OPTIMASS

SPACES Verbundprojekt OPTIMASS: Optionen für nachhaltiges Geo-Biosphären-Rückkopplungs-Management in Savannen. Teilprojekt 3: Pflanzenanghängige biochemische Steuergrößen

01/12/2014 to 30/11/2017

Shrub encroachment, i.e. the expansion of woody vegetation at the expense of herbaceous plants, has become a major threat to the functioning of African savannas. Their use as rangelands is also endangered, and it has been hypothesized that this problem could be aggravated under climate change. In addition, elevated CO2 is particularly interesting because of the different photosynthetic pathway of the two main plant life forms: one of which (shrubs) is predicted to suffer more from drought but at the same time profit more from elevated CO2 than grasses- the main food for wildlife and livestock. We take a nested approach to study the combined impact of elevated temperatures, reduced rainfall, and elevated CO2 on the interactions between grasses and shrubs in Namibian savannas. On a large scale, we use reciprocal transplants of seeds for estimating the impact of climate on shrub-grass interactions. Within selected sites, we actively impose artificial drought. On the smallest scale, we use greenhouse and climate chamber experiments (at the University of Hohenheim, A. Fangmeier’s lab) to test for the combined effects of water availability, CO2 concentration, nutrients and herbivory on the balance between grasses and shrubs at a seeding stage. The overall findings will help us identifying means of managing grazing in a manner adapted to future climate change.

This project is part of OPTIMASS- a larger consortium of scientists from Germany and Namibia, which is coordinated by the University of Potsdam.