Resprout and Survival of Willow (Salix) Cuttings on Bioengineering Structures in Actively Eroding Gullies in Marls in a Mountainous Mediterranean Climate: A Large-Scale Experiment in the Francon Catchment (Southern Alps, France)

Abstract

Improving the understanding of the role of vegetation and bioengineering structures on erosion and sedimentation control, especially in torrent-prone catchments in a mountainous Mediterranean climate, has become a key issue today for the scientific community working in ecological engineering and restoration ecology. The objective of this study was to evaluate the performance of willow (Salix) cuttings in resprouting and survival on bioengineering structures in actively eroding gullies in marls and to identify the factors influencing this performance. Measurements were taken from 2008 to 2011 on 336 bioengineering structures, namely brush layers on wooden sills (BL) and brush layers with brush mats on wooden sills (BLM), using 8890 cuttings of Salix purpurea and Salix incana. These structures were built in 18 gullies of the Francon Catchment in marls (73 ha) in the Southern French Alps. After four growing seasons, the results revealed a total cutting survival rate of 45%. They also demonstrated that in BLM, brush mats provided better survival (56%) than brush layers (37%). In BL, brush layers alone showed 51% cutting survival. Cutting resprout and survival were observed for all structure aspects. They were positively related to increasing gully size and vegetation cover on gully sides. The results of this large-scale experiment clarified previous data obtained on a limited sample of bioengineering structures, providing further detail and showing that it is possible to use such structures made of willow cuttings to revegetate actively eroding gullies in marls within a mountainous Mediterranean climate.

Effects of wood chip amendments on the revegetation performance of plant species on eroded marly terrains in a Mediterranean mountainous climate (Southern Alps, France)

“…Experimental knowledge for ecological restoration of marly eroded lands is available through the voluminous research conducted in these areas (Rey, 2009;Erktan et al, 2016;Burylo et al, 2014). These studies have researched gully beds, where vegetation can counter erosive forces and trap sediment Rey and Labonne, 2015). Therefore it appeared that vegetation could also be profitable in gully slopes where soil fertility is very low (soil loss, low soil moisture and lack of an organic layer) and where natural vegetation is nearly nonexistent.…”

Soil and water bioengineering: Practice and research needs for reconciling natural hazard control and ecological restoration

“…A diversity of plant species would also enable a manager to "cover all options"; for example in the case of a particular species becoming susceptible to abiotic/biotic factors, the loss of one species would be less likely to compromise the aims of the project. Referring to the study of Erktan et al (2013), Rey and Labonne (2015) suggested using only one species to build brush layers and mats in eroded gully floors, but to use different species between structures along the gully floor, thus reconciling natural hazard mitigation with improved biodiversity.…”

Fire Severity Drives the Natural Regeneration of Cytisus scoparius L. (Link) and Salix atrocinerea Brot. Communities and the Germinative Behaviour of These Species

“…can produce 7650 seeds m −2 •year −1 [53]. Seed dispersal is favoured by wind and water [54]. Salix seeds are very lightweight (<0.005 g) could produce about 5•10 6 seeds kg −1 [55] and they lose their viability very quickly in natural conditions [56], (personal observation), with 50% reduction in just one or two weeks [56].…”