Trees at the Amazonia-Cerrado transition are approaching high temperature thresholds
Trees at the Amazonia-Cerrado transition are approaching high temperature thresholds
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DOI：
10.1088/1748-9326/abe3b9
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发表时间：
2021-03-01
影响因子：
6.7
通讯作者：
Gloor, Manuel U.
中科院分区：
文献类型：
--
作者：
Araujo, Igor;Marimon, Beatriz S.;Gloor, Manuel U.
陆地地区正在迅速变暖。虽然在一个变暖的世界里，热带以外的纬度地区适应较高温度的植被可能会从低纬度地区移入，但在热带地区这是不可能的。因此，植物功能的限制将决定未来植被的性质和组成。光合作用中对温度最敏感的组分是光系统II。在这里，我们报告的热安全裕度（光系统II耐热性（T-50）和最高叶温之间的差异）在旱季开始的四个树种共同发生在整个森林稀树草原过渡区在巴西，该地区已变暖特别迅速，在最近几十年。所选的物种在森林中万年青，但在稀树草原落叶。我们发现，热带稀树草原上的个体，随着生长温度>40摄氏度，耐热性下降。目前最高叶温超过T-50在一些物种，将超过T-50在2.5摄氏度的世界温暖的大多数物种的评价。尽管叶热特性的可塑性，以增加叶片冷却在较热的环境中，结果表明，这是不足以保持一个安全的热安全裕度在较热的热带稀树草原。总的来说，结果表明，热带森林在未来可能会变得越来越落叶和热带草原。
Land regions are warming rapidly. While in a warming world at extra-tropical latitudes vegetation adapted to higher temperatures may move in from lower latitudes this is not possible in the tropics. Thus, the limits of plant functioning will determine the nature and composition of future vegetation. The most temperature sensitive component of photosynthesis is photosystem II. Here we report the thermal safety margin (difference between photosystem II thermotolerance (T-50) and maximum leaf temperature) during the beginning of the dry season for four tree species co-occurring across the forest-savanna transition zone in Brazil, a region which has warmed particularly rapidly over the recent decades. The species selected are evergreen in forests but deciduous in savannas. We find that thermotolerance declines with growth temperature >40 degrees C for individuals in the savannas. Current maximum leaf temperatures exceed T-50 in some species and will exceed T-50 in a 2.5 degrees C warmer world in most species evaluated. Despite plasticity in leaf thermal traits to increase leaf cooling in hotter environments, the results show this is not sufficient to maintain a safe thermal safety margin in hotter savannas. Overall, the results suggest that tropical forests may become increasingly deciduous and savanna-like in the future.