Influence of some physicochemical and biological parameters on soil structure formation in alluvial soils

Abstract

This study examines the role of abiotic (texture, calcium carbonates or iron) and biotic parameters (earthworm and enchytraeid activities) on the initial phases of soil aggregation. Our research focused on humus forms in alluvial soils, which are considered as young and heterogeneous environments. We hypothesized that the soil structure formation is determined by both the nature of the recent alluvial deposits and the soil fauna. For this purpose, six sites were chosen throughout two types of softwood forests (willow and alder forest) representing two stages of vegetation succession. Evidence of soil texture influence on aggregate stability was observed. A dominance of a coarse sand fraction caused a quick colonization of enchytraeids and epigeic earthworms while a silty texture favoured the presence of anecic earthworms, thus increasing the aggregate stabilisation. Iron forms, acting as cementing agents, were observed in the coarse silt, while calcium carbonates were equally distributed among the textural fractions. Active calcium carbonate fraction, binding organic matter with mineral components, was not found in the coarse sand fraction. In conclusion, the tree age cannot alone be used as an indicator of the humus form evolution but biological and physicochemical parameters also influence the initial steps of soil structuration.

Impact of flood deposits on earthworm communities in alder forests from a subalpine floodplain (Kandersteg, Switzerland)

“…We hypothesize that our low values may be due to the characteristics of alluvial soils, where earthworm abundance is generally lower according to Edwards and Bohlen [13]. Moreover, the maximum abundance and biomass found in this study are similar to those measured in a Swiss mountain level floodplain [22]. Eight species and subspecies, all inventoried in Switzerland, were determined in our study plots.…”

Spatio-temporal heterogeneity of riparian soil morphology in a restored floodplain

“…However, in order to use soils in monitoring programs it is necessary to understand how they change over space and time (Cole and Kentula, 2011). To date, most research on the impact of river restoration on floodplain soils have focused on processes such as organic matter accumulation and decomposition (Sifneos et al, 2010;Stein et al, 2009;Bush, 2008), litter decomposition (Ballantine and Schneider, 2009), or denitrification (Orr et al, 2007;Sutton-Grier et al, 2010). There is thus a need to integrate soil physical, chemical and biological factors and processes (Heneghan et al, 2008) and soil temporal dynamics (Ballantine and Schneider, 2009) into the planning and assessment of river restoration projects.…”

Patterns of earthworm communities and species traits in relation to the perturbation gradient of a restored floodplain

“…However, their impact on the terrestrial ecosystems of floodplains remains poorly understood, especially with respect to the soil fauna. Soil organisms include many potential indicators of river restoration success but this potential has not yet been studied much (Bullinger-Weber et al, 2007;Fournier et al, 2012;Guenat et al, 1999). Among the candidates, earthworms are recognised as good bioindicators of soil conditions in alluvial ecosystems (Bullinger-Weber et al, 2012;Salomé et al, 2011) and could therefore provide useful information for monitoring of restoration projects.…”