Community Seasonal Development Enables Late Defoliation Without Loss of Forage Quality in Semi-natural Grasslands

Abstract

Agri-environmental measures often require postponing of grassland defoliation until summer months. We investigated how this affects agronomic characteristics, i.e., biomass production and forage quality, in species-rich grasslands in the White Carpathian Mountains, Czech Republic. Three distinct grasslands (vegetation alliances Bromion erecti, Cynosurion cristati, Violion caninae) were selected for biomass sampling in three dates: mid-May, early June and end of June. Proportions of individual species from total biomass, biomass production, crude fibre concentration, organic matter digestibility and community functional properties (forage value, leaf dry matter content, specific leaf area) were determined. Dry matter standing biomass at the end of June was highest in Bromion with 3.5 t/ha, followed by Violion with 2.7 t/ha and Cynosurion with 2.3 t/ha. A steep decline in forage quality (increase in crude fibre and decrease in organic matter digestibility) during accumulation of above-ground biomass was recorded in formerly unmanaged Bromion grassland but remarkably not in formerly grazed Cynosurion and Violion grasslands where early spring dominants were partly replaced by later developing species, Agrostis capillaris and Trifolium spp. Abundance-weighted community functional properties were consistent with results obtained from biomass chemical analyses, thus the ‘trait approach’ can be used as a suitable surrogate of costly and labor-intensive laboratory procedures. Finally, we assume that the high degree of community seasonal development in Cynosurion and Violion, indicated here by a new community seasonal development index and by development in community specific leaf area, was accountable for the stabilization of forage quality later in the vegetation season.