BACKUS -- Work has begun to develop a sonogram to test the soundness of wood in standing trees, but Land Commissioner Norm Moody told Cass County commissioners during a tour of county land that it will be a few years before it is perfected.
In the meantime, Cass foresters use information developed from nearly 30 years of monitoring test plots of standing trees to decide when to offer trees on county land for sale to loggers.
The goal is to let trees grow to the maximum number of years to get the maximum sound wood from each tree without waiting until the center of trees begin to rot, Moody said.
Aspen is the predominant tree species on Cass County managed land. Much of it is about 30 years old today. The management goal is to have a wide variety of ages in future years by rotating cutting.
Moody said test plots show aspen can continue to grow to the 45- to 60-year-old range and still maintain sound wood. One significant factor for tree health is whether the trees are growing in the right soil for the tree species, he said.
While about two trees die per year in a one-fifth acre site the department monitors at Deep Portage Conservation Reserve near Hackensack, remaining trees in the plot grow at a fast enough rate to increase overall wood volume on the site every year, he said.
Several trees on the test site are 70 to 80 years old and still show growth when the circumference of their trunks are measured each year. Each tree in the plot is numbered, so can be tracked like banded birds or tagged wildlife.
The last 10 years, the overall wood volume on the site has doubled, according to records the land department maintains.
Foresters have numbered 103 trees in the site. There are 73 aspen, 16 red maples, 11 red oaks and there were one birch and one white pine in 1990. The birch died in 1996 and the pine in 2000. There has been a 14 percent aspen mortality rate, with 10 dying. No maples or oaks have been lost yet.
Moody expects aspen cutting to be accelerated in about 15 years here when trees reach the 45- to-60-year age range. By rotating cutting then, the total tonnage of aspen harvested will increase dramatically as will the future age rotation for timber stands, he predicted.
Cass County Land Commissioner Norm Moody stood by pine trees at Deep Portage Conservation Reserve near Hackensack during a land tour with county commissioners. These trees were grown in containers for four years before being planted. (Photos by Monica Lundquist)
In a clearing at Deep Portage where loggers compacted the soil when they piled logs, Moody said augers were used to loosen soil. Then, the county planted young pines grown first for four years in containers under protected conditions. Valspar herbicide was sprayed on a three-foot circle around each pine to eliminate competition.
Young trees could be planted farther apart than in normal plantations where trees planted are small seedlings and some expected not to survive, Moody said. None of these young trees have been lost. After two years in their outdoor setting, these pines are three to six feet tall.
The only hazard he sees is deer dining on the young pines, though with such a strong head start damage from deer on this plot has been minimal compared with normal tree plantations, Moody said.
In Deerfield Township, land department foresters have been monitoring a 100-year-old stand of white pine where 29 trees were numbered in 1976. Eight were cut in 1985 and one in 2002. This stand will be thinned again this year.
Smaller diameter trees are taken in the thinning to give more space to the larger, hardier trees, Moody said. The larger trees also have a better chance for survival.
When trees are taken from this stand today, each will yield 300 to 400 board feet of sound lumber, he said. Most of it will be clear and knot-free. The stand should survive thinning until it is about 150 years old and the final cutting is done, he predicted.
Young pines are self-seeding beneath this stand.
Cass Land Department has begun a program to accelerate jack pine cutting. These trees grow in isolated pockets, towering above other tree species, Moody said. Foresters have identified their locations with the help of aerial photographs.
The commissioners observed loggers cutting one jack pine stand along the Deerfield Trail between Hackensack and Backus.
They also viewed an access trail over private land the owners have provided to the county under an agreement that the trail be used only for logging access and non-motorized public use to reach county land.
Hikers and horseback riders will be able to use the trail, but the county will install gates to prevent motorized uses.
Commissioners also visited Duffy Lake. The county bought all the shoreline around the lake from a family trust and maintains the area as a wildlife preserve for waterfowl. At times, trumpeter swans use the lake.
Brainerd Dispatch ©2013. All Rights Reserved.