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

Abstract

Abstract.Floodplains have been intensively altered in industrialized countries, but are now increasingly being restored. It is therefore important to assess the effect of these restoration projects on the aquatic and terrestrial components of ecosystems. However, despite being functionally crucial components of terrestrial ecosystems, soils are generally overlooked in floodplain restoration assessments.We studied the spatio-temporal heterogeneity of soil morphology in a restored (riverbed widening) river reach along the River Thur (Switzerland) using three criteria (soil diversity, dynamism and typicality) and their associated indicators. We hypothesized that these criteria would correctly discriminate the post-restoration changes in soil morphology, and that these changes correspond to patterns of vascular plant diversity.Soil diversity and dynamism increased 5 yr after the restoration, but some typical soils of braided rivers were still missing. Soil typicality and dynamism were correlated to vegetation changes. These results suggest a limited success of the project, in agreement with evaluations carried out at the same site using other, more resource-demanding, methods (e.g., soil fauna, fish diversity, ecosystem functioning).Soil morphology provides structural and functional information on floodplain ecosystems. The spatio-temporal heterogeneity of soil morphology represents a cost-efficient ecological indicator that could easily be integrated into rapid assessment protocols of floodplain and river restoration projects.The follow-up assessment after several major floods (≥ HQ20) should take place to allow for testing the longerterm validity of our conclusion for the River Thur site. More generally, it would be useful to apply the soil morphology indicator approach in different settings to test its broader applicability.

Carbon storage and soil organic matter stabilisation in near-natural, restored and embanked Swiss floodplains

“…Our results confirm that soil morphology inherently contains structural and functional information on floodplain ecosystems as demonstrated previously by Fournier et al (2013) on the Thur floodplain. We showed that soil morphology and some related soil properties ( particle-size distribution, total iron and CaCO 3 contents of the uppermost humic layer) are also adequate indicators explaining the variability of carbon storage and SOM stabilisation in floodplains differing in the level of human disturbance (i.e.…”

“…Previous researches performed on the Thur River have demonstrated that the river widening has increased soil diversity (Fournier et al, 2012) and the most striking changes occurred where post-restoration fluvial dynamics created diverse and dynamic pattern of soils (Fournier et al, 2013). In addition, Samaritani et al (2011) showed that the Thur restored section exhibited both a larger range and a higher heterogeneity of organic C pools (microbial C and water extractable organic C) than the embanked section.…”

“…A preliminary soil survey was performed using an auger boring in order to evaluate the variability of soil morphologies in the floodplains (Fournier et al, 2013). Along transects perpendicular to the river flow, a total of 104, 260 and 125 borings were performed in the Rhine floodplain (3 transects), the Emme floodplain (10 transects) and the Thur floodplain (6 transects).…”

Lateral heterogeneity of soil physicochemical properties in riparian zones after agricultural abandonment

“…Altitude is a complex and multivariate factor that always related to substrate, flood, and vegetation 37 , which have influence on soil properties 38,39 . Along with the distance from river edge, erosion and sedimentation processes showed sharp lateral gradients 40 , resulting in the lateral heterogeneity of soil texture 19 .…”

Variability of flow discharge in lateral inflow-dominated stream channels

“…Ogden and Julien, 1993;Redano and Lorente, 1993;Wheater et al, 2000;Zhang et al, 2001;De Michele and Bernardara, 2005;Haberlandt et al, 2008;Valipour, 2012;Bewket and Lal, 2014) and the great heterogeneity of soil types at the ground surface (e.g. Jencso et al, 2009;Fournier et al, 2013) and surface saturation (e.g. Schumann et al, 2009;Riley and Shen, 2014) over a watershed, creates a very complex runoff process on the land surface.…”