Data for: Grazing effects of wintering geese on grassland yield: A long-term study from NW-Germany

Conflicts between grassland farming and wintering geese stimulated a long-term study on goose-dependent yield losses. In the period 1996-2018 the loss of dry biomass of the first harvest increased from ca. 15 % to 50 % which corresponds with changes in the number and migratory behaviour of the barnacle goose. In contrast we found no decline in grassland yields with increasing number of greater white-fronted geese. The second harvest was not affected by wintering geese. The present study forms the basis for a fair and comprehensible system of compensation payments fo affected farmers.

Methods
The effects of goose grazing were mesured by comparing dry biomass yields of the first and second harvest in grazed and ungrazed plots of the same size in fields distributed over the whole study site. Apart from the dry biomass we compared the quality of the harvest of both plot types, particularly the contents of energy, crude protein, crude fiber and ash. We weekly monitored the densities of barnacle and greater white-fronted geese as well as the combined number of all geese during the whole wintering period across an area of 100 ha around the investigated plots.