Dusenge Mirindi Eric, González-Caro Sebastian, Restrepo Zorayda, Gardner Anna, Meir Patrick, Hartley Iain P, Sitch Stephen, Sanchez Adriana, Villegas Juan Camilo, Mercado Lina M
Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia.
Faculty of Environment, Science, and Economy, University of Exeter, Exeter, UK.
Glob Chang Biol. 2025 May;31(5):e70266. doi: 10.1111/gcb.70266.
Tropical forests play a significant role in global carbon sequestration. However, our understanding of how tropical tree species adjust to climate warming remains limited to studies on seedlings grown in pots and highly controlled growth conditions. To reduce this knowledge gap, we used a field experiment with 5-year-old juvenile trees of 12 naturally co-occurring dominant tropical Andean montane and lowland species growing in three common gardens established along a natural thermosequence in the tropical Andes. Based on a few previous studies, we hypothesized that montane species would exhibit a weaker photosynthetic thermal acclimation capacity compared to lowland counterparts. Our results showed that montane tree species can thermally acclimate net photosynthesis by shifting their thermal optimum (T) by 0.6°C per 1°C of warming. This strong shift in T was correlated to simultaneous strong shifts in T of apparent photosynthetic capacity parameters (V and J), which increased by 0.7°C per 1°C of warming. This strong thermal acclimation resulted in similar rates of net CO assimilation between montane and lowland species across different thermal environments. At last, rates of net photosynthesis at growth temperature explained 30% of the variation in the relative tree growth rates across the two species groups and thermal environments. Our results suggest that the strong physiological acclimation of photosynthesis to warming among montane Andean tree species should be considered when predicting future impacts of warming on Andean plant communities.
热带森林在全球碳固存中发挥着重要作用。然而，我们对热带树种如何适应气候变暖的理解仍局限于对盆栽幼苗以及高度可控生长条件下的研究。为了缩小这一知识差距，我们进行了一项田间试验，选用了12种自然共生的热带安第斯山地和低地优势树种的5年生幼树，这些树种种植在沿着热带安第斯山脉自然温度梯度设置的三个共同花园中。基于之前的一些研究，我们假设山地树种与低地树种相比，其光合热适应能力较弱。我们的研究结果表明，山地树种能够通过每升温1°C将其最适温度（T）偏移0.6°C来对净光合作用进行热适应。T的这种强烈偏移与表观光合能力参数（V和J）的T同时发生的强烈偏移相关，表观光合能力参数每升温1°C增加0.7°C。这种强烈的热适应导致在不同热环境下山地和低地树种之间的净CO同化率相似。最后，生长温度下的净光合速率解释了两个树种组和热环境下相对树木生长速率变化的30%。我们的研究结果表明，在预测变暖对安第斯植物群落的未来影响时，应考虑安第斯山地树种光合作用对变暖的强烈生理适应。
