Water and carbon fluxes along a land use gradient in the tropical mountain dry forest of South Ecuador

Ecosystems play an important role in controlling the exchange of energy, water and carbon between the land surface and the atmosphere, which contributes to the regulation of the climate through biogeochemical process. Changes in vegetation or biomass impacts the microclimatological conditions of the landscapes with feedbacks to the heat and water budgets. Knowledge about the dynamics and driving factors of the exchange processes contributes to our understanding of the land surface – atmosphere interactions as drivers of the Earth’s surface energy budget.

In the Tumbesian mountain dry forest (MDF) in the Laipuna reserve on the western escarpment of the Andes mountains in South Ecuador two eddy-covariance measurement stations have been installed over natural forest and an anthropogenic replacement system to observe atmospheric water and carbon fluxes. The MDF is characterized by a distinct seasonality, which can be divided into a dry (May - December) and wet (November - May) season following the inter-hemispherical shift of the ITCZ. Mean monthly precipitation totals ranges between 50 and 400mm with an annual amount of 650mm, while the temperature varies between 21 – 26°C. The forest ecosystem is dominated by deciduous trees and hold a clear annual cycle in the water budget and carbon sequestration. In the scope of global climate change such water limited landscapes are strongly vulnerable to climatic stress situations which lead to changes in the phenological cycles in the ecosystem associated with feedbacks to the water and carbon cycle. The aim is thus, to investigate the energy, water and carbon dynamics along a land use gradient in order to estimate the impact of deforestation on net-ecosystem exchange and evapotranspiration in the MDF region. The study shows first results of microclimatological conditions, such as radiative fluxes, moisture and soil conditions of both sites as well as water and carbon fluxes.