Evolution of shrub communities in soil bioengineering projects on Vesuvius
From 1998 to 2005, on Vesuvius, a great number of soil bioengineering projects were implemented to recover landslides and to stabilize slopes.
Soil bioengineering uses plants to reinforce, enrich and green eroded and bare soils, promoting ecologic succession.
To help initial soil stabilization, it is possible to use timber logs or others biodegradable materials.
It has been verified that in the Vesuvius territory, summer dryness and soil porosity don’t allow the success of the soil bioengineering techniques developed in Austrian Alps. In order to solve this problem, those techniques have been adjusted, preferring the use of plants instead of woody cuttings.
Is soil bioengineering ecologically effective in the Mediterranean area? Can those artificial ecosystems, rebuilt with few species, achieve the climax community?
A vegetation inventory of two soil bioengineering projects, built in 2002, was made in 2012 and 2013. The two projects are located close to each other, on the East side of Vesuvius Great Cone, at 995 m AMSL, but with different local humidity conditions.
In order to check this, in 2013, a vegetation inventory was made in a nearby, at 970 m AMSL. This soil bioengineering project, built in 2004, was mechanically stabilized with timber logs, but without any plants
The results refer to the worst conditions on Vesuvius' territory. On the volcano´s top the soil is very recent, porous, and poor, the weather is windy, snowy and harsh in winter, sunny and hot in summer.
In the project, where the slope was stabilized only with timber logs, no new plants were inventoried.
In the two monitored soil bioengineering projects, plants have colonized the whole work surface. In addition to the species used (2 trees, 5 shrubs and 2 subshrubs) other 36 species were inventoried: mosses, mushrooms, grasses, and shrubs, naturally coming from the surrounding areas. Trees were present along old temporary runoff lines.
Soil bioengineering projects, on Vesuvius, proved their effectiveness not only in consolidating slopes, recovering landslides, and building trails, but also in rebuilding ecosystems, even in the difficult Mediterranean conditions.
Along temporary surface runoff lines, soil bioengineering projects enable to reduce and mitigate the hydraulic erosion. Also, they allow tree growth, even in arid shrublands.