M. Kayser

Phytodiversity of temperate permanent grasslands: ecosystem services for agriculture and livestock management for diversity conservation

Plant diversity has been reported to increase productivity. Farming practices aiming at conserving or increasing plant diversity are, however, usually less profitable than conventional ones. In this review, we aim to find reasons for this discrepancy, discuss ecosystem services of grassland phytodiversity that are useful for farmers, and ways of livestock management most beneficial for diversity. Under agricultural conditions, a clear effect of species richness on a site’s primary or secondary production has not yet been demonstrated. Reasons could be that species numbers in permanent grassland are above the threshold of five species found effective in experimental plots or that the conditions are more in equilibrium with management than in weeded experimental plots. Other diversity effects on production stability, nutrient and water retention or product quality might convince farmers to increase diversity. However, these should be tested in agricultural situations, as most research has again been carried out in experimental plots. To enhance phytodiversity, grazing has been found superior over mowing, as selective grazing, treading and excreta deposition increase the heterogeneity of a sward and thus the niches available. Especially rotational grazing with intermediate intensity may be advantageous for phytodiversity. However, complex interactions between environmental conditions, sward composition, management and livestock behaviour make it difficult to forecast grazing effects. Thus, ecological and agricultural researchers should cooperate more, e.g. either in interdisciplinary projects or by hiring researchers from the respective other profession and thus diversifying research groups, in order to integrate agricultural management into biodiversity research and biodiversity measurements into agricultural research to advance our understanding of how to make conservation and enhancement of grassland phytodiversity both feasible and sustainable.

Using 13C in cattle hair to trace back the maize level in the feeding regime—A field test

Sections from cattle hair serve as an isotopic archive—they contain information on the cattle diet from different time periods. We tested the reliability of 13C signatures (δ13C) in cattle tail switch hair to retrospectively trace back the annual dietary proportion of maize of different production systems without having to sample and analyze the feed. Furthermore, we investigated if differences in dietary proportion of maize during summer and winter feeding can be detected in a single tail switch hair by sampling hair only once a year. We sampled hair and obtained information on management and annual composition of diets on 23 cattle farms in northern Germany. Farms differed in dietary proportions of maize, grass and concentrates as well as in grazing regime (year-round grazing, summer grazing, no grazing). We found that the annual mean δ13C values (δ13CY) of two hair sections that contain the isotopic information of summer and winter feeding is a robust indicator for the annual proportion of maize in cattle diet on a farm. The grazing regimes could clearly be distinguished by analyzing seasonal mean δ13C values (δ13CS). We could also demonstrate short term changes in the diet changes by means of δ13CS. We conclude that the method can be used in different cattle production systems to check on dietary proportions of maize for a period of one year before sampling of hair.