Dr Robert Hawkes

Experimental evidence that novel land management interventions inspired by history enhance biodiversity

To address biodiversity declines within semi-natural habitats, land management must cater for diverse taxonomic groups. Integrating our understanding of the ecological requirements of priority (rare, scarce or threatened) species through ‘biodiversity auditing’, with that of the intensity and complexity of historical land use, encourages novel forms of management. Experimental confirmation is needed to establish whether this enhances biodiversity conservation relative to routine management.

Biodiversity auditing and historical land use of dry-open terrestrial habitats in Breckland (Eastern England) both encourage management incorporating ground disturbance and spatio-temporal variability. To test biodiversity conservation outcomes, we developed forty 4-ha management complexes over three successive winters, of which 20 were shallow-cultivated (rotovation) and 20 deep-cultivated (ploughing), stratified across 3,850-ha of closed-sward dry grassland and lowland heathland (collectively ‘dry grassland’). Complexes comprised four 1-ha subtreatments: repeat-cultivation, first-time cultivation, 1-year-old fallow and 2-year-old fallow. We examined responses of vascular plants; spiders; true bugs; ground, rove and ‘other’ beetles; bees and wasps; ants; and true flies on treatment complexes and twenty-one 4-ha untreated controls. Sampling gave 132,251 invertebrates from 877 species and 28,846 plant observations from 167 species.

Resampling and rarefaction analyses showed shallow- and deep-cultivation both doubled priority species richness (pooling subtreatments within complexes) compared to controls. Priority spider, ground beetle, other beetle and true bug richness were greater on both treatments than controls. Responses were strongest for those priority dry-open habitat associated invertebrates initially predicted (by biodiversity auditing) to benefit from heavy physical disturbance.

Assemblage composition (pooling non-priority and priority species) varied between subtreatments for plants, ants, true bugs, spiders, ground, rove and other beetles; but only 1-year-old fallowed deep-cultivation increased priority richness across multiple taxa.
Treatments produced similar biodiversity responses across various dry grassland ‘habitats’ that differed in plant composition, allowing simplified management guidance.

Synthesis and applications. Our landscape-scale experiment confirmed the considerable biodiversity value of interventions inspired by history and informed by systematic multi-taxa analysis of ecological requirements across priority biota. Since assemblage composition varied between subtreatments, providing heterogeneity in management will support the widest suite of species. Crucially, the intended recipients responded most strongly, suggesting biodiversity audits could successfully inform interventions within other systems.

Date

01 January 2021

RSPB Authors

Dr Robert Hawkes, Dr Jen Smart

Authors

Hawkes, Robert W Smart, Jennifer Brown, Andy Jones, Helen Lane, Steve A Lucas, Colin McGill, James Owens, Nick Ratier Backes, Amanda Webb, Jon R

Published in

Journal of Applied Ecology

Effects of experimental land management on habitat use by Eurasian Stone-curlews

Effective conservation is often informed by focal species studies to identify beneficial land management interventions. For nocturnal or cryptic species, quantifying habitat use across individually marked animals can allow unbiased assessment of intervention efficacy and identify other important habitats. Here, using a landscape-scale experiment, we examine whether interventions intended to create nesting habitat for the largely nocturnal Eurasian Stone-curlew Burhinus oedicnemus within semi-natural grassland also provide foraging habitat. GPS loggers were fitted to five adult Stone-curlews during the breeding season within an extensive area of semi-natural grassland (3850 ha, hereafter ‘grassland’), surrounded by a mosaic of arable cropland (total study area 118 600 ha). The largely closed-sward grassland was diversified by experimental ground-disturbance plots (the intervention) prior to this study. We used the GPS fixes to identify 1881 foraging locations (510 during nesting and 1371 post-breeding) across the grassland and surrounding landscape. Most foraging locations were close to the nest-site during the nesting period (90% within 1 km) or day-roost during post-breeding (90% within 5 km), but birds travelled up to 4.1 km from these sites during nesting and 13 km post-breeding. Stone-curlews were two- (by night) or three-times (by day) more likely to select disturbed-grassland over unmodified grassland for foraging during nesting, and c. 15 times more likely to do so post-breeding. Spring-sown crops and pig fields or manure heaps were also selected over grassland for nocturnal foraging. Given that central place foraging occurs in this species, conservation efforts that promote breeding attempts through ground-disturbance should ensure suitable foraging habitat is near the nest (<1 km). Creating multiple areas of disturbed-ground close to the edge of large grassland blocks can provide a network of nesting and foraging habitats, while allowing access to foraging habitats on the surrounding arable farmland. Similar interventions may benefit other disturbance associated grassland waders.

Date

26 February 2021

RSPB Authors

Dr Robert Hawkes, Dr Jen Smart

Authors

Hawkes, Robert W Smart, Jennifer Brown, Andy Green, Rhys E Jones, Helen Dolman, Paul M

Published in

Animal Conservation

Multi-taxa consequences of management for an avian umbrella species

Whether management for so-called umbrella species actually benefits co-occurring biota has rarely been tested. Here, we studied consequences for multiple invertebrate taxa of two ground-disturbance treatments designed to support an avian umbrella species (Eurasian stone-curlew, Burhinus oedicnemus)

Date

06 May 2019

RSPB Authors

Dr Jen Smart

Authors

Hawkes, Robert W. Smart, Jennifer Brown, Andy Jones, Helen Lane, Steve Wells, Doreen Dolman, Paul M.

Published in

Biological Conservation 236: 192-201.

Experimental evidence that ground-disturbance benefits Woodlark Lullula arborea

To determine whether ground-disturbance increased Woodlark Lullula arborea abundance, we examined responses over 3 years to four treatments varying in establishment method (shallow- or deep-cultivated) and complexity (homogeneous or 'complex-mosaics' comprising fallow and recently cultivated subplots), plus controls, replicated across the largest lowland grass-heath in the UK. Abundance increased through the study and was higher on plots closer to woodland and across all treatments. Within complex-mosaics, Woodlark preferentially used recently cultivated subplots over 1- or 2-year-old fallows. Regardless of treatment detail, providing suitable foraging habitat within c. 45 m of woodland, through annual ground-disturbance, can increase Woodlark abundance within lowland grass-heaths characterized by closed swards.

Date

01 April 2019

Authors

Hawkes, R. W. Smart, J. Brown, A. Jones, H. Dolman, P. M.

Published in

Ibis