PS 15-1 - Increased intra-annual precipitation variability affect biomass production and forage quality

Tuesday, August 9, 2011
Exhibit Hall 3, Austin Convention Center
Kerstin Grant1, Juergen Kreyling2, Laura F. H. Dienstbach2, Carl Beierkuhnlein2 and Anke Jentsch3, (1)Disturbance Ecology, University of Bayreuth, Bayreuth, Germany, (2)Biogeography, University of Bayreuth, Bayreuth, Germany, (3)Disturbance Ecology, University of Bayreuth, Germany

Greater intra-annual precipitation variability is predicted for many regions on earth, leading to longer dry periods and more intense rainfall events. Recent studies suggest that changed precipitation variability is altering grassland productivity but it remains unclear how forage quality is affected. Here, we present results from the field experiment EVENT II in which an extensively used Central European grassland was subjected to increased rainfall variability (low, mid and extreme rainfall variability without any change to the annual rainfall amount). We further asked if the application of fertilizer (NPK) and the delay of mowing are useful management options to buffer against loss of forage quantity and quality. Rainfall variability, fertilization and mowing were fully crossed and each factorial combination was replicated five times. We assessed biomass production and forage quality parameters such as crude protein, crude ash, crude fat and fibre, sugar content as well as neutral detergent fibre (NDF).


Biomass production, NDF, crude fibre and sugar content decreased with increasing precipitation variability. Fertilizer application did not affect the response to increased variability. Delayed mowing buffered against the reduction of crude protein with increased variability, while biomass production was not affected. When extreme drought periods occurred later in the year, crude protein, sugar and biomass decreased even stronger while crude fibre and fat increased. These results may contribute to the discussion on adaptation against climate change in extensively used grasslands which are of high value both to agriculture and nature conservation.

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