Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - International Research Training Group 1740


Project C2: Evaluating the atmospheric origins and ecological impacts of drought events in South America using complex networks

Research Team: H. Barbosa (USP), A. Rammig (TUM/PIK), S. Rolinski (PIK), G. Sampaio (INPE)

Outline: Brazil experienced several drought events during the last decade, e.g. the severe droughts in the Amazon basin in 2005 and 2010. Tropical forest ecosystems, particularly in the Amazon basin, serve as an atmospheric moisture pump by taking up water from the soil and re-evaporating moisture, which is in this way transported over long distances. Reduced forest cover from drought mortality in addition to forest loss from deforestation activities may lead to a significant change in atmospheric moisture transport. The objectives of our proposal are therefore to better understand (I) the impacts of drought events on forest ecosystems and (II) the atmospheric mechanisms leading to drought events under current and future global environmental change by applying newly developed complex network measures.

Research Topic: We will study the impacts of drought on forest ecosystems and estimate potential feedbacks to the atmosphere. Decreasing water potential in the plant, e.g. from low soil water supply during drought leads to cavitation which in turn interrupts the water transport through the plant causing damage or mortality of forest trees. Low water supply in leaves also leads to a reduction of transpired water to the atmosphere in turn reducing atmospheric moisture transport. In the proposed project, we will implement a mechanistic treatment of water flow through plants based on the “plant hydraulic architecture” into the dynamic vegetation model LPJmL which is currently being coupled to the atmospheric moisture transport model WAM-2layers . The newly developed model will be used to quantify drought-induced mortality events in different forest types of Brazil and to estimate resulting changes in moisture transport. Potential changes in moisture transport patterns will be analysed by applying newly developed network tools.