Biodiversity outcomes of novel land management within semi-natural grassland: a landscape-scale experiment

Hawkes, Robert (2020) Biodiversity outcomes of novel land management within semi-natural grassland: a landscape-scale experiment. Doctoral thesis, University of East Anglia.

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Knowledge of land-use history and the autecological requirements of priority species encourages novel conservation management interventions that incorporate physical-disturbance and spatio-temporal variability. This thesis evaluates the biodiversity outcomes of such interventions through a landscape-scale management experiment conducted across an extensive (c.3,850 ha) semi-natural grassland dominated by closed-swards. Treatments (deep- and shallow-cultivation) were built-up over three years (2015-2017) creating 40 x 4-ha plots, each comprising four 1-ha sub-plots: repeat cultivation, first-time cultivation, one-year-fallow and two-year-fallow. The study focussed on the responses of two ‘flagships’ for which the area is designated (Eurasian Stone-curlew Burhinus oedicnemus and Woodlark Lullula arborea), vascular plants and invertebrates from eight taxonomic groups. Unlike unmodified grassland controls, recently-cultivated treatments created suitable Stone-curlew nesting habitat. Five GPS-tracked adult Stone-curlews also selected treated plots over unmodified grassland as foraging areas both during and after breeding attempts. Woodlark numbers were higher on plots closer to woodland and on treated plots, regardless of cultivation depth. Sampling of 132,251 invertebrates from 878 species and 28,846 observations of 167 plant species showed both treatments doubled the overall richness of priority species (rare, scarce or threatened). Crucially, those invertebrates associated with dry-open habitats and a priori predicted to require physical disturbance responded most strongly to treatment, confirming the success of bio-regional analyses in targeting appropriate interventions within this system. Within plots, most sub-plots supported distinct assemblages, suggesting heterogeneity in treatment (shallow- and deep-cultivation) with frequent reapplication (providing continuity of fallowed and recently disturbed areas) maximises biodiversity outcomes. To optimise the cumulative richness of non-priority and priority invertebrates, these treatments need to take place across 40 – 60% of the landscape. Based on these findings, this thesis encourages the widespread adoption of complex physical-disturbance treatments across semi-natural dry grassland and lowland heathland. Incorporating such interventions into future agri-environment schemes would help to facilitate this recommendation.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Chris White
Date Deposited: 15 Apr 2021 12:22
Last Modified: 31 Oct 2021 00:39


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