Artificial reservoirs complement natural ponds to improve pondscape resilience in conservation corridors in a biodiversity hotspot

Abstract

Natural ponds are rich in biodiversity, contributing greatly to regional aquatic biodiversity. Artificial reservoirs used for irrigation can be significant additional features of the landscape. They infill the local natural pondscape, and are attractors for aquatic insects. Here, we determine the extent to which artificial reservoirs represent the local natural pond biota, and how they contribute to the pondscape in conservation corridors used to mitigate the impact of plantation forestry in a global biodiversity hotspot. We did this by: 1) identifying the environmental factors, including plants, that drive dragonfly, water beetle, and water bug species richness, diversity and composition, and 2) determining the value of natural ponds vs. artificial reservoirs for maintaining the population size and expanding the area of occupancy for dragonflies, beetles and bugs in conservation corridors. While vegetation cover was central for maintaining species richness and composition of the assemblages in general, many other environmental variables are necessary to encourage the full suite of local diversity. Artificial reservoirs are attractive habitats to many species, overall increasing area of occupancy for 75% of them (ranging from 62–84% for different taxa). These reservoirs provide complementary alternative habitats to natural ponds, leading to improved ecological resilience across the pondscape. We conclude that maintaining a diverse and heterogeneous pondscape is important for conserving local aquatic insect diversity, and that artificial reservoirs increase the local area of occupancy for a range of pond insects in conservation corridors, and improve the biodiversity value of these pondscapes.

Artificial agri‐environment scheme ponds do not replicate natural environments despite higher aquatic and terrestrial invertebrate richness and abundance

“…Natural and artificial ponds differed in their productivity (as indicated by plant coverage) and surrounding sward height. Ponds with complex aquatic vegetation structure support increased richness and abundance of macroinvertebrates through provision of refuges and more abundant prey populations (Deacon et al, 2018; Zelnik, Gregorič, & Tratnik, 2018). Artificial ponds were surrounded by taller vegetation that can act as a buffer for surface run‐off and aid improved water quality (Usio et al., 2017).…”

“…Agricultural intensification raises concerns about biodiversity loss and degradation in associated ecosystem service delivery (Smith, Renwick, Bartley, & Buddemeier, 2002; Deacon, Samways, & Pryke, 2018). Agri‐environmental schemes (AES) aim to reverse the negative consequences of converting natural habitats to agriculture by compensating farmers for financial losses associated with modifying agricultural practises to benefit biodiversity (Weibull, Ostman, & Granqvist, 2003; Whittingham, 2011).…”

Small mountain reservoirs in the Alps: New habitats for alpine freshwater biodiversity?

“…The reservoirs here have been shown to support a significant proportion of regional biodiversity (38%) and are therefore part of the ecological network sustaining freshwater biodiversity. In South Africa, reservoirs have been shown to provide complementary alternative habitats to natural ponds, leading to improved ecological resilience across the pondscape (Deacon, Samways, & Pryke, ). As biodiversity is under high pressure from climate change, species must move across the landscape to find new habitats according to their thermal requirements (Chen, Hill, Ohlemuller, Roy, & Thomas, ).…”

Contribution of artificial waterbodies to biodiversity: A glass half empty or half full?

“…However, such view has little scientific support and it has been very scarcely explored, except in some particular countries such as UK (Hassall,20a4) or South Africa (Deacon et al, 2018).…”

“…Knowing the contribution of different types of artificial ponds to regional biodiversity is a prerequisite if freshwater biodiversity is to be conserved in our increasingly anthropised landscapes, and is essential for good pond and wildlife management (Picazo et al 2010;Martínez-Sanz et al 2012;Lemmens et al 2013). Furthermore, the ways in which artificial ponds can replace or complement natural ponds is a keystone for future biodiversity conservation (Deacon et al 2018;Oertli 2018). However, to date, this question remains surprisingly underexplored and only few studies have compared the diversity of artificial and natural ponds.…”