Plantation conifer forest can increase the risk of acidification in acid-sensitive catchments with consequences for macroinvertebrates and ecosystem functioning. This study compared headwater streams in forested and non-forested catchments to appraise the distance required for the acid effect on macroinvertebrates to diminish downstream. Strict criteria were followed in the selection of paired streams, including similarities in elevation, aspect, stream order, geographical proximity, geology and soil type, with no inflowing tributaries in the first 2.5 km and no major land-use other than plantation forest and moorland. Consequently two headwater streams (one forested, one non-forested) drained Ordovician sedimentary geology and two headwater streams (one forested, one non-forested) drained Old Red Sandstone (ORS) were selected. All streams drained peaty soils. Up to six sites at 500 m intervals were sampled in triplicate by multihabitat kick sampling. Ecological impact and recovery from acid effects involved the entire macroinvertebrate community, but varied between seasons.Acid-sensitive Ephemeroptera revealed marked effects of episodic acidification, with Baetis rhodani and Rhithrogena semicolorata found to be transient between seasons. The increase in acid-sensitive ephemeropteran species with increasing distance downstream indicates the finite effects of forest mediated acidification on soft water streams in Ireland. Ecological impact appears, therefore, to be localised within the catchment, with ecological recovery occurring a short distance downstream. This is the first study to have reported such results.
The purpose of this study was to consider the relative importance of several habitat variables in explaining the patterns in the structure of macroinvertebrate assemblages in open-water habitats, in relatively intact bogs and fens, which should inform conservation strategies. It was hypothesised that variables relating to the size of the water body would differentiate the communities and that some species would be unique to certain conditions. The macroinvertebrate communities from pools [100 m 2 , 10.1-100 m 2 and Sphagnum hollows were characterised using sweep sampling for eight intact peatland sites across four bog types, and related to habitat variables including pool size, Sphagnum cover and hydrochemistry. Results showed community composition and structure differed significantly between deep, permanent pools and shallow, droughtsensitive Sphagnum hollows, with larger invertebrates, such as Odonates and Dytiscinae, rarely found in the hollows. Sphagnum cover accounted for a substantial amount of the variation in community composition. An examination of life-history strategies found species dependent on predictable conditions for juvenile development to be more abundant in pools. In contrast, taxa that could delay juvenile development until conditions were favourable were more abundant in Sphagnum hollows. These results highlight the importance of habitat heterogeneity in maintaining macroinvertebrate diversity in peatlands.
Peatlands in Ireland have been subject to peat extraction and drainage for many years, with detrimental effects on the fl ora and fauna of the ecosystem. Blanket bog has been listed for protection under Annex 1 of the EU habitats directive, making the conservation of intact bogs as well as the restoration of degraded sites a priority. In order to assess how effective a restoration measure this has been it is important to look at the biodiversity within the site. This study compared the macroinvertebrate and microcrustacean communities in open-water habitats of an intact and a restored mountain blanket bog in County Wicklow over a number of seasons. It also examined the hydrochemistry of both treatments. Hydrochemically there was no difference between the restored and intact pools. Neither was there any signifi cant difference between the two in terms of taxon richness, abundance, community composition or structure. Season was found to significantly affect the structure of the invertebrate communities in both areas. It is not known how long it takes a peatland to return to its natural state. However, we can conclude that the restoration measures implemented fi fteen years ago have provided an aquatic habitat similar to that of the intact site.
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