Macroinvertebrate community assembly in pools created during peatland restoration

Abstract

Many degraded ecosystems are subject to restoration attempts, providing new opportunities to unravel the processes of ecological community assembly. Restoration of previously drained northern peatlands, primarily to promote peat and carbon accumulation, has created hundreds of thousands of new open water pools. We assessed the potential benefits of this wetland restoration for aquatic biodiversity, and how communities reassemble, by comparing pool ecosystems in regions of the UK Pennines on intact (never drained) versus restored (blocked drainage-ditches) peatland. We also evaluated the conceptual idea that comparing reference ecosystems in terms of their compositional similarity to null assemblages (and thus the relative importance of stochastic versus deterministic assembly) can guide evaluations of restoration success better than analyses of community composition or diversity. Community composition data highlighted some differences in the macroinvertebrate composition of restored pools compared to undisturbed peatland pools, which could be used to suggest that alternative end-points to restoration were influenced by stochastic processes. However, widely used diversity metrics indicated no differences between undisturbed and restored pools. Novel evaluations of restoration using null models confirmed the similarity of deterministic assembly processes from the national species pool across all pools. Stochastic elements were important drivers of between-pool differences at the regional-scale but the scale of these effects was also similar across most of the pools studied. The amalgamation of assembly theory into ecosystem restoration monitoring allows us to conclude with more certainty that restoration has been successful from an ecological perspective in these systems. Evaluation of these UK findings compared to those from peatlands across Europe and North America further suggests that restoring peatland pools delivers significant benefits for aquatic fauna by providing extensive new habitat that is largely equivalent to natural pools. More generally, we suggest that assembly theory could provide new benchmarks for planning and evaluating ecological restoration success.

Water‐level dynamics in natural and artificial pools in blanket peatlands

“…Höper et al, 2008) where peatlands have been damaged by artificial drainage, ditches in United Kingdom peatlands are being blocked. This restoration activity results in the creation of thousands of small pools within the blocked ditches, which in sum can amount to a large area of open water (Brown, Ramchunder, Beadle, & Holden, 2016;Holden et al, 2017;Parry, Holden, & Chapman, 2014). It is not known to what extent the hydrological functioning of these artificial peatland pools is similar to that of natural pools.…”

Positive trends in plant, dragonfly, and butterfly diversity of rewetted montane peatlands

“…Like other aquatic macroinvertebrates, dragonflies show very sudden positive responses to rewetting (Brown et al ), while species fluctuations depend mostly on pond quality. Almost no dragonflies are found in degraded, dry, and shaded peatlands, while they immediately colonize rewetted sites with unshaded water bodies (Elo et al ) as created by peat extraction for dam building.…”

“…For example, open water pools, that are created during peatland rewetting, are used by aquatic macroinvertebrates like Coleoptera and Odonata (Brown et al 2016). Increased soil moisture benefits craneflies (Carroll et al 2011), and a raised water table and improved tree stand structure favor mire ants (Punttila et al 2016).…”

“…In peatlands, not only plants, but peatland specialists and generalists of Odonata, Heteroptera, Coleoptera, Diptera, Lepidoptera, and Hymenoptera, are negatively affected by habitat degradation and fragmentation, and might benefit from rewetting (Spitzer & Danks ; Brigić et al ). For example, open water pools, that are created during peatland rewetting, are used by aquatic macroinvertebrates like Coleoptera and Odonata (Brown et al ). Increased soil moisture benefits craneflies (Carroll et al ), and a raised water table and improved tree stand structure favor mire ants (Punttila et al ).…”

Freshwater biodiversity conservation through source water protection: Quantifying the potential and addressing the challenges

“…Some studies examining wetland birds, invertebrates, and amphibians have found evidence of positive change in population abundance or species presence, although these changes are not necessarily sustained over time (Brown, Smith, & Batzer, 1997;Hapner et al, 2011;Ruhi et al, 2012). Restored peatlands have been shown to support freshwater communities comparable with those in natural wetlands (Brown, Ramchunder, Beadle, & Holden, 2016). Created compensatory wetlands often fail to achieve the same ecosystem functions as restored or rehabilitated natural wetlands (Brown & Veneman, 2001;Español, Gallardo, Comín, & Pino, 2015;Spadafora et al, 2016;Whigham, 1999).…”