Assisted migration has been proposed as a strategy for adaptive management of forest species in response to expected effects of climate change, but it is controversial for several reasons. Tropical dry forests are among the most threatened ecosystems in the world. In Mexico, historically, land-use change and deforestation have been decreasing forest cover, and climate change is shifting the potential distribution of different forest types, exacerbating the risk of local extinctions. Assisted altitudinal migration could be a feasible strategy for reducing local extinctions in response to climate change and lack of landscape connectivity. Our objective was to evaluate survival and growth of Albizia plurijuga and Ceiba aesculifolia, two tropical deciduous forests species in Mexico. We transplanted 4-month-old seedlings to experimental raised beds at three altitudes (2100, 2400 and 2700 m a.s.l.), exceeding their upper regional limit of distribution (2000 m a.s.l.). We also tested seed germination at each altitude. We monitored the experiment for 10 months. For both species, as altitude increased and cold weather was more prevalent, plant performance declined. Within species, differences in individual growth were significant among altitudes. Overall survival was 18.5% for A. plurijuga and 24.5% for C. aesculifolia. Both species had higher survival and better growth at lower altitude, and no seedling emergence at any altitude. We conclude that assisted migration can be implemented for each species by an upward attitudinal shift within, and not exceeding, 400 m beyond their present upper altitudinal limit of distribution. Our results indicate that for many species that show altitudinal gradients at regional scales, unless current climate conditions change, the potential to establish outside their range is minimal.

有人提出将辅助移民作为应对气候变化的预期影响而对森林物种进行适应性管理的一种策略，但由于多种原因，它引起了争议。热带干旱森林是世界上受威胁最大的生态系统之一。在墨西哥，从历史上看，土地利用的变化和森林砍伐一直在减少森林覆盖，气候变化正在改变不同森林类型的潜在分布，加剧了局部灭绝的风险。辅助的高度迁徙可能是减少因气候变化和缺乏景观联系而造成的物种灭绝的可行战略。我们的目标是评估的生存和发展合欢plurijuga和塞巴aesculifolia，是墨西哥的两种热带落叶林物种。我们将4个月大的幼苗移植到三个海拔高度（2100、2400和2700 m asl）的实验性高架床上，超出了它们的区域分布上限（2000 m asl）。我们还测试了每个海拔高度的种子发芽情况。我们监测了10个月的实验。对于这两个物种，随着海拔的升高和寒冷天气的普遍发生，植物性能下降。在物种内部，海拔高度之间的个体生长差异显着。A. plurijuga和C. aesculifolia的总生存率为18.5％。两种物种在较低海拔下都具有较高的存活率和更好的生长，并且在任何海拔下都没有出苗。我们得出的结论是，可以通过在每个物种的当前海拔上限分布范围以内且不超过其400 m内的向上姿态变化，对每个物种实施辅助迁移。我们的结果表明，对于许多在区域尺度上显示出海拔梯度的物种，除非当前的气候条件发生变化，否则在其范围之外建立的可能性很小。