B52B-08
Ecosystem Function in Amazon Floodplain Wetlands: Climate Variability, Landscape Dynamics and Carbon Biogeochemistry.
Friday, 18 December 2015: 12:05
2008 (Moscone West)
Thiago Sanna Freire Silva1, John M Melack2, Rodrigo Nunes de Sousa1, Jefferson Ferreira-Ferreira3, Annia Susin Streher1, Everton Hafemann Fragal4, Luiz FA Furtado5, Angelica Faria de Resende6, Bruno Garcia Luize1, Conrado Rudorff7,8, Helder L Queiroz3, Jochen Schongart6,9 and Evlyn M Novo5, (1)UNESP Sao Paulo State University, Rio Claro, Brazil, (2)University of California Santa Barbara, Santa Barbara, CA, United States, (3)Mamirauá Sustainable Development Institute, Tefé, Brazil, (4)INPE - National Institute for Space Research, Graduate Program in Remote Sensing, Sao Jose dos Campos, Brazil, (5)INPE - National Institute for Space Research, Remote Sensing Division, Sao Jose dos Campos, Brazil, (6)National Institute for Amazon Research (INPA), Graduate Program in Botany, Manaus, Brazil, (7)INPE National Institute for Space Research, São José dos Campos, Brazil, (8)Centro Nacional de Monitoramento e Alertas de Desastres Naturais, Cachoeira Paulista, Brazil, (9)National Institute for Amazon Research (INPA), Grupo MAUA, Manaus, Brazil
Abstract:
Wetlands comprise 14% of the Amazon basin, and are a major component of the hydrological and biogeochemical cycles. Most of these areas correspond to floodplain ecosystems along the Amazon River and its major tributaries, hosting unique vegetation types that are strongly controlled by annual hydrological fluctuations. The combination of strong environmental filtering and active fluvial dynamics results in a highly heterogeneous landscape, and in physiological linkages between climate variability and ecosystem processes. We will show several years of results obtained within the framework of the LBA program, discussing the interplay between hydroclimatic variability, landscape dynamics, ecosystem functioning and carbon biogeochemistry in the Amazon floodplains. Using optical and microwave remote sensing, we assessed the distribution of major vegetation types and flooding regimes at several locations across the floodplain. Strong variability in vegetation distribution can be observed, with high and low várzea forests ranging from 30% and 34%, respectively, at the upper Solimões River, to 6% and 25% at the lower Solimões, while non-forested habitats and lakes increase from a percent cover of 8% and 10% to 28% and 27%, respectively. Strong variability in local flood regimes was also determined for each vegetation type, revealing a gradient of habitats within each floodplain. As tree growth, diversity and phenology are affected by flood duration, we expect local conditions to strongly impact carbon stocks and cycling at the landscape scale. Fluvial processes also disturb forest patches, ensuring a mixture of age distributions in the landscape, with varying species composition, carbon stocks, and carbon uptake rates. Herbaceous vegetation growth responds very rapidly to changes in hydrological conditions, and modeling based on microwave imagery and in situ observations showed expected changes of up to 50% in annual net primary production between regular and extreme hydrological years. Overall, our results suggest that the combined effect of projected climatic changes and increasing anthropogenic pressures could lead to significant changes in ecosystem dynamics in the floodplain, and landscape heterogeneity needs to be fully accounted for to better forecast impacts on ecosystem processes in the region.
