Responses of Andean Montane Forests to Climate Change

热带安第斯森林拥有地球上最高的植物生物多样性。目前全球变暖的速度是南美其他地区的三倍。因此，气候变化和低地物种的入侵迁徙对未来山地森林的多样性和功能构成了重大挑战。因此，热带安第斯山脉是研究热带树木光合作用适应温度变化的潜力的高度优先地区。现在有证据表明，一些高海拔树种的温暖边缘范围缩小，表明对最近的变暖做出了强烈反应。因此，为了大大提高对未来热带安第斯森林生产力变化的预测，并评估对生物多样性的影响，确定物种范围的变化是否与生理适应高温的能力有关是至关重要的。该项目是设在哥伦比亚的一个现有的、令人兴奋的NERC项目的一部分，旨在全面了解关键气体交换过程的热适应和安第斯山脉森林的生长。该博士项目的目的是确定安第斯森林物种光合作用和呼吸的热适应程度。将测试的关键假设是：-山地热带森林物种的热适应程度将低于在温带和高纬度生态系统中观察到的程度。-山地物种的适应潜力将与这些物种可以生长的温度范围呈正相关。该项目将使用三个沿着哥伦比亚安第斯山脉海拔梯度建立的常见花园实验。具体地说，我们正在种植1200棵树(3个地点各400棵，图1-图2)，覆盖了哥伦比亚安第斯山脉最主要的山地森林物种的60%。成功的候选人将使用便携式光合作用系统，在种植12-18个月后从选定的物种中测量三个地点的光合作用和呼吸作用的叶水平，以量化山地森林物种是否能够适应高温以及适应的程度。

Tropical Andean forests host the highest plant biodiversity on Earth. Current rates of warming are three times higher than elsewhere in S. America. Therefore, climate change together with invasive migration by lowland species pose significant challenges to the diversity and functioning of montane forest in the future. Hence, the tropical Andes is a high-priority area in which to study the potential for tropical trees to acclimate their photosynthesis to changes in temperature.There is now evidence for warm-edge range contraction in some high elevation tree species, suggesting a strong response to recent warming. Thus, to substantially advance predictions of how the productivity of tropical Andean forests will change in the future, as well as to assess impacts on biodiversity, it is essential to determine whether changes in species ranges are associated with abilities to physiologically acclimate to higher temperatures.This project is part of an existing and exciting NERC funded project based in Colombia with aim to deliver a comprehensive understanding of thermal acclimation of key gas exchange processes and growth in montane Andean forest.The aim of this PhD project is to determine the degree of thermal acclimation of photosynthesis, respiration of Andean forest species. The key hypotheses that will be tested are: -The extent of thermal acclimation of montane tropical forest species will be less than that observed in temperate and high-latitude ecosystems.-Acclimation potentials of species in montane zones will be positively related to the range of temperatures the species can grow under.The project will use three common garden experiments established along an elevation gradient in the Colombian Andes. Specifically, we are planting 1200 trees (400 at each of 3 sites, Fig1-Fig2) covering 60% of the most dominant montane forest species in the Colombian Andes. The successful candidate will use a portable photosynthesis system to take leaf level measurements of photosynthesis and respiration at the three sites from a selection of species after 12-18 months of planting in order to quantify whether juvenile montane forest species can acclimate to high temperatures and to what extent.