B53J-06
Satellite observations of the role and impacts of dry season climate limitations on tropical forest fates
Friday, 18 December 2015: 14:55
2008 (Moscone West)
Alfredo R Huete1, Natalia Restrepo-Coupe2, Rakhesh Devadas2, Jin Wu3, Kaiyu Guan4, Scott R Saleska3 and Yi Liu5, (1)University of Technology Sydney, Plant Functional Biology and Climate Change, Ultimo, NSW, Australia, (2)University of Technology Sydney, Ultimo, Australia, (3)University of Arizona, Tucson, AZ, United States, (4)Stanford University, Stanford, CA, United States, (5)University of New South Wales, Sydney, NSW, Australia
Abstract:
Climate change scenarios projected for the 21st century predict drying of the Amazon, greening of monsoon tropical Asia and no change in the tropics of Australia. Dry season variability is increasing with complex associated forest responses and feedbacks as they become exposed to longer and/or more intense dry seasons. The functional response of tropical forests to dry seasonal periods is thus crucial to forest resilience, as forests may respond with either enhanced photosynthesis (due to more sunlight) or may dry down with greater susceptibility to fires and release of greenhouse gases and severe public health haze alerts. In this study, we use multiple satellite remote sensing datasets representing forest canopy states, environmental drivers (light and water status), and disturbance (fires), along with
in situ flux tower measures of photosynthesis to assess whole ecosystem patterns and test mechanisms of forest- dry season climate interactions. We compare photosynthesis patterns and dry season responses of Asia-Oceania tropical forests with neotropical forests to better understand forest resilience to climate change and human impacts. In contrast to the neotropics, human activities in monsoon tropical Asia have resulted in intensive transformations of tropical forests. We find forest disturbance exerts a strong influence on tropical forest functioning and a partial loss or degradation of tropical forests can reverse dry seasonal responses with substantial impacts on carbon fluxes. Neotropical forests displayed large variations in dry season forest responses due to spatially variable dry season lengths and magnitude, whereas most of monsoon Asia tropical forests lacked well-defined dry seasons, yet were highly sensitive to shorter term, intense drought events that impacted severely upon the disturbed forests. Our results highlight the interactions among rainfall, radiation and forest health with the relative importance of each factor varying with the characteristics and stages of dry seasonal periods. We find the role of the dry season in sustaining rainforests must be better understood to improve earth system model and future climate predictions.
