PS 43-157 - CANCELLED - Regenerative strategies of Euterpe edulis (Arecaceae) at its altitudinal limits in the Atlantic Forest

Abstract: Populations occurring at the boundary of the species’ altitudinal distribution undergo strong environmental filtering, especially in the face of rapid climate change. This can have significant effects on the survival and growth of plant populations, making it essential to understand their ecological responses in the early stages of development. However, few studies have explored the strategies that plant populations use to establish themselves at the edge of their distribution in response to global warming. To address this knowledge gap, we conducted experiments to investigate the effects of increasing temperatures on the germination and seedling establishment of two populations of Euterpe edulis, a palm tree species vulnerable to extinction. The Montana Forest population grows at 1200 meters above sea level in the Montane Dense Ombrophylous Forest of the Serra dos Órgãos National Park, while the Restinga population is found in the Coastal Plain Forest at sea level in the Restinga de Jurubatiba National Park, Brazil. The tests were conducted in the laboratory for 90 days, where the seeds were exposed to three conditions simulating heat waves: control at 25°C and two treatments at higher temperatures (35°C and 40°C). Seeds were exposed to the treatments for seven days and after that period they returned to control temperatures. We measured the seed germination rate, mortality rate, average germination time, and shoot and root biomass. Our results showed that the germination rate was not affected by the population, seed size class, or temperature treatments. However, average germination time and mortality increased in the Montana Forest population under the most extreme treatment, while in the Restinga population, they were affected by a small increase in temperature. Additionally, we found that small seeds invested more in shoot than root biomasses in the Restinga population, while larger seeds invested more in shoot and root. The investment of small seeds in the shoot can be a strategy to escape the thick litter and increase the capture of light energy. However, these seedlings are more vulnerable to disturbance than the Montana Forest seedlings, as the temperature affected more strongly their metabolism. We conclude that populations at the lower altitudinal limit are closer to the thermal limit of the species and are more vulnerable to temperature increases than populations at the upper limit of the species' altitude range. Understanding the effects of climate change on plant populations is critical for predicting their vulnerability to extinction and developing effective conservation strategies.