After Harvesting, Be Prepared for the Invaders
By Maxwell McCormack
The poplar wars – ”popple” if you prefer – were underway by late July on a part of our woodlot harvested last winter. Where there had been 10 to 12 poplars per acre in a mixed softwood stand, by early August here were thousands per acre. The merchantable trees had been cut when root reserves were high. By August they were attacking aggressively, with root sprouts growing over a foot in height each week. Before the end of the month they were six to eight feet tall, with some root collars almost an inch in diameter. “That’s real productivity,” observed one forester friend.
Fresh-cut stump treatments would have been nice as a proactive sprout reduction treatment. However, the timing of the harvest was dictated by contractor scheduling, and it took place during the coldest part of the winter, with intermittent snow covering the stumps. The winter timing was great for harvesting conditions, but it favored the poplar surge.
The onslaught of sprouts got my attention (See photo below). You could almost watch them grow. Clipping the sprouts would have been counterproductive. The only practical approach with assured effectiveness was to employ herbicide, especially since the site had been planted with white pine seedlings.
“Why aren’t you spraying?’ asked visitors in early August. “Patience,” I replied. In order to deal with the massive poplar root systems, I needed as much leaf surface target as possible in order to maximize active ingredient uptake. The inquiry continued, “I suppose you’ll use the old standby Roundup (glyphosate) to treat the sprouts?” I explained that I planned to use Garlon (triclopyr) to maintain some of the grassy ground cover and minimize risk of injury to the planted pines. Even slightly elevated rates of glyphosate can injure white pines.
As this example suggests, there are many factors to consider when formulating prescriptions for management of competing vegetation. And we haven’t touched on rates, volumes, carriers, adjuvants, and spray patterns. Of course, such challenges are not limited to poplars. The culprits vary from region to region and from site to site. But quality forest sites will consistently support dynamic competing vegetation. It’s important for woodlot owners to be able to accurately determine the species that pose the greatest threats to potential crop trees and understand their growth patterns.
The list of species is extensive. Following, are 13 selected tormentors that can occur on disturbed (harvested) sites by common name, scientific name, and additional common names. Because of overlapping common names, particularly where there is regional parlance or colloquial expression, the scientific name clarifies species identity.
Bigtooth aspen; Populus grandidentata Michx.; popple, aspen, largetooth aspen.
Quaking aspen; Populus tremuloides Michx.; popple, aspen, trembling aspen, golden aspen.
Beech; Fagus grandifolia Ehrh.; American beech.
Red maple; Acer rubrum L.; soft maple, white maple, swamp maple, Maritime maple.
Striped maple; Acer pensylvanica L.f.; moosewood, moose maple.
Black cherry; Prunus serotina Ehrh.; wild cherry, rum cherry.
Pin cherry; Prunus pensylvanicum L.; fire cherry, bird cherry.
Raspberry; Rubus idaeus L.; red raspberry, brambles.
Blackberry; Rubus allegheniensis Porter; common blackberry, brambles.
American burnweed; Erechtites hieraciifolia( L.)Raf. Ex DC; fireweed, pilewort.
Fireweed; Epilobium angustifolium (L.) Scop.
Field bindweed; Convolvulus arvensis L.; bindweed
Wild buckwheat; Polygonum convolvulus L.; bindweed.
Aspens, first on the list, are prolific root sprouters; bigtooth is the best of the two to retain, but browsing deer select for bigtooth over quaking. We know beech (No. 3) is a prolific sprouter from stumps and roots; treat it as soon as possible in any case. Red maple (No. 4) is a vigorous stump sprouter; though readily suppressed with foliar sprays, timely stump treatments can be a good approach. Striped maple (No. 5) is no big deal in my mind; timely foliar treatment is effective. Nos. 6 and 7, the cherries can regenerate profusely from banks of buried seeds; black cherry also sprouts from roots and stumps. In many cases, P. serotina can be managed for individual crop trees in a developing stand. P. pensyvanicum, on the other hand, can become an early challenging competitor; this is a good example of the value of seedling species determination.
Brambles (Nos. 8 and 9), a vague term, are usually composed of raspberry (See photo, page 8). It’s deceptive during the first year or two following disturbance, but then it comes on aggressively, obscuring established tree regeneration. On favorable sites raspberry dominance can last for over 20 years. Identification of blackberry in a bramble patch likely means a more difficult management problem. Both species of Rubus are strongly founded on long-term; 20 to 60 years or more banking of buried seed.
American burnweed (No.10, and see photo) virtually explodes on recently disturbed sites. Though an annual plant, its relatively large, heavy biomass can effectively engulf small tree seedlings. Sometimes this species is referred to as “fireweed.” However, fireweed (No. 11) of the genus Epilobium is more commonly considered to be the true “fireweed.”
Finally, the group of spreading ground plants usually referred to as “bindweed” include field bindweed (No. 12) and wild buckwheat (No. 13, and see photo below). This is another point of confusion since wild buckwheat is often referred to as bindweed. Field bindweed is a perennial, wild buckwheat is an annual. Each develops an aggressive vine-type habit that can smother tree seedlings.
There are many other competing species and woodlot owners can be sure that, once appropriate tree species have been established on productive sites, suppression of competing vegetation is one of the most significant practices you can apply to foster robust crop trees.
Maine Woodland Owners member Max McCormack is research professor emeritus at the University of Maine. E-mail him at: mlm2@uninets.net
One month growth of American burnweed following a winter harvest. Range pole stripes are each one foot.
Wild buckwheat spreading across the site of a winter harvest in a mixed hardwood/softwood stand.