Agri-environment schemes do not effectively protect biodiversity in Dutch agricultural landscapes

Published source details Kleijn D., Berendse F., Smit R. & Gilissen N. (2001) Agri-environment schemes do not effectively protect biodiversity in Dutch agricultural landscapes. Nature, 413, 723-725.
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This study is summarised as evidence for the following.

	Action	Category
	Introduce agri-environment schemes to benefit wild bees Action Link
	Reduce management intensity on permanent grasslands for birds Action Link
	Reduce management intensity on permanent grasslands (several interventions at once) Action Link

Introduce agri-environment schemes to benefit wild bees

In a replicated trial with 39 pairs of fields, Kleijn et al. (2001) found meadow bird agreements and/or botanical agreements, aimed at conserving wading birds and species-rich vegetation, respectively, in the Netherlands, enhanced the number of bee species relative to conventionally managed control fields. Bee diversity was very low in this study, sampled using 15-minute transect walks (not sweep nets). Three species, honey bee Apis mellifera, common carder bee Bombus pascuorum and buff-tailed bumblebee B. terrestris, accounted for 85% of bees recorded.
Reduce management intensity on permanent grasslands for birds

A replicated controlled, paired site study in the Netherlands (Kleijn et al. 2001) found that the density of breeding bird territories was not significantly different between 20 fields with meadow bird agreements and 20 control fields, both for all bird species and just for waders. Oystercatcher Haematopus ostralegus, black-tailed godwit Limosa limosa, common redshank Tringa totanus and lapwing Vanellus vanellus were all significantly less abundant on management agreement fields than on control fields. There was no significant difference in the number of territories between field types for three of these species, but oystercatchers had significantly fewer territories on management agreement fields than on control fields (0.13 vs. 0.52). Paired fields were within 1 km of each other, similar in size and soil type. Fertiliser inputs were significantly lower and mowing dates later on fields with management agreements than on conventionally managed fields. Birds were surveyed five times between March and June.
Reduce management intensity on permanent grasslands (several interventions at once)

A paired site comparison in the Netherlands (Kleijn et al. 2001) found more species of bee (Apidae) and hoverfly (Syrphidae) on grassland fields with management agreements to benefit birds or plants than on conventionally managed fields, but not more species of bird or plant. For hoverflies (but not bees) this difference was mostly in May, and could be related to vegetation height, because conventional fields were cut earlier. There were around 50 plant species/field on both field types. The number of bee species was low (average 1.7 bee species/field overall, 85% from just three species). The density of breeding bird territories was not significantly different between 20 fields with meadow bird agreements and 20 control fields, both for all bird species and just for waders. Eurasian oystercatcher Haematopus ostralegus, black-tailed godwit Limosa limosa, common redshank Tringa totanus and northern lapwing Vanellus vanellus were all significantly less abundant on management agreement fields than on control fields. There was no significant difference in the number of territories between field types for three of these species, but oystercatchers had significantly fewer territories on management agreement fields than on control fields (0.13 vs 0.52). The study involved 39 field pairs, one with either a ‘botanical agreement’ (22 field pairs) and/or a ‘meadow bird agreement’ (20 field pairs), the other managed conventionally. Fields were 2 ha on average. Paired fields were within 1 km of each other, similar in size and soil type. Fertilizer inputs were significantly lower and mowing dates later on fields with management agreements than on conventionally managed fields. Fields were surveyed between March and September 2000 (birds five times between March and June, plants and insects four times May to August). More detailed results are presented in a later paper (Kleijn et al. 2004).