Root water uptake in grasslands with different management

Grasslands are highly dynamic ecosystems which adapt to environmental factors such as climate, soil characteristics and anthropogenic management. Yet, the belowground reaction and adaptation of grassland communities to aboveground drivers are poorly understood. Therefore, we investigated differences in the temporal dynamics of root water uptake, its depth pattern and the evolution of plant available soil water storage between grassland of three distinct management types. Root water uptake in 6 depths up to 90 cm was estimated from diurnal fluctuations of soil water content during rain free periods. Soil moisture measurements were conducted on three replicates of (i) extensively and (ii) intensively managed grassland plots as well as (iii) extensive pasture plots at the Global Change Experimental Facility (GCEF) in Bad Lauchstädt (Central Germany). We found that the grassland vegetation takes up water in depths up to 70 cm during the vegetation period. But while reaching deeper, the total amount of extracted water decreased. The main water source at the beginning of the growing season and after each mowing was in the top 20 cm. However, after mowing, still some uptake in greater depths can be observed. Interestingly, the pastures showed the shallowest uptake profiles although they are not mown and despite their high biodiversity. Our results confirm that water uptake by growing grassland vegetation shifts to deeper soil layers when compensating for the accumulated atmospheric water deficit.