Restoration of oak savannas and prairie remnants is usually
a complicated and expensive process, but real data on costs are hard to find.
From time to time during 20 years of restoration work at Pleasant Valley
Conservancy I was able to record times involved in various tasks. Since most
work involved multiple workers, I have converted the time sheets into
person/hours. Areas restored during the same activities were measured either by
walking the periphery with a Garmin GPS or by GIS using air photos with ArcMap.

The various work activities shown in the summary table need
explaining. Most of the work considered in this post involves removal of woody
vegetation, both trees and shrubs. Removal of herbaceous plants, weeding, is a
different activity and is not presented. Photos are added to present the
context of the restoration activities.

The procedures discussed here have been used on oak savanna
or prairie remnants that are “restorable”. That means that they once were
“good” remnants but had become seriously degraded because of grazing or lack
of fire. They still had some native species and retained small remnant areas.

Basal bark herbicide
treatment

One of the most efficient ways of eliminating woody
vegetation is basal bark treatment with an oil-soluble herbicide that will
penetrate the bark and kill the roots. Since basal bark treatment can be done
any time of the year, it is often done in the winter when many other
restoration tasks cannot be done. At PVC, 100 foot swaths were marked with
flagging tape and workers move along these swaths, treating any target species.
The treated plants died during the next growing season and the dead plants were
left in place. In a year or two they fell over and slowly decomposed. This works
best for scattered plants.

Cut and treat

Denser populations of brush such as honeysuckle, buckthorn,
or brambles, were cut with motorized brush cutters, followed by cut stem
treatment with herbicide. Depending on the species cut, glyphosate or triclopyr
was used to treat the cut stems. This procedure involved a team of people, one
operating the brush cutter and three or four following with herbicide spray
bottles. This procedure was used primarily on infestations of smaller shrub heights
(2-4 feet), and the cut brush was just left on the ground to burn up at the
next fire.

Tree work

Many restorations involved the removal of invasive trees
such as walnut, elm, cherry, and box elder as well as brush. Often these trees were
10-20 inches in diameter and an experienced crew (contractor) was needed. If
the trees were smaller, so that removal was less technical, an experienced
chain saw operator could work with a group of less experienced workers. Tree work
requires much more time because brush piles must be built, and the cut logs must
be removed from the site.

Foliar spray
(reprouts after a burn)

A very efficient method of removing brush is to burn the
unit (either spring or fall). A properly conducted burn will top-kill the
shrubs. In late spring or early summer new shoots will appear and can be
sprayed with an herbicide such as aqueous triclopyr. This is a very effective
procedure and is less time-consuming than others. There is no cut wood to deal
with, and the sprayed plant is usually eradicated.

Foliar spray (fall)

In the fall, buckthorn and honeysuckle retain their green
leaves long after all the native vegetation has senesced. Although the timing
is variable from year to year, these plants can usually be killed by a foliar
spray such as glyphosate or triclopyr. Remember: if it is green, it will be
killed. Senesced plants (brown) will not take up herbicide. Glyphosate is
preferred because there is no soil residue.

Photos

Examples of the techniques  used are given at the end of this post.

The Table

The table is arranged in two ways

I used hours per acre to express costs because hourly rates vary widely,. However, I have added a column assuming
$25 per hour.

$$ per acre based on $25 hourly rate; other rates are
possible, or none, if the work is done by volunteers.

Discussion

Basal bark is one
of the most economical methods of brush control. However, the dead brush is
left standing, and one must wait a year or two for the dead stems to disappear.
However, it could be used as a preamble to a major tree cutting operation. If
it was known that a lot of trees were going to be cut in a unit in a year or
two, it would be efficient to basal bark all the woody vegetation. The dead
wood could then be used as the base of the brush piles that would be made from
the smaller branches of cut trees.

Foliar spray of
resprouts after burns is another economical method of brush control. By
spraying the resprouts before they get big, one is eradicating the plant and
preventing it from getting larger. The principal problem is timing. Not all
plants resprout simultaneously, so that it is necessary to canvas each area at
least twice, and preferably three times. Also, spraying usually must be done in
May when herbaceous weed control is also underway.

 

Cutting and treating in winter. Light snow is helpful in keeping track of where the brush cutter has been.