Effects of drought stress and sward botanical composition on the nutritive value of grassland herbage

The predicted increase of drought incidents even in temperate climates might affect not only yield but the nutritive value of grassland herbage as well. It is not yet clear whether species richness or functional group composition could mitigate a possibly negative reaction of the nutritive value to drought. Here, we report findings of a study investigating the effects of drought stress, species richness (one to five species) and functional group composition (grass, forb and legume) on nutritive value (crude protein, water-soluble carbohydrates, neutral detergent fiber, acid detergent fiber) of herbage under semi-controlled conditions in a vegetation hall. Moderate or strong drought was imposed on plants in one growing season and followed by a recovery period. Drought had no or minor immediate or residual effects on nutritive value, and there was no interaction of species richness or functional group with drought. However, functional group and seasonal variation distinctively influenced the nutritive value of herbage. It was concluded that under conditions of climate change with drought stress events, yield decreases in grassland seem to be by far more important than changes in nutritive value. (C) 2014 Friends Science Publishers