Iowa's 2.1 million acres of forest are critical for soil conservation, water quality, wildlife habitat, outdoor recreation and aesthetic pleasure. The forest resource (92%) is largely controlled by private landowners. 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 trees not only increase the quality of life for all residents, but they also provide the livelihood for many. In 1996, the wood products industry in Iowa provided 7,000 jobs, with a combined payroll of $142 million. Private landowners sold $12 million worth of timber; a total of 77.9 million board feet of timber were harvested in the state, and 300 wood products firms, including 71 sawmills, processed the timber. Gross sales of wood products exceeded $850 million.
Recent efforts to develop vegetation management plans for selected state park and recreation areas utilizing Geographic Information System (GIS) mapping was continued in 1997, utilizing DNR Forestry aerial survey work. State park areas where this information is being utilized include: Backbone State Park, Geode State Park, George Wyth State Park, Lacey-Keosauqua State Park, Lake Ahqubi State Park, Palisades-Kepler State Park, Pikes Peak State Park, Prarie Rose State Park, Springbrook State Park, Viking Lake State Park, Waubonsie State Park, Wildcat Den State Park, and Wilson Island State Park. In addition, significant areas of forest such as Loess Hills, Shimek State Forest, Stephens State Forests, Yellow River State Forest, and the Amana colonies were also aerial surveyed during late July to determine the extent of Oak Wilt and other forest health problems.
Oak Wilt continues to be the most serious forest health issue in Iowa. Although all species of oak are susceptible, tree in the red oak group often die within weeks of infection. The fungus moves from tree to tree via root grafts, so the disease often occurs in pockets. New pockets are caused by overland spread of fungal spores by sap-feeding beetles. To prevent establishment of new infection centers, avoid pruning or wounding oaks in the spring and early summer (because the beetles are attracted to the open wounds). Also, spread of established pockets can be stopped by severing root grafts between diseased and healthy trees.
Dutch Elm Disease continued as a serious forest health concern in Iowa in 1997. Much of the re-emergence of DED is due to weather conditions over the past few years that have been favorable to the bark beetles that vector the disease, and due to an increase in the number of 20- 30 year-old American elms that have naturally regenerated in bottomland areas across the state. Lack of sanitation and removal of infected trees over the last few years has contributed to the increase by providing breeding sites for bark beetles, which then carry the fungus to neighboring elms.
Browsing damage by white-tailed deer continued to cause extensive damage to forest and Christmas tree plantations and natural regeneration across the state.
Diplodia Tip Blight, combined with Dothistroma needle blight, continue to damage non native conifer plantations, windbreaks and ornamental planting of Austrian pine, red pine, ponderosa pine and Scotch pine. About 170 acres of Austrian, red, Scotch, and ponderosa pines are affected.
Ash Yellows, a recently discovered disease that causes slow growth and chronic decline of ash, impacted scattered green and white ash in the Eastern and Central portions of Iowa. Urban ash trees are also affected and cooperative studies with ISU and the Forest Service are continuing.
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