Assessment of the Impact of Phased Felling on the Ecological Quality of First Order Streams and Subsequently Salmonid Rivers

Connie O’Driscoll, Elvira de Eyto, Michael Rodgers, Mark O’Connor, Zaki-ul-Zaman Asam, Liwen Xiao

Proceedings of the 14th International Peat Congress


blanket-peat-forests, diatoms, low-alkalinity, macroinvertebrates, nutrients

O’Driscoll et al 2012: Assessment of the Impact of Phased Felling on the Ecological Quality of First Order Streams and Subsequen


Theme VII. Ecology and management on forested peatlands


Little is known about the impacts of forestry clearfelling and associated nutrient enrichment on phytobenthic assemblages in upland peat catchments, characterised as oligotrophic and naturally acidic. The objective of this study was to investigate the short term impact of forest harvesting on the phytobenthos and benthic invertebrates in three neighbouring peatland catchments. To achieve this multiple before/ after-control-impact (MBACI) experimental design was used. Three headwater streams sampled twice before harvesting and twice after harvesting and two undisturbed control streams sampled at the same dates were used. Significant increases in PO4-P concentrations were detected after the perturbation increasing from 4.3 to 108 μg/ L. Macroinvertebrate assemblages were severely impacted. The EPT, diversity and species richness decreased from 4, 1.3 and 7 to 1, 0.2 and 2 respectively. In contrast the diatom assemblages were not affected significantly. Therefore caution should be exercised when using diatoms as indicators in acidic catchments. No impact was observed above and below the confluence in the main river of one of the headwater streams. It can be concluded from this study that phased felling is therefore recommended as an efficient protection to mitigate short-term effects of harvesting impacts in salmonid streams.