1995 Forest Health Highlights
There are over 2 million acres of commercial forestland in Iowa. This forest resource is largely controlled by private ownership (92%). Iowa's forests are dominated by oak-hickory and sugar maple-basswood in the uplands and silver maple-ash-cottonwood in the bottomlands.
Iowa's woodlands provide over 7,000 jobs in the wood products industry. There are about 300 manufacturers ranging from sawmills and pallet shops to fine furniture manufacturers. Iowas forests are also critical for soil conservation, water quality, wildlife habitat, outdoor recreation and aesthetic pleasures. In the statess 950+ communities, trees are vital to energy conservation, enhancing property values and community appearances.
The Iowa DNR has the responsibility for detecting and monitoring forest health problems within the state. In 1995, aerial sketch mapping surveys were conducted on 238,788 acres of private forested areas located along major rivers, 4 major state forests, 20 state park and recreation areas, to determine the extent of forest health problems. In addition, visual forest health reports are submitted by DNR district foresters and municipal foresters rating severity and location of forest health problems.
Initial results indicate continued tree mortality due to flooding stress on root systems from the 1993 floods. This is in addition to the 11,000 acres of mortality already recorded in 1994. Ground surveys in 1995 revealed increased tree losses from root disease, decay, and secondary insects, in urban park areas flooded in 1993.
Oak wilt continues to be the most serious, persistant, forest health issue in Iowa. Estimates are that an additional 8,000 to 10,000 acres of Iowa's red oak forests were significantly affected by the oak wilt fungus. Severing root grafts between infected and healthy trees, removing recent dead, and preventing wounds are the best means of managing the disease.
Oak decline is caused by drought and other stresses and continues to predispose oaks to two-lined chestnut borer and other secondary insects and pathogens, resulting in scattered mortality.
Noticeable increases in Dutch elm disease reports were due to higher elm bark beetle populations as DED continues to hammer the young and old American Elms across the state.
The invasion of gypsy moth with its destructive potential is always looming. Infestations in nearby states will continue to pose a threat for introducing moth populations. Vigilant monitoring by trapping to identify isolated populations has thus far prevented Iowa forests from becoming generally infested. An eradication treatment was conducted on 52 acres, and all 99 counties in the state were monitored with pheromone traps. Fewer moths (76)were caught this year than in 1994.
Iowas forests continue to face challenges of uncontrolled livestock grazing, high grade logging and increasing urban development. Although the state gained over a 1/2 million acres in woodlands in the last 20 years, timber quality is, for the most part, declining.
In cities and towns across our state, tree removals exceed tree plantings, and tree maintenance such as pruning and tree removal occurs only after natural disasters.
Interest in urban reforestation is high in Iowa, but there is a lack of long term commitment in maintenance and program funding to ensure the long term benefits of trees are achieved.
The Iowa DNR coordinates a cooperative partnership known as the "Iowa Forest Health Task Force" with state and federal agencies, Iowa State University and green industry representatives. The Task Force meets on a semiannual basis to communicate critical forest health issues, coordinate monitoring programs and develop implementation strategies for handling forest health needs. The Task Force conducted its 3rd annual forest health tour in Central and Western Iowa during August, 1995 to investigate forest health applied research needs.
Through a cooperative project with the USDA Forest Service and the Iowa DNR, Iowa State University Department of Plant Pathology coordinated an applied research study of ash yellows, a potentially serious problem of the green and white ash trees common in Iowa's communities. It is generally believed that white ash trees are more susceptible to the disease, and that proper care and tree management will enable infected trees to survive for up to 10 years following the initial observation of symptoms.
Initial results seem to indicate a presence of this pathogen in 18% of tested urban green ash trees. A follow-up study was conducted in 6 communities in Iowa and Wisconsin during 1995 to better determine rate of spread and overall impact. Results are pending. Many other problems are contributing to the decline of urban ash, including abuse and decay.
Iowa DNR foresters provided direct technical assistance to communities that suffered severe natural disasters such as the tornadoes in LeMars, Decorah, and Cresco, Ice Storms in Ottumwa, Albia, Fairfield, Mount Pleasant and Muscatine, and herbicide exposures in Chapin from a chemical plant.
For more information contact William Farris, State Forester
Dept. of Natural Resources
Wallace State Office Building
Des Moines, IA 50319-0034
Forest Health Protection
USDA Forest Service
1992 Folwell Avenue
St. Paul, MN 55108
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