Identification of functional groups in páramo plants and evaluation of their susceptibility to global climate change

• Autores: Marisol Cruz Aguilar
• Directores de la Tesis: Eloisa Lasso (dir. tes.)
• Lectura: En la Universidad de los Andes (Colombia) ( Colombia ) en 2022
• Idioma: inglés
• Tribunal Calificador de la Tesis: Peter Reich (presid.), Catalina González Arango (presid.)
• Enlaces
  • Tesis en acceso abierto en: hdl.handle.net
• Resumen

  • Above treeline in the mountains from the Northern Andes, there is an ecosystem of restricted distribution locally called as páramo. Páramos are tropical ecosystems of high altitude where there are special conditions that make them and their flora unique, such as greatly dynamic cloud conditions, excessive amounts of UV radiation, rapid changes of incident sunlight and pronounced temperature fluctuations during each day, among others. They are critical as a source of water in the region, are important carbon sinks, are home to a vast endemic flora, and possess some of the fastest rates of diversification in the world. Although the ecosystemic services of páramos depend to their high spatial abiotic and biotic heterogeneity that generates complex mosaics of plants associations; unfortunately, little work has been done on the susceptibility of páramo plants to climate change. Human-induced climate change is affecting all the Earth's biomes, including páramos, where models predict that temperatures will increase, while the volume and frequency of precipitation will decrease to the end of this century. All research indicates that warmer and drier environments will drive vegetation upward, as plants did in the past, during interglacial periods, rather than adapting to the new conditions. Plants can respond to climate change by adaptation, migration, or local extinction; adaptation implies that plants can acclimate its physiology to the new conditions, migration requires reproductive traits that favored dispersal and colonization of new areas, and it is well established, that species with limited ranges of distribution, such as those restricted to the páramo, have a higher risk of extinction. However, adaptation and migration capacities are not enough studied facing global warming in plants of the humid Colombian páramo. In the first chapter, new findings in plant functional classification are presented that allow us to conclude that although the harsh conditions of páramos promote a huge variety of morphological adaptations, it is also the cause of a smaller number of functional responses, and since functional responses are closely linked to growth forms, in páramos it could be useful to use growth forms as a proxy of plant functional types (PFT) in all cases and with caution in the case of shrubs. In the second chapter, thermal acclimation of photosynthesis and respiration was evaluated and, in addition to the limited functional response, it was found that páramo plants have a limited capacity for thermal acclimation, but although páramo plants cannot adjust their physiology to warming, high temperatures do not have an adverse effect on plant performance. Finally, in the third chapter, the effect of warmer temperatures on germination traits was evaluated and it was found that seeds of few páramos plants will be affected by higher temperatures, so it appears that there is a wide range of temperature functioning for germination processes. All results together seem indicate that although páramo plants are more capable of migrating than adapting, they would survive because other mechanisms as decoupling leaf temperature from ambient temperature may operate ensuring their survival.