Gathering willow
whips for construction of live fascines. Willows (Salix
species) and Poplars (Populus
species) are among the most commonly used groups of woody plants because they
grow easily from cuttings.
Suitability of plants
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Selection of appropriate
species is a major determinant of success for a project. Choices should be
based upon: 1) the compatibility of the plants with the site; and 2) the ability
that they have to achieve one's objectives. Both of these factors depend upon
proper placement within the site. What is more, placement be planned so as
to not create new problems by interfering with other uses. Finally, ongoing
management may be necessary to mitigate undesirable characteristics of the
plants. Ideally however, species should be selected to minimize such maintenance.
Coppin
and Richards (1990) divided plants into four broad categories based on
their suitability for biotechnical stabilization: grasses, herbs, shrubs,
and trees. The advantages and disadvantages of each are examined below.
Grasses
The
advantages of grasses are that they are:
- versatile
and generally inexpensive to get seed for;
- they
become established and grow quickly;
- they
provide dense cover.
The disadvantages
of grasses are that they are:
- generally
shallow rooted;
- may need
maintenance depending upon site
Herbs
The advantages of herbs
are that they are:
- typically deeper rooting
than grasses;
- often able to fix atmospheric
nitrogen into plant available forms (thereby improving soil fertility);
- they are often compatible
with grasses.
The disadvantages are
that:
- in many cases seed is
expensive;
- it is difficult to get
them established;
- most species die back
in the winter (perennials will return in spring, while annuals may seed
and grow anew- either way growth must start over yearly).
Shrubs
The advantages of shrubs
are that:
- they are strong and often
inexpensive- particularly species that can be grown from cuttings such as
red osier dogwood;
- they have deeper roots
than either of the previous categories;
- they are often able to
fix atmospheric nitrogen into plant available forms (thereby improving soil
fertility);
- they don't die back in
the winter;
- they are typically low
maintenance
The disadvantages of
shrubs are that:
- when cuttings are not
an option, they can be expensive
- they can be difficult
to get established
Trees
The advantages of trees
are that:
- they offer substantial
deep roots with significant strength;
- many species such as
Willows and Poplars
can be grown from cuttings, making them inexpensive to work with;
- they don't die back in
the winter;
- they are low maintenance
The disadvantages of
trees are that:
- species that don't grow
from cuttings can be expensive
- they take a long time
to establish
- they are often relatively
slow growing
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Grasses
generally have fine shallow roots
Herbs generally
have deeper more substantial roots than grasses
Shrubs
have deeper stronger roots than the previous categories
Trees have
deep substantial roots with significant strength