Upland grassland agri-environment impacts on invertebrate biodiversity

Abstract

Recent major declines in invertebrate abundance linked to agricultural intensification and land-use change have been documented. There has been a widespread lack of environmental monitoring and assessment of agri-environment schemes, with a lack of evidence supporting clear benefits of agri-environment schemes for invertebrate communities.

This thesis aimed to investigate the efficacy of agri-environment schemes on invertebrate total and functional biodiversity to provide management recommendations to enhance invertebrate biodiversity in upland grasslands.

Upland grassland swards were floristically poor, and were dominated by perennial ryegrass.

Agri-environment scheme management increased ground-dwelling invertebrate abundance and richness. Soil microarthropod total abundance and species richness were similar between agri-environment scheme and conventionally managed grasslands but effects were different in the two most dominant taxa, Oribatid mites and Collembola springtails. Aerial insect functional abundance and diversity were mainly driven by landscape scale habitat coverage effects rather than agricultural management, though agri-environment scheme management had an effect on some functional groups. The remotely-sensed Enhanced Vegetation Index (EVI) data suggested agri-environment scheme semi-improved grasslands were the least variable in terms of productivity and subsequently the most stable grasslands studied.

Results suggest invertebrate web structure may benefit from agri-environment scheme management. Continued surveillance and monitoring is necessary to establish the impact of AESs and how agricultural management impacts invertebrate population trends. Increasing the grassland sward diversity, by limiting dominance of perennial ryegrass is recommended to maximise benefits for multiple invertebrate groups and livestock production. Farming is likely to be challenged by ongoing global climate change and the frequency and severity of extreme weather events. Perturbations to the upland grasslands such as flooding and drought will have consequences for production, biodiversity and associated ecosystem services. As such, policy encouraging floristic diversity and minimising soil disturbance expanding the extent of semi-improved grasslands is needed to result in environmental outcomes for biodiversity.

Thesis embargoed until 31 December 2022.

Date of Award	Dec 2021
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Department of Agriculture, Environment and Rural Affairs
Supervisor	Neil Reid (Supervisor) & Mark Emmerson (Supervisor)