Seminar: Laura Nadolski

Semi-arid ecosystems strongly impact the variability of the global terrestrial carbon sink and are influenced by a changing climate as well as anthropogenic nitrogen deposition. To understand how different nutrient availability impacts the drivers of net ecosystem exchange (NEE) in these ecosystems across temporal scales, we analyze a long-term dataset of biometeorological, soil and flux data from 2016 to 2022 from three Eddy Covariance (EC) measurement stations in Western Spain. The site (Majadas de Tiétar) is a Mediterranean tree-grass ecosystem home to a large-scale fertilization experiment. One station area received nitrogen (N) treatment, another one both nitrogen (N) and phosphorus (P) treatments, and the third one serves as control.

Preliminary findings show an increase in NEE dynamics in the fertilized areas. On the daily scale, NEE is closely coupled to radiation, whereas on the seasonal scale water availability gains importance in predicting NEE. While on the daily scale the differences between the three fertilization treatments are marginal, they intensify at the seasonal scale. We further find that fertilization shortens the reaction time of NEE to changing environmental drivers.