Roadside Revegetation

IMPLEMENTATION GUIDES
Installation Methods – Compensations can be made for sites with poor soils or dry climates.
One option is to install longer cuttings. Studies have shown that higher survival rates and
greater vegetative growth can be achieved with longer cuttings (Rossi 1999). This is especially
important on drier sites, since longer cuttings access deeper soil moisture. Cuttings up to 2 feet
in length have been shown to produce better survival and growth on harsher sites (McElroy
and Dawson 1986; Rossi 1999). In areas where freeze-thaw potential is high (see Section 5.6.2,
Freeze-Thaw), shorter cuttings have a greater likelihood of being pushed out of the ground
before they can form roots to anchor them in place. Survival rates are also affected by the
quality of planting methods. For instance there can be a significant decrease in survival when
cuttings are planted without good soil–to-stem contact and many large air pockets. Section
10.3.3, Installing Cuttings, covers the different methods of installing cuttings.
Plant Maintenance– Survival potential can also be increased if the plants are maintained during
the first year after planting, including the control of competing vegetation and protection
from animal browse (see Section 10.4, Post Installation Care of Plant Materials).
Determine Cutting Needs
Once the survival and rooting potentials have been determined, the quantity of cuttings to
collect can be calculated. The information needed for determining cutting quantities and
cutting spacing (density) is:
◾◾
Rooting potential
◾◾
Survival potential
◾◾
Target plant density
◾◾
Area to plant
◾◾
Desired established plant densities
◾◾
Length of cuttings
An example of how to calculate cutting quantities
and planting spacing is shown in Figure 10-56. In this
example, the project objective is to stabilize the slope by
installing willow stakes. In the short term, this practice
will increase slope stability by physically “pinning”
the surface soil. The primary benefit to slope stability,
however, will develop over time as the roots of the establishing
willows begin to tie the soil particles together
and increase soil strength. The desired spacing between
established plants is 6 ft. When inventories are taken
one year after planting, they should find an established
plant approximately every 6 feet (D), or approximately
303 established plants for the entire planting site (E).
To achieve the desired density of established plants, we must determine how many cuttings
to plant and the average spacing between installed cuttings. This determination is based
primarily on the rooting and survival potentials (see Section 10.2.2.4, Determine Rooting
Potential, and Section 10.2.2.5, Determine Survival Potential). In this example, the rooting
potential was 68 percent based on rooting potential tests. The survival factor was estimated
to be around 35 percent from previous experiences on similar sites. These factors are used in
the equation shown in Line F, to calculate the number of cuttings needed to install. To obtain
303 established plants, it would be necessary to install approximately 1,271 cuttings. This is
approximately four times the number of established plants. It is necessary to install this many
to compensate for the number of cuttings that either do not root, or root and do not survive
the summer. The planting spacing is calculated using the equation in Line I. Cuttings must be
installed at half the distance of the desired established plant spacing. Since the site conditions
A Area to plant: 0.25 acres Area that will be planted with cuttings
B Rooting potential: 68 % Percent of cuttings that root under
ideal rooting environment
C Survival potential: 35 % Percent of cuttings that root which are
established one year after planting
D Target plant spacing (1st year): 6.0 feet Desired distance between established
plants after one year
E (43,560 / (D * D)) * A = 303 plants Desired number of established plants
after one growing season
F E * (100/B) * (100/C) = 1,271 cuttings Number of cuttings that need to
be planted
G Cutting Length: 2.5 feet Approximate length of cuttings
H F * G = 3,178 feet Total footage of cuttings to collect for site
I SQRT ((43,560 * A) / F) = 2.9 feet Distance that cuttings must be planted
from each other
Figure 10-56 | Determining the
needed amount of cuttings
This spreadsheet can be used to calculate
the number of cuttings to collect
and how close to plant them on the
project site.
Roadside Revegetation: An Integrated Approach to Establishing Native Plants and Pollinator Habitat
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