Substitutes for grazing in semi-natural grasslands - do mowing or mulching represent valuable alternatives to maintain vegetation structure?

Published source details Römermann C., Bernhardt-Römermann M., Kleyer M. & Poschlod P. (2009) Substitutes for grazing in semi-natural grasslands - do mowing or mulching represent valuable alternatives to maintain vegetation structure?. Journal of Vegetation Science, 1086-1098.
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Summary

Ancient semi-natural grasslands in Europe are very valuable for nature conservation due to the high floristic and faunistic diversity that they support. Such grasslands, traditionally livestock grazed for centuries, have been increasingly abandoned or management has changed as grazing is no longer economically viable. A study was undertaken on species-rich calcareous grassland in St. Johann in the Swabian Alb Mountains of Baden-Württemberg (southwest Germany) to assess the suitability of different mowing regimes as an alternative to grazing to maintain these grasslands.

Until 1974, the grassland was sheep grazed at low intensity, after which 'mulching' (i.e. mowing without removal of cut material) regimes were introduced: mulching once per year (in late summer), twice per year (early and late summer) or every second year (in late summer). One part of the site continued to be grazed, and another site was unmanaged.

Mowing (i.e. cut material removed) was introduced in 1981 at an abandoned site.

In 1974, a permanent (5 x 5 m) quadrat was established at each site within each treatment area. Percentage vegetation cover was monitored every 3-5 years to 2004. Changes in floristic and functional composition were analysed.

In the grazed area vegetation was in functional and floristic equilibrium. All alternative management treatments led to vegetation changes. Mulching twice per year and mowing where best at maintaining floristic composition and structure in a (desired) state most similar to that of the grazed area.

The authors consider that the alternative management treatments tested are not appropriate to sustain the typical disturbance dynamics of these grasslands. They suggest that if grazing cannot be maintained on species-rich semi-natural grasslands, cutting at least twice per year is required.

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