Both pond creation and restoration provide long term biodiversity gains in agricultural landscapes: implications for conservation

Abstract

Ponds are globally recognised for their unique contribution to freshwater biodiversity. However, due to agricultural intensification and urban development, many ponds within human-dominated landscapes have been lost, while many remaining ponds in such environments have become heavily terrestrialised, which has significantly reduced landscape-scale freshwater biodiversity. To reverse such trends, two main conservation approaches have been employed: pond creation and pond restoration. However, there remains a limited understanding on the longer-term effectiveness of these conservation techniques. This study aimed to quantify and compare long term responses of aquatic macrophyte communities among 56 created (28) and restored (28) ponds across an agricultural landscape in eastern England (United Kingdom). For both approaches, alpha and gamma richness were significantly higher 11+ years after intervention compared to 1–2 years following intervention, but their temporal trajectories differed. Plant colonisation was faster at restored compared to created ponds, with the former displaying a significantly higher taxonomic richness 1–2 and 3–6 years post-intervention. At 11+ years after pond creation or restoration, similar alpha and gamma diversity was recorded for the two conservation approaches. Successive time periods generally demonstrated more similar macrophyte communities within restored and created ponds, and macrophyte compositional differences between created and restored ponds decreased with time. Pond restoration and creation should be used as complementary approaches to create broader abiotic and biotic gradients, in turn supporting different species and community compositions across the landscape. Both approaches are urgently needed to bend the curve on global freshwater biodiversity losses.