No improvement of plant biodiversity in ditch banks after a decade of agri-environment schemes

Published source details Blomqvist M.M., Tamis W.L.M. & de Snoo G.R. (2009) No improvement of plant biodiversity in ditch banks after a decade of agri-environment schemes. Basic and Applied Ecology, 10, 368-378.
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This study is summarised as evidence for the following.

	Action	Category
	Manage ditches to benefit wildlife Action Link

Manage ditches to benefit wildlife

A replicated site comparison (paired) study of ditch banks on six dairy farms in the western peat district of the Netherlands (Blomqvist et al. 2009) found that agri-environment scheme ditch management did not result in increased plant diversity or decreased productivity over 10 years. The total number of plant species on ditch banks under agri-environment scheme management decreased significantly between the periods 1993-1995 (31 species) and 2000-2003 (29 species); numbers of target plant species did not differ (7 species). Productivity on agri-environment scheme ditch banks measured as grass/broadleaved plant ratio increased significantly (1993-1995: 0.37; 2000–2003: 0.44) and Ellenberg nitrogen values increased in four and decreased in two farms (1993-1995: 5.82; 2000-2003: 5.92). Differences between agri-environment scheme and surrounding ditch banks tended to decrease over the study period. Plant diversity data were obtained from agri-environment scheme ditch banks in July-August 1993-1995 and May 2000-2003 (42 repeatedly sampled plots) and non-agri-environment scheme ditch banks surrounding five of the farms (78 plots/year). Five replicate biomass samples were taken from agri-environment scheme ditch banks in mid-May 2000-2002 (9-72 plots) before grazing and mowing. Two productivity measures were also derived from botanical data: grass/broadleaved plant ratios and Ellenberg nitrogen-values.