Local Plant Materials for Soil Bioengineering

Updated June 27, 2008

Bioengineering is a technical term used to describe a variety of techniques that use dormant cuttings from woody plants to alleviate erosion.   Cuttings are taken from species that root easily, then planted in a specific arrangement depending upon the technique.  The beauty of these techniques is that they alleviate erosion, improve water quality, enhance wildlife habitat and look more natural than structural methods.

This bioengineering technique used for shoreline erosion control was developed by Lothar Bestmann in Germany and permits effective, low-cost erosion control without destroying shoreline habitat; in fact, wetlands which enhance the reservoir's shoreline habitat are created.

Selection, and installation of the proper plant material is essential for a successful design. In the case of lakeshore and streambank protection, both herbaceous and woody plants are needed. Herbaceous plants, or wetland plants, will be needed at and near the water's edge. These plants can grow with their roots underwater. This root growth adds considerable strength to the soil. Generally, using several different wetland plant species increases the chance of a successful planting. However, woody plants placed too near the water or water table will not provide good structural strength and may not survive. Woody plants should be used on the upper slope and upland areas where their roots can grow in soil above the water table.

Native tropical vegetation existing at or near the site will give good guidance concerning plant selection.  The use of introduced species allows the potential for increasing the number of different species available.

The availability of plant species, in the appropriate size and quantity, is often a limiting factor in the final selection process. Local nurseries may not carry the types of wetland plants needed. They may be able to propagate the species needed, but this will take 12 to 18 months. A compromise between use of native species and what may be locally or regionally available will be needed to develop a successful design.

Dormancy (definitions):

• a period of rest and "inactivity". Cell division and cell expansion are suspended.
• External forces induce physical/morphological changes. (temperature)
• Escape in time from unstable environmental conditions. (drought) i.e., water stress defoliation, avoidance

Dormancy is not a common term in the tropics but it can be applied for some seeds and some plants.

Some plants have some type of dormancy due to the presence of natural chemicals (endogenous inhibitors or inhibitors that are present in the seeds).

If the plants do not undergo dormancy, they should be planted quickly or they will dry out and die.

Plant species selection

Will the project be for soil binding? Wildlife? Aesthetics? Bioremediation? Other?

Whenever possible, start looking plant species near the bioengineering site.
Preferably native and naturalized species, Retain (when possible), existing vegetation.

Naturalized: been in one place for more than 200 years and having the ability to reproduce naturally.

Plant species selection for wildlife

• Do we want the site to be attractive for wildlife?
• What kind of wildlife? How is their reproductive and growing cycle? What do they eat?
• Are these wildlife species native to the site?

Bioremediation

For clean-up of environmental (soil and water) pollutants by biological means, i.e., nitrogen and phosphorus from water, using plants.

Where do we get information about local vegetative material?

• NRCS Field Office Technical Guides
• Department of Environmental and Natural Resources
• Forest Service
• Extension Service
• Universities

Examples of Plant Materials suitable for bioengineering in the Caribbean Area

GRASSES

Arundo donax - guajana
Bothriochloa pertusa - huracán
Cynodon dactylon - yerba bermuda
Cynodon nelemfuensis - yerba estrella
Dichanthium annulatum - pajón
Digitaria eriantha - pangola
Pennisetum ciliare - buffel
Pennisetum purpureum - elefante
Sporobolus virginicus - matojo de playa
Vetiveria zizanioides - pacholí
Zoysia spp. - grama Zoysia

TREES & SHRUBS

Living trees and shrubs have been used to stabilize the stream banks, through a variety of Stream Bioengineering techniques. Facines, brush mattresses, and timber cribs are all being tested and evaluated as to their effectiveness. These biotechnical streambank protection techniques help to stabilize slopes, improve infiltration, filter runoff, improve habitat, and enhance aesthetics.

Examples of TREES & SHRUBS

• Bucida buceras - úcar, gregre
• Bursera simaruba - almácigo, turpentine tree
• Clusia rosea - Cupey
• Cordia sebestenea - vomitel, geiger tree
• Erythrina poeppigiana - Bucayo, bucare, mountain immortale
• Glyricidia sepium - Mata ratón, Glyricidia
• Hibiscus spp. - Hibiscos
• Lagerstroemia indica - astromelia
• Mangrove species (Rhizophora, Avicenia, Laguncularia, Conocarpus)
• Pictetia aculeata - Fustic

FORBS

Transplants of all types are available, such as bare-root, container-grown, or balled and burlapped. Seeding of grasses and/or forbs (broad-leaved herbaceous plants and wildflowers) is also an option. If at all possible, local native species should be used because of their greater wildlife benefit and their adaptation to local climatic conditions. This technique entails greater cost and more installation work than live staking, but a greater variety of plants can be used. Spacing and layout will be determined by the plants selected.

• Rhoeo spathacea- Sanguinaria
• Sansevieria hyacinthoides - Lengua de chucho, lengua de suegra, lengua de vaca, sweet Sansevieria
• Hymenocallis caribaea - Lirio blanco, Spyder lilly

Ferns - many species

Plants (ferns, wildflowers, vines, vetch and others) are also a viable tools for soil stabilization and sediment control. They can be transplanted directly from adjacent sites (may available from specialist nurseries) or be seeded.

It is essential to use care in non-native species selection. The introduction of a species that may be considered a nuisance (such as damaging to other native species), noxious (poisonous) or a weed must be avoided.

• Commelina sp. - cihítre
• Nicolaia elatior - Flor de cera, Torch ginger
• Zingiber spp. - Jengibre, Ginger
• Sphagneticola trilobata - Margarita, Bay Biscayne creeping oxeye
• Batis maritima - Barilla, Saltwort

Local experience: To be recommended for hedgerow, windbreak/shelterbelt and/or bioengineering projects

• Shoot behavior of Erythrina poeppigiana
• Shoot behavior of Glyricidia sepium
• Shoot behavior of Arundo donax

PMF in cooperation with the Interamerican University, San Germán Campus