1. Forest planting events present key opportunities to enhance forest adaptation and growth through the selection of appropriate growing materials (seeds and seedlings). Critical to such efforts is knowledge of the climatic distance that seed sources can be moved before significant growth forfeitures are incurred. These limits, referred to here as critical seed transfer distances (CSTD), can be used to identify a potential seed procurement region for any given planting site and can readily incorporate climate change projections.
2. We assembled provenance trial data from a variety of sources and employed transfer functions to derive CSTDs for five major tree species in eastern North America.
3. Optimal height growth at test sites was associated with modest warm-to-cold (i.e. northward) seed transfers of 1.6°C on average. Calculated transfer limits were large, indicating that seed sources could be moved significant climatic distances before height growth was less than 90% relative to that of the local seed source. These broad relationships, which were relatively consistent across species, would allow considerable flexibility in resulting seed transfer systems; however, given the significant uncertainty surrounding climate change—particularly in the location and timing of extreme weather events—prudent application of seed transfer limits may be appropriate.
4. Synthesis: We assembled and analysed a significant amount of provenance data to derive novel information on seed movement limits for five tree species in eastern North America. This information will support forest managers in ongoing efforts to incorporate climate change into forest regeneration operations.

中文翻译：

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北美东部选定树种的关键种子转移距离

1. 造林活动提供了通过选择合适的生长材料（种子和幼苗）来增强森林适应和生长的关键机会。这种努力的关键是了解在发生显着生长丧失之前种子来源可以移动的气候距离。这些限制，在此称为关键种子转移距离 (CSTD)，可用于确定任何给定种植地点的潜在种子采购区域，并可轻松纳入气候变化预测。
2. 我们收集了来自各种来源的起源试验数据，并采用传递函数来推导出北美东部五种主要树种的 CSTD。
3. 测试地点的最佳高度生长与平均 1.6°C 的适度暖到冷（即向北）种子转移有关。计算出的转移限制很大，表明在高度增长低于当地种子源的 90% 之前，种子源可以移动显着的气候距离。这些广泛的关系在物种间相对一致，将为由此产生的种子转移系统提供相当大的灵活性；然而，鉴于围绕气候变化的重大不确定性——尤其是极端天气事件的地点和时间——谨慎应用种子转移限制可能是合适的。
4. 综合：我们收集并分析了大量的来源数据，以获得有关北美东部五种树种的种子移动限制的新信息。这些信息将支持森林管理者不断努力将气候变化纳入森林再生行动。