Comparisons of Definitions of Soil Bioengineering

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Soil bioengineering is an emerging science that brings together ecological, biological and engineering technology to stabilize eroding sites and restore riparian corridors. Streambanks, lakeshores, tidal shorelines and eroded upland areas all may be effectively revegetated with soil bioengineering techniques if designed and implemented correctly.

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Bioengineering is a low-tech approach for effective yet sensitive design and construction using natural and living materials. The practice brings together biological, ecological, and engineering concepts to vegetate and stabilize disturbed land ... Once established, vegetation becomes self-maintaining.

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Bioengineering is a method of erosion control for slopes or stream banks that uses live shrubs to reduce the need for artificial structures.

Bowers, 1993

Bioengineering is the practice of combining structural components with living material (vegetation) to stabilize soils.

Schiechtl and Stern, 1997

Bioengineering: an engineering technique that applies biological knowledge when constructing earth and water constructions and when dealing with unstable slopes and riverbanks. It is a characteristic of bioengineering that plants and plant materials are used so that they act as living building materials on their own or in combination with inert building materials in order to achieve durable stable structures. Bioengineering is not a substitute; it is to be seen as a necessary and sensible supplement to the purely technical engineering construction methods.

Escheman, no date

By definition, soil bioengineering is an applied science which uses living plant materials as a main structure component . In part, soil bioengineering is the re-establishment of a balanced living, native community capable of self-repair as it adapts to the land's stresses and requirements.

descriptive sciences, physiographic ecology fell into disfavor and disappeared as experimental approaches began to dominate ecology in the mid-1900s. Few studies combining geomorphology and ecology occurred afterwards, probably due to the difficulties with conducting experiments at the appropriate scales of space and time. There was a renewal of interest in these kinds of studies in the 1970s, especially for barrier islands (Godfrey and Godfrey, 1976; Godfrey et al., 1979) where the time scales of vegetation and geomorphic change are fast and closely matched. Swanson (1979; Swanson et al., 1988) provided a modern review of the topic and synthesized his discussion with a summary diagram (Figure 3.1). This diagram traces the many interactions that occur between the realms of geomorphology and ecology that are of interest in soil bioengineering. Another view illustrating the unity of ecology and

Geomorphology Ecology

Geomorphology Ecology

FIGURE 3.1 Relationships between geomorphology and ecology. (A) Define habitat, range. Effects through flora. (B) Define habitat. Determine disturbance potential by fire, wind. (C) Affect soil movement by surface and mass erosion. Affect fluvial processes by damming, trampling. (D) Sedimentation processes affect aquatic organisms. Effects through flora. (E) Destroy vegetation. Disrupt growth by tipping, splitting, stoning. Create new sites for establishment and distinctive habitats. Transfer nutrients. (F) Regulate soil and sediment transfer and storage. (From Swanson, F. J. 1979. Forests: Fresh Perspectives from Ecosystem Analysis. R. H. Waring (ed.). Oregon State University Press, Corvallis, OR. With permission.)

FIGURE 3.1 Relationships between geomorphology and ecology. (A) Define habitat, range. Effects through flora. (B) Define habitat. Determine disturbance potential by fire, wind. (C) Affect soil movement by surface and mass erosion. Affect fluvial processes by damming, trampling. (D) Sedimentation processes affect aquatic organisms. Effects through flora. (E) Destroy vegetation. Disrupt growth by tipping, splitting, stoning. Create new sites for establishment and distinctive habitats. Transfer nutrients. (F) Regulate soil and sediment transfer and storage. (From Swanson, F. J. 1979. Forests: Fresh Perspectives from Ecosystem Analysis. R. H. Waring (ed.). Oregon State University Press, Corvallis, OR. With permission.)

geomorphology is Hans Jenny's CLORPT equation. This is a conceptual model originally created for discussing soil formation (Jenny, 1941) but later generalized for ecosystems (Jenny, 1958, 1961). The basic form of the original equation is:

where

S = any soil property CL = climate

O = organisms or, more broadly, biota R = topography, including hydrologic factors P = parent material, in terms of geology T = time or age of soil

Soil is, therefore, seen as a function of environmental factors including biota of the ecosystem (O) and geomorphology (R). Jenny used the CLORPT equation for understanding pedogenesis and as a basis for his view of landscape ecology (Jenny, 1980). Updates on uses and development of this classic equation are given by Phillips (1989) and Amundson and Jenny (1997). More recently the term biogeomophology, and related variations, is being used for studies of ecology and geomorphology (Butler, 1995; Howard and Mitchell, 1985; Hupp et al., 1995; Madsen, 1989; Reed, 2000; Viles, 1988). This term is analogous to biogeochemistry, which is an important subdiscipline of ecology dealing with the cycles of chemical elements in landscapes.

The history of studies of geomorphology and ecology document that natural ecosystems control or regulate hydrology and the geomorphic processes of erosion and sedimentation. Soil bioengineering attempts to restore these functions in watersheds that have been altered by human land use. The combined use of vegetation

FIGURE 3.2 Energy circuit diagram of the basic hydrologic model.

plantings and conventional engineering that is involved makes this subdiscipline an important area of ecological engineering.

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