Go hard or go home: Major removal of woody vegetation and sediment greatly enhances wetland plant and water beetle diversity recovery in a farmland pond landscape

Abstract

Ponds are important habitats for biodiversity conservation and ecosystem service provisions in farmland settings. Agricultural intensification and cessation of traditional management have resulted in a substantial loss of open-canopy farmland ponds across Europe, resulting in a decline of landscape-scale biodiversity. To recover biodiversity in agricultural pondscapes, recent studies have advocated the restoration of overgrown, ‘late-succession’ ponds via the removal of woody vegetation and/or sediment. However, few studies have documented real-time pond and pondscape species responses to this kind of intervention. Crucially, evidence for how the intensity of intervention shapes biodiversity outcomes has been completely missing. We investigated short-term (1–3 years) pond biodiversity responses to restoration at a typical, medium-sized, predominantly arable farm in eastern England. Wetland plants and water beetles (Coleoptera) were surveyed in 11 restored ponds and four control ponds before and twice following restoration, involving three management prescriptions: (i) major woody vegetation removal only; (ii) major woody vegetation and minor sediment removal; and (iii) major woody vegetation and major sediment removal. Pond restoration involving major woody vegetation and major sediment removal was associated with the greatest uplift in α-diversity for wetland plants. It was also most effective in restoring rare plant species, especially charophytes. Water beetle diversity also responded positively to major woody vegetation and sediment removal, with a significant uplift being observed. Overall, six red-listed species returned to the studied pondscape following restoration interventions. Practical Implication. Our small-scale, explorative study highlights the great potential value of implementing high intensity restoration interventions that combine major woody vegetation and sediment removal over lower intensity options, for maximising freshwater biodiversity and the conservation of rare species in agricultural landscapes.