Installation of a Riparian Forest by Means of Soil Bio Engineering Techniques—Monitoring Results from a River Restoration Work in Southern Brazil

Soil bioengineering has been applied more and more in different regions of Brazil in recent years. The study in hand presents the installation of “new” riparian forest based on soil bioengineering techniques. This riverbank restoration work was implemented in the year 2010 and two onsite vegetation surveys, one shortly after the construction, and one in 2013. Besides that, the structures of reinforcement work, and its effectiveness were evaluated. By means of the vegetation survey, the applied species were examined for their ability to establish the riverbank in an environmentally sustainable way. Most notably, the species Calliandra brevipes Benth. (Fabaceae, Mimosoideae), Phyllanthus sellowianus Müller Arg. (Euphorbiaceae), Salix humboldtiana Willd. (Salicaceae), Bauhinia forficate Link (Leguminosae), Inga marginata Willd. (Mimosoideae) and Ateleia glazioveana Baill. (Leguminosae, Papilionoideae) showed a good growth development. The proportion of spontaneous vegetation increased significantly, with Pennisetum purpureum Schumach. becoming a dominating species. Resulting from that, the intervention can be assessed as functional and safe, but the strong increase of spontaneous vegetation is undesirable due to less flood resistance. The vegetated riprap could be the best to meet the expectations of the construction elements. Partly, the anchored willows showed as well a good growth development whereas the species used for the hedge brush layer could not develop as expected in large parts of the construction.

Root tensile strength of terrace hedgerow plants in the karst trough valleys of SW China:Relation with root morphology and fiber content

Root tensile strength is commonly affected by root morphology and fiber content,which combinedly affect the effectiveness of terrace hedgerow on controlling soil erosion in sloping farmland.However,the relationships between these root characteristics are still elusive.This study aimed to compare the root tensile strength,root morphologies,and root fiber contents,and quantify their differences among different plant species.Complete root systems of three terrace hedgerow plant species,i.e.,O.bodinieri,V.villosa,and D.lablab L.were sampled for detecting root morphologies and fiber contents at different slope positions on a representative hillslope in karst trough valley.Single root specimens were collected to measure root tensile properties for these three plant species.Results showed that most root morphological parameters were the highest in O.bodinieri,followed by D.lablab L.Three plant species presented the same dominant diameter class as<1.0 mm,and root volumes as<1.50 cm3.Cellulose with contents closing to 50%was the main fiber type,and increased significantly linearly with the increasing root diameter in both O.bodinieri and V.villosa.The highest tensile strength and Young's modulus were found in D.lablab L.,while the best ultimate tensile force and ultimate elongation were displayed in O.bodinieri.Root diameter showed negative power relationships with tensile strength and Young's modulus,a positive power relationship with ultimate tensile force,and a positive linear relationship with ultimate elongation.Our results will deepen the understanding of the terrace hedgerow functions for controlling soil erosion worldwide.