Department of Biology, University of Rwanda, University Avenue, PO Box 117, Huye, Rwanda.
Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 461, Gothenburg, SE-405 30, Sweden.
New Phytol. 2021 Mar;229(5):2548-2561. doi: 10.1111/nph.17038. Epub 2020 Dec 6.
Tropical climates are getting warmer, with pronounced dry periods in large areas. The productivity and climate feedbacks of future tropical forests depend on the ability of trees to acclimate their physiological processes, such as leaf dark respiration (R ), to these new conditions. However, knowledge on this is currently limited due to data scarcity. We studied the impact of growth temperature on R and its dependency on net photosynthesis (A ), leaf nitrogen (N) and phosphorus (P) contents, and leaf mass per unit area (LMA) in 16 early-successional (ES) and late-successional (LS) tropical tree species in multispecies plantations along an elevation gradient (Rwanda TREE project). Moreover, we explored the effect of drought on R in one ES and one LS species. Leaf R at 20°C decreased at warmer sites, regardless if it was expressed per unit leaf area, mass, N or P. This acclimation resulted in an 8% and a 28% decrease in R at prevailing nighttime temperatures in trees at the intermediate and warmest sites, respectively. Moreover, drought reduced R , particularly in the ES species and at the coolest site. Thermal acclimation of R is complete or overcompensatory and independent of changes in leaf nutrients or LMA in African tropical trees.
热带地区的气候正在变暖，大面积地区的干燥期明显变长。未来热带森林的生产力和气候反馈取决于树木使生理过程（如叶片暗呼吸（R））适应这些新条件的能力。然而，由于数据稀缺，目前对此知之甚少。我们在卢旺达树木项目的沿海拔梯度的多物种人工林里，研究了生长温度对 R 的影响及其对净光合作用（A）、叶片氮（N）和磷（P）含量以及单位叶面积的叶片质量（LMA）的依赖性，研究了 16 种早期演替（ES）和晚期演替（LS）热带树种。此外，我们还研究了干旱对一种 ES 和一种 LS 物种 R 的影响。在温暖的地方，20°C 时的叶片 R 无论以单位叶面积、质量、N 或 P 表示，都随温度升高而降低。这种适应导致中间和最温暖地点的树木在盛行的夜间温度下 R 分别降低了 8%和 28%。此外，干旱降低了 R，特别是在 ES 物种和最凉爽的地点。非洲热带树木的 R 热适应是完全的或过度补偿的，与叶片养分或 LMA 的变化无关。
