Effect of 15‐year sward management on vertical distribution of plant functional groups in a semi‐natural perennial grassland of central Europe

Abstract

Aims: The nutrient concentration in herbage and biomass productivity analyses are dependent on the vertical distribution of different sward layers where the sampling is done. Notably, a majority of studies indicate clipping biomass to the ground level without any consideration of the vertical distribution. This study examined the effect of cutting and grazing intensities on the vertical distribution of plant functional groups. Location: Oldřichov Grazing Experiment, northern Czechia. Methods: During a 15-year experiment: (a) intensive and (b) extensive grazing without cutting; (c) cutting in June followed by intensive and (d) extensive grazing; and (e) undefoliated treatment were applied throughout the vegetation season. Biomass data were collected at two layers in the sward (below and above 3 cm) and separated into five functional groups. Biomass data were analysed to examine the succession and effects of treatments on vertical distribution of functional groups. Results: Treatment effects were differentiated after 2-3 years from the introduction of management, but the composition of functional groups fluctuated over time. Treatments significantly affected total biomass of all functional groups and the vertical distribution within swards of most groups. Particularly intensive grazing significantly decreased the total biomass of graminoids, forbs, and dead biomass in favour of legumes (which increased). This led to a shift in the relative biomass distribution from the upper sward layer to the lower layer for most functional groups except for legumes and mosses. Conclusion: The high proportion of dead biomass in the lower sward layer suggests the need for a methodological approach that considers clipping of biomass only above 3 cm when sampling for productivity and forage quality analysis. This approach would avoid including biomass from below 3 cm or the lower layer, which would be ungrazed by cattle. Many previous studies may have reported a distorted or inflated value in herbage productivity or forage quality results.

The effect of 19 years of restoration managements on forage quality and herbage‐soil relationships within improved upland grassland

“…The sheep grazing not only reduced the cover of forbs in our experiment (Pavlu ˚et al, 2021) 60% of the sward under intensive and extensive grazing respectively (Kassahun et al, 2021). The rejected vegetation resulted in the estimated forage quality based on IVOMD and NDF being lower (Table 3) for vegetation within grazed only treatments compared to treatments which included cutting (hay and hay/grazed treatments), where almost all biomass was removed annually, rejuvenating the sward.…”

“…Moreover, the forage quality was negatively affected by the sampling method, as biomass was cut at the ground level with a stubble height of less than 1 cm. This type of sampling includes low quality dead biomass, which may account for 25% to over 60% of the sward under intensive and extensive grazing respectively (Kassahun et al, 2021). The rejected vegetation resulted in the estimated forage quality based on IVOMD and NDF being lower (Table 3) for vegetation within grazed only treatments compared to treatments which included cutting (hay and hay/grazed treatments), where almost all biomass was removed annually, rejuvenating the sward.…”