Regional-scale ecohydrological consequences of widespread forest cover in northern South-America: Amazon forest effects on atmospheric and surface water balances

Abstract:

Vegetation plays a key role on the distribution and regulation of the water budget in multiple spatial and temporal scales. These regulation properties occur as a consequence of vegetation-mediated ecohydrological processes that result in the modification of hydrological fluxes that define water budgets in basins, ranging in size from squared meters to millions of squared kilometers. Important empirical and theoretical advances in the field of Ecohydrology have developed a robust theoretical framework to explain these interactions, particularly at local to regional scales. However, recent hypotheses have suggested that the presence of widespread-continuous forests, such as those occurring in tropical South America, plays a more active role in the regional climate, and particularly in the transport of atmospheric moisture from the ocean, eventually becoming precipitation over the continental masses. This condition, associated with the regulating role of natural vegetation on surface water balance and ecohydrological processes, produces ecohydrological and ecoclimatological effects that have important regional and potentially global implications. In this work we present preliminary observations on the relationship between the presence of widespread continouos forests in tropical South-America and the characteristics of precipitation regimes along atmospheric moisture transport pathways, through the combined use of multiple hydroclimatological and vegetation cover datasets. Further, we develop a corresponding analysis of the relationship between the forest cover and streamflow dynamics in tropical basins, using the scaling theory framework. Our preliminary observations highlight a distinguishable differentiation in precipitation regimes in atmospheric moisture pathways in forested vs. non-forested areas. Additionally, the regulating effect of tropical forests is also highlighted by differences in rainfall-runoff relationships and hydrological scaling properties of basins with different amounts of natural forest cover. Overall, our preliminary results highlight a large-scale effect of forest cover in ecoclimatological processes that determine key ecohydrological properties of tropical ecosystems.