Simple large wood structures promote hydromorpholo

Authors: Francesca Pilotto Gemma L Harvey Geraldene Wharton Martin T Pusch

Publish Date: 2016/01/29

Volume: 78, Issue: 4, Pages: 755-766

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Abstract

The presence of large wood LW in river channels adds an important habitat feature for benthic macroinvertebrates However there has been a lack of studies focusing on the effects of simple wood structures on hydromorphology and macroinvertebrate diversity in surrounding channel areas This study explores whether consistent patterns in LWrelated benthic habitat complexity and macroinvertebrate diversity can be identified across a set of lowgradient streams dominated by fine sediments While the presence of LW did not change the average values of standard hydromorphological variables flow velocity turbulence median sediment grain size and sorting index the coefficients of variation of such variables for wood rich sites were consistently higher than those for wood poor sites velocity 85  higher turbulence 89  grain size 126  sorting index 67  higher In parallel beta diversity was on average 31  higher in the wood rich sites and positively correlated with the amount of LW at the site The hotspots of local alpha diversity were located in the riverbed areas surrounding the LW where taxonomic richness was 83  higher and Shannon–Wiener diversity 39  higher compared to the sites with less wood These results demonstrate that the presence of LW in sandy lowland rivers induces consistent patterns of increased spatial variability of benthic habitats in the surrounding channel areas and this significantly enhances alpha and beta diversity of macroinvertebrate communities Therefore LW should be conserved in river channels wherever possible and its potential for introduction into degraded systems should be explored further because even simple pieces of LW introduced to lowland streams can deliver benefitsThis work has been carried out within the SMART Joint Doctorate Programme ‘Science for the MAnagement of Rivers and their Tidal systems’ funded by the Erasmus Mundus programme of the European Union The authors thank Jürgen Schreiber Marlen Mährlein and Magdalena Czarnecka for field and lab assistance and Drawienski National Park for allowing field work in the Płociczna and Korytnica Rivers and for helpful support of field work

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