Wood-soil interactions in soil bioengineering slope stabilization works

Abstract

© iForest -Biogeosciences and Forestry IntroductionSoil bioengineering uses sound engineering practices in conjunction with integrated eco logical principles, using living vegetation and other materials to construct slopes (hill slopes, riverbanks, and lake/shorelines), sta bilize slopes, control erosion, protect wildlife habitats and enhance the functioning of eco systems (Donald & Robbin 1996, Gray & Sotir 1996. Successes of ecological engi neering make it an increasingly attractive al ternative to traditional engineering approa ches, which are often much more expensive to construct and sustain (Li & Eddleman 2002). Vegetation can affect the stability of slopes by modifying the hydrological regime in the soil. Species often used in bioenginee ring applications include willow, poplar, grasses and native shrub species anyway usually fast-growth species.In the last years wood has been widely used as a suitable natural material to be used in soil bioengineering works (Sauli et al. 2002). In particular, among wood characte ristics, its mechanical resistance and its dura tion over time is not always necessary, being its role that of allowing plants colonization in its early stages and so these characteristics are important only in specific situations. Among the various environmental factors in fluencing the performance of the woodenwork, soil plays an extremely important role. Its properties in fact not only determine wood decay rate, but are in turn influenced by wood decomposition which can deeply affect soil physico-chemical and biochemical features. Another important aspect of soil bioengineering is thus emphasized: soil is an element either active in wood decay or pas sive, being itself influenced by wood decay. Soil nutrients cycling and availability are in deed deeply affected by wood decay so that decomposing logs have been referred as "slow-release fertilizers" (Carey 1980). Dead wood is no longer considered as me rely debris, and wood decomposition is wi dely recognized as a key ecological process (Franklin et al. 1987). Decaying wood also plays an important role in soil development because the residues from the degradation of wood components (especially lignin) are one of the substrates for humus formation (Ste venson 1982). Additionally, leaching of dis solved organic matter from decaying wood contributes to the soil organic matter pools and, providing easily available organic sub strates, may fuel soil microbial biomass, thus enhancing its size and/or activity (Yavitt & Fahey 1985, Spears et al. 2003.However, regarding the effect of decaying wood on the physical, chemical and bioche mical properties of the underlying soil, con trasting results were reported and, to our knowledge, not specifically on soil bioengi neering works. Some studies found higher C (carbon) and N (nitrogen) percentages in soil under decaying wood, but did not observe changes in the C:N ratios (Kayahara et al. 1996), while Hafner et al. (2005) reported hi gher C:N ratio beneath decaying logs.Further approaches, aimed to infer effe...

Root Biomechanical Traits in a Montane Mediterranean Forest Watershed: Variations with Species Diversity and Soil Depth

“…Maire can significantly contribute to soil slope stabilization and, providing that appropriate forest management practices are used, could also allow for recolonization by other late-successional trees and woody shrubs, further stabilizing the soil, considering that diverse tree root types greatly contribute to slope stability [65]. Knowledge of the behavior of root systems can be helpful for designing and using bioengineering techniques [16,56,66] and can be useful for mapping slope stability in wooded areas, particularly in Mediterranean environments. Moreover, the results of our experimental data can be used in slope stability models, opening up new research scenarios, especially by including root cohesion in models of mountain stability [6,67].…”

Preparation of Lignin Nanoparticles with Entrapped Essential Oil as a Bio-Based Biocide Delivery System

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Soil bio-engineering for watershed management and disaster mitigation in Ecuador: a short-term species suitability test

“…Gray & Sotir (1996) provided evidence these techniques contributed to soil strength, with positive influences on geotechnical, hydrological, and hydraulic soil characteristics. Lasting beneficial effects on soil physical and chemical properties were reported in other studies (e.g., Schwarz et al 2006, Moscatelli et al 2009. It is clear soil bio-engineering methods are a low cost, environmentally conscience, and effective solution for even large-scale erosion control, and riverbank and slope protection.…”