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Higher temperatures increase growth rates of Rocky Mountain montane tree seedlings
Ecosphere ( IF 2.7 ) Pub Date : 2021-03-21 , DOI: 10.1002/ecs2.3414
Charles J.W. Carroll 1 , Alan K. Knapp 1 , Patrick H. Martin 2
Affiliation  

Recent observational studies report weak or flat temperature − growth relationships for many tree species in temperate forests. In contrast, distribution limits of trees are strongly shaped by temperature, and studies show marked short‐term temperature effects on leaf‐level ecophysiology. To better determine the effects of warming on trees, we planted one‐year‐old seedlings of one lower montane (ponderosa pine), two upper montane (quaking aspen and lodgepole pine), and one subalpine tree species (subalpine fir) in in situ experimental gardens on an elevation gradient in the Rocky Mountains (USA) which span a 6°C range in temperature but have approximately uniform precipitation. Seedlings were lightly watered the first three growing seasons to facilitate establishment, and growth and survivorship were followed for four years. We expected a trade‐off between growth and survivorship, as seedlings in high temperatures grow faster (e.g., with a longer growing season), but have higher mortality from heat stress. Compared to the coldest site, aspen (+256% wider, +337% taller), ponderosa pine (+234% wider, 270% taller), and lodgepole pine (+235% wider, 283% taller) all had strikingly higher cumulative diameter and height growth in the warmest site by the end of the study. Linear models of cumulative and annual growth in the montane species showed strong, positive relationships with growing‐season temperature, but no significant relationships with growing‐season precipitation. In contrast, growth of subalpine fir did not vary significantly with temperature, but increased slightly with higher growing‐season precipitation. Accelerated growth did not come at the expense of survivorship in the montane species: cumulative four‐year survivorship of the montane species remained robust (71.4–94.4%) in high temperatures, but caused complete mortality of subalpine fir. As long as precipitation remains adequate, these results indicate that warming is likely to strongly increase growth in seedlings of montane species with only modest decreases in survivorship despite higher evapotranspiration, especially in cooler and wetter portions of their current distributions where hydric stress is low. In contrast, warming may negatively affect seedling growth and survival in hotter and drier areas of the Rockies, and warming of +3–6°C may endanger the persistence of subalpine fir over much of its current distribution.

中文翻译:

较高的温度提高了落基山山地树木幼苗的生长速率

最近的观测研究报告说,温带森林中许多树种的温度-生长关系较弱或平坦。相比之下,树木的分布极限受温度的强烈影响,研究表明短期温度对叶级生态生理的影响。为了更好地确定气候变暖对树木的影响,我们在原地种植了一年生的一种低山(ponderosa松),两种高山mont(白杨和黑毛松)和一种亚高山树种(亚高山杉)的幼苗。落基山脉(美国)海拔梯度为6°C的实验性花园,但降水量大致均匀。在开始的三个生长季节中,给幼苗轻浇水以利于定植,并在随后的四年中对其生长和存活进行跟踪。我们预计生长和生存之间需要权衡,因为高温下的幼苗生长更快(例如,生长季节更长),但是由于热胁迫而导致的死亡率更高。与最冷的地点相比,白杨(宽+ 256%,高+ 337%),黄松(宽+ 234%,高270%)和黑毛松(宽+ 235%,高283%)的累积量都惊人地高。到研究结束时,最温暖的地点的直径和高度增长。山地物种累积和年增长的线性模型显示出与生长季节温度的强正相关,但与生长季节降水无显着关系。相反,亚高山冷杉的生长并没有随温度显着变化,但随着生长季节降水的增加而略有增加。加速生长并不以牺牲山地物种的生存为代价:在高温下,山地物种的累积四年生存率仍保持强劲(71.4%至94.4%),但造成了亚高山冷杉的完全死亡。只要降水量保持足够,这些结果就表明,尽管蒸散量更高,但变暖的山地树种幼苗的生长可能会大大增强,而存活率仅略有下降,特别是在水分分布较低的当前分布较凉和较湿的部分。相反,变暖可能会对落基山脉较热和较干燥的地区的幼苗生长和生存造成负面影响,而+ 3–6°C的变暖可能会危害大部分当前分布的亚高山冷杉的持久性。在高温下,山地物种的累计四年生存率仍然很高(71.4–94.4%),但导致了亚高山冷杉的完全死亡。只要降水量保持足够,这些结果就表明,尽管蒸散量更高,但变暖的山地树种幼苗的生长可能会大大增强,而存活率仅略有下降,特别是在水分分布较低的当前分布较凉和较湿的部分。相反,变暖可能会对落基山脉较热和较干燥的地区的幼苗生长和生存造成负面影响,而+ 3–6°C的变暖可能会危害大部分当前分布的亚高山冷杉的持久性。在高温下,山地物种的累计四年生存率仍然很高(71.4–94.4%),但导致了亚高山冷杉的完全死亡。只要降水量保持足够,这些结果就表明,尽管蒸散量更高,但变暖的山地树种幼苗的生长可能会大大增强,而存活率仅略有下降,特别是在水分分布较低的当前分布较凉和较湿的部分。相反,变暖可能会对落基山脉较热和较干燥的地区的幼苗生长和生存造成负面影响,而+ 3–6°C的变暖可能会危害大部分当前分布的亚高山冷杉的持久性。只要降水量保持足够,这些结果就表明,尽管蒸散量更高,但变暖的山地树种幼苗的生长可能会大大增强,而存活率仅略有下降,特别是在水分分布较低的当前分布较凉和较湿的部分。相反,变暖可能会对落基山脉较热和较干燥的地区的幼苗生长和生存造成负面影响,而+ 3–6°C的变暖可能会危害大部分当前分布的亚高山冷杉的持久性。只要降水量保持足够,这些结果就表明,尽管蒸散量更高,但变暖的山地树种幼苗的生长可能会大大增强,而存活率仅略有下降,特别是在水分分布较低的当前分布较凉和较湿的部分。相反,变暖可能会对落基山脉较热和较干燥的地区的幼苗生长和生存造成负面影响,而+ 3–6°C的变暖可能会危害大部分当前分布的亚高山冷杉的持久性。
更新日期:2021-03-22
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