PARENT SESSION
Monday, August 7, 5:00-6:30 pm
Poster Session 7 - Climate and global change
Exhibit Hall, Ballroom Level, Cook Convention Center

The importance of positive interactions in a high-alpine environment under global warming.

Molina-Montenegro, Marco^{*,1, 2}, Cavieres, Lohengrin^{1, 2}, ¹ ECOBIOSIS, Departamento de Botánica, Universidad de Concepción, Concepción, Chile² Instituto de Ecología y Biodiversidad, Santiago, Chile

ABSTRACT- In the last centuries some changes in the general climatic conditions of the planet has been observed, phenomenon known as "climate global change". One of the climatic changes most studied and documented is the global warming, the increase in the global temperature of the planet. High-elevation environments are one of the habitat most sensitive to the effects of global warming. In these stressful habitats, positive interactions are expected to be the most important interspecific interaction, particularly facilitation by nurse species that ameliorate the stressful environmental conditions (e.g., low temperatures), increasing the survival of some species. We hypothesized that under a global worming scenario, facilitative interactions should decrease in importance. During two growing seasons we assessed the importance of a nurse species on the photosynthetic performance of two beneficiary species at 3600 m elevation in the Andes of central Chile. Five individuals of both beneficiary species were exposed to 4 treatments each: (1) nurse removal, (2) nurse removal + global warming simulation, (3) nurse presence + global warming simulation, and (4) a control with the presence of the nurse. Global warming was simulated with open-top chambers (OTC) following the ITEX protocol. Fluorescence parameters of chlorophyll (Fv/ Fm, PS II, ETR, qP and NPQ) were measured on each experimental individual. Nurse removal decreased photosynthetic performance compared to control, indicating the importance of the facilitative interaction. However, the photosynthetic performance of individuals where the nurse was removed under a global warming simulation did not differ from that on control plants. Interestingly, individuals under a global warming simulation with the presence of the nurse showed a higher photosynthetic performance than the control plants. Our results suggest that positive interaction does not decrease in importance under a global warming scenario. FONDECYT 1060710 and P02-051-F ICM.

Key words: Global warming, Alpine environments, Positive interactions