种森林管理情景：没有采伐、当前管理和基于恢复的方法，其中采伐活动模拟了历史自然干扰制度的频率、严重程度和大小分布。在气候变化下，由于以枫木（Acer spp.）为主的系统广泛扩张，森林条件呈现出趋同的趋势。无论管理活动如何，白云杉（Picea glauca）、香脂冷杉（Abies balsamea）和纸皮桦（Betula papyrifera）都从景观中灭绝；在高排放情景下，黑云杉（P. mariana）、红松（Pinus resinosa）和火炬松（P. banksiana）的损失预计会进一步增加。在恢复管理情景中，保留和转换为白松（P. strobus）限制了枫木的扩张。但是，在高排放预测下，恢复情景中的广泛森林损失说明了在与历史参考条件组成不同的系统中实施 RNV 管理方法的潜在陷阱。考虑到气候变化的不确定性，确保森林景观内物种和条件的多样性可能是确保生态系统未来对生产力下降的气候影响具有抵抗力的最有效手段。
