Annette Anderson

The role of grassland sward islets in the distribution of arthropods in cattle pastures.

1. It is well documented that cattle reduce their grazing activity in the vicinity of cattle dung, which gives rise to distinct patches, or islets as they have been termed, of longer sward. The influence of such islets on pasture utilisation and agronomic performance has been widely studied, but very little information is available concerning their influence on grassland biodiversity.

The influence of conservation field margins in intensively managed grazing land on communities of five arthropod trophic groups

Abstract.  1. Arthropods, a major component of functional biodiversity within agro‐ecosystems, contribute to sustainability through processes including nutrient cycling and pest control. Extensively managed field margins can help protect this functional biodiversity by providing habitat for beneficial species.

Field margins: a comparison of establishment methods and effects on hymenopteran parasitoid communities

Field margins within intensively managed ecosystems are often seen as a last refuge for biodiversity, and are typically targeted with measures within many agri‐environment schemes. Grassland accounts for 81 million ha of land within the EU; however, the ecology of field margins associated with permanent grassland has not been well studied. This study investigated the effects of experimental field margin measures on hymenopteran parasitoid communities over a 5‐year period. Hymenopteran parasitoids were chosen because they occupy high trophic levels, feed on a diverse range of plant and invertebrate hosts, and are considered good indicators of arthropod diversity. Establishment methods included: fencing, natural regeneration, and reseeding with a wildflower mixture, at three margin widths. Field margin establishment method had a significant effect on abundance of parasitoids. Establishment method did not have a significant effect on parasitoid genera diversity, but did affect parasitoid community composition. Margin width had no significant impact on parasitoid communities. Grazing had a significant negative effect on parasitoid genus richness and community structure. This suggests that structural diversity of vegetation plays an important role in parasitoid community structure. Plant species richness did not significantly affect parasitoid abundance or genera richness. Noxious species within plots resulted in a significantly greater abundance and diversity of parasitoids and of idiobionts in particular. Where plant species richness is limited, simple measures such as fencing of narrow field margins may be as effective at increasing parasitoid taxon richness and abundance (indicators of arthropod richness and abundance) as expensive measures such as reseeding and wider margin widths.

The response of sward-dwelling arthropod communities to reduced grassland management intensity in pastures

Abstract We compared arthropod taxon richness, diversity and community structure of two replicated grassland husbandry experiments to investigate effects of reduced management intensity, as measured by nutrient input levels (390, 224 and 0 kg/ha per year N in one experiment, and 225 and 88 kg/ha per year N in another). Suction sampling was used to collect Araneae, Coleoptera, Hemiptera and Hymenoptera, with Araneae and Coleoptera also sampled with pitfall trapping. Univariate analyses found no significant differences in abundance and species density between treatments. However, with multivariate analysis, there were significant differences in arthropod community structure between treatments in both experiments. Reducing N input and associated stocking rates, as targeted by agri-environment schemes, can significantly alter arthropod communities but without increasing the number of species present. Other approaches that may be necessary to achieve substantial enhancement of sward arthropod biodiversity are suggested.