The role of pond management for biodiversity conservation in an agricultural landscape

Abstract

Debate surrounds the best way to deal with pond terrestrialization so as to maximize landscape-scale biodiversity. One way of addressing this issue is to re-set succession via management activities, but the merits of this approach relative to non-intervention and pond creation are little known. Manor Farm in Norfolk, UK, possesses around 40 ponds, and each year three to four ponds are subject to management involving tree (de-shading) and/or sediment removal. To determine the consequences of management for pond biodiversity, macrophyte and invertebrate communities were surveyed for replicate ponds covering four ???time since management??? categories: no management, and managed over the periods 1999???2003, 2004???2006 and 2007???2009. Macrophyte diversity was significantly lower in unmanaged ponds compared with ponds managed in 2004???2006 and 2007???2009. In addition, with the exception of Mollusca, invertebrate diversity was significantly lower in the unmanaged ponds compared with all the managed ponds. A tendency was evident for diversity to peak 3???5 years after management and for a subsequent decline in diversity (significant for macrophytes). No distinctive species assemblages were associated with the different pond successional stages, although several species were confined to individual ponds. Although many species were absent from the non-managed ponds, especially in the macrophytes and Coleoptera, few species were unique to these ponds. The principal driver of species turnover in the ponds was shade, which was negatively correlated with macrophyte cover. Shade was substantially higher in the unmanaged ponds, whose species-poor assemblages appeared to be a consequence of low oxygen levels. By arresting succession and restoring macrophyte-dominated early- and mid-successional ponds, management may have an essential role in biodiversity conservation. In pond-rich landscapes, where a high proportion of ponds are heavily terrestrialized, management provides a sustainable means both of preserving heterogeneity in the pond network and preventing the loss of large numbers of species which favour early- and mid-successional pond

Mission possible: diatoms can be used to infer past duckweed (lemnoid Araceae) dominance in ponds

“…diameter), shallow (generally \ 1 m) and, in the case of the farmland ponds, largely alkaline and eutrophic (Table 1). Further details on the history, geography and ecology of ponds in the study area are given in Sayer et al (2012).…”

“…While a number of palaeo-studies have been undertaken in arctic ponds (Douglas and Smol 1994;Keatley et al 2011;Bouchard et al 2012;Stewart et al 2013), few if any studies have focused on temperate European lowland ponds-as in this study. Nonetheless, in recent years, a number of studies have shown the predominantly agricultural pond resource of lowland Europe to be of major importance in terms of aquatic biodiversity conservation (Ruggiero et al 2008;Sayer et al 2012), aquatic-terrestrial energy subsidies (Davies et al 2016) and carbon sequestration (Downing et al 2008), among other roles. Given increasing interest in pond conservation, palaeoecology could have an important role in inferring longterm changes in pond ecology and function in response to environmental impacts.…”

Ecological Drivers of Cladoceran Diversity in the Central European City (Łódź, Poland): Effects of Urbanisation and Size of the Waterbody

“…Norfolk land owners and farm owners are vitally important for the continued survival of pondscapes as the majority of ponds are located in agricultural settings (Boothby et al, 1995a;Sayer et al, 2012).…”

“…Although some individual agricultural ponds in the Astarac region were species poor, they still contributed to the overall regional/pondscape diversity (Céréghino et al, 2008a). Agricultural ponds in Norfolk, UK, supported 57 taxa, and evidence suggested the careful management of farm ponds elevated the invertebrate biodiversity at both an alpha (individual) and gamma (regional) scale (Sayer et al, 2012). In addition, a total of 76 freshwater beetle taxa (one third of the national species pool) were recorded from 54 ponds in intensively farmed regions in Ireland (Gioria et al, 2011).…”

“…Ponds located within woodlands are often ephemeral, providing habitat for rare and endemic species (Brooks, 2000;Armitage et al, 2012) and can act as refugia for macroinvertebrate taxa even when surrounded by industrial, urban landscapes (Spyra and Krodkiewska, 2013). Forest ponds are commonly shaded which has been attributed to reduced macrophyte and macroinvertebrate richness in agricultural areas (Sayer et al, 2012); although forested ponds are just as likely to support uncommon and rare macroinvertebrate taxa (e.g., Agabus striolatus: Coleoptera)…”