Data from: Assisted migration of cloud forest trees: Unearthing the effects of climatic transfer distance

We planted 30 seedlings of 13 shade-tolerant tropical montane cloud forest
tree species in eight forest sites (3120 seedlings in total) along an
elevation gradient (1250 to 2429 m a.s.l.) in central-eastern Mexico. We
recorded sapling survival and relative growth rate in height (RGRh) and
diameter (RGRd) after eight years. We tested the survival and growth
response for all species together to the effect of Climatic Transfer
Distance (CTD; the difference between the historical climate at the seed
source and the current climate at translocation sites) in terms of mean
annual temperature (CTD_MAT), maximum and minimum annual temperatures
(CTD_Tmax and CTD_Tmin), mean annual precipitation (CTD_MAP), and climate
moisture deficit (CTD_CMD). We also tested the sapling response to the
climatic variables at the translocation site. We found evidence to support
the decline, although slight, in tree sapling survival and growth across
tree species with increasing CTD, thus supporting the hypothesis of a
reduction in performance with increasing distance between the climate to
which tree species are adapted (historic climate of seed origin) and that
at the new translocation sites. Our results support a higher mortality
risk caused by increasing CTD in MAP and MAT and a decline in growth
caused by the increasing CTD in MAT, Tmax, MAP, and CMD. Although high
variation occurred among species, this general pattern still emerged and
was consistent for all the climatic variables.

本研究于墨西哥中东部沿海拔梯度（1250至2429米，m a.s.l.）的8个森林样地内，定植了13种耐阴热带山地云雾林树种的幼苗，每个树种定植30株，总计3120株幼苗。于定植8年后，记录了幼树的存活率，以及株高相对生长率（RGRh）与基径相对生长率（RGRd）。我们以所有受试物种为整体，探究了其存活与生长对气候转移距离（Climatic Transfer Distance，简称CTD）的响应；CTD指种子来源地的历史气候与移栽样地当前气候之间的差值，具体涵盖年平均气温转移距离（CTD_MAT）、年极端最高与最低气温转移距离（CTD_Tmax、CTD_Tmin）、年降水量转移距离（CTD_MAP）以及气候水分亏缺转移距离（CTD_CMD）。同时还探究了幼树对移栽样地内气候变量的响应。研究发现，随着CTD的升高，所有受试树种的幼树存活率与生长量均出现小幅下降，这一结果支持了“树种适应的气候（种子来源地的历史气候）与新移栽样地的气候之间的差距越大，幼树表现越差”这一假说。本研究结果显示，年平均气温转移距离（CTD_MAT）与年降水量转移距离（CTD_MAP）的增大将提升幼树死亡风险；而年平均气温转移距离（CTD_MAT）、年极端最高与最低气温转移距离（CTD_Tmax、CTD_Tmin）、年降水量转移距离（CTD_MAP）以及气候水分亏缺转移距离（CTD_CMD）的增大则会导致幼树生长下降。尽管不同树种间存在较高的异质性，但这一整体规律在所有气候变量中均一致显现。