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Draft Cottonwood Management Plan (CMP)/Programmatic Environmental Assessment (EA)
Proposed Implementation of a Cottonwood Management Plan along Six Priority Segments of the Missouri River
The plains cottonwood (Populus deltoides) was once the dominant floodplain vegetation in the Missouri River ecosystem. Natural cottonwood regeneration has largely ceased along the Missouri River following the construction of the Missouri River Mainstem Reservoir System and Bank Stabilization and Navigation Project. The reduction in the number of young cottonwoods to replace older cottonwoods concerns biologists because a variety of plant and wildlife species, including some protected species, are associated with cottonwoods. Bald eagles (Haliaeetus leucocephalus) and other native wildlife species depend on the adjacent cottonwood forest for nesting, roosting, and wintering habitat along the Missouri River. The degradation of the cottonwood forests will likely continue in the future and result in additional impacts to these native species.
The Proposed Action for this project includes the implementation of a Cottonwood Management Plan (CMP). The purpose of the CMP is to guide management actions along the Missouri River to protect and restore cottonwood forests in the six priority river segments identified by the U.S. Fish and Wildlife Service, to the extent possible, the natural range of cottonwoods. The CMP suggests ways the Corps can protect cottonwood stands as well as establish new cottonwood stands to keep the riparian habitat along the river a viable forest community.
The Draft CMP/EA discusses proposed management techniques. It also discusses the environmental consequences to the physical, natural,
cultural, and human resources along the Missouri River as a result of the implementation of the CMP. The CMP/EA is now available for
public review. An electronic version of the document can be found below or under MRRP Documents,
Recent Articles/Reports.
Written comments on the CMP/EA may be submitted to: Suzie Boltz, EA Engineering, 15 Loveton Circle, Sparks, MD 21152.
Please send comments by May 23, 2010.
Draft Cottonwood Management Plan (CMP)/Programmatic Environmental Assessment (EA)
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Issue
Settlement, property and farmland development, and dam construction on the Missouri River have reduced the size of the cottonwood forest, which provides important roosting and nesting habitat for many bird species. Songbirds such as American goldfinches, yellow warblers, and ovenbirds feed and nest in young cottonwood forests. Bird species often found in older cottonwood forests include Northern orioles, mourning doves, warbling vireos, and Eastern kingbirds. Woodpeckers and black-capped chickadees build their nests inside old or dead cottonwood trees. In the Great Plains, bald eagles nest almost exclusively in the strong branches of a cottonwood tree. Most regional tree species are too small to support a bald eagle nest, which can span up to nine feet wide and weigh up to a ton.
Biologists are concerned about the future of cottonwood forests along the Missouri River and the bird species that depend on them. Most of the cottonwoods along the upper part of the river began growing before the dams were built. The river's dams have eliminated the natural flooding regime and extensively reduced the creation of areas of bare, moist soil, which provide ideal conditions for new cottonwoods to grow.
Without a natural flooding regime or extensive cottonwood planting efforts, biologists predict cottonwoods will eventually be replaced by trees such as green ash and Russian olive. These smaller trees support a lower diversity of bird species than tall cottonwoods. Studies have shown that cottonwood woodlands support more cavity nesting birds (i.e., woodpeckers) than green ash, juniper, or bur oak woodlands. Cottonwood woodlands also have a greater diversity of bird species than shelterbelt plantings, which are rows of trees planted near farmsteads.
Birds are not the only part of the Missouri River ecosystem that would be affected by the loss of cottonwoods. Historically, floods scoured older cottonwood trees into the river and backwaters, where the trees sheltered fish and attracted fish prey such as macroinvertebrates. The Corps often places cottonwoods in its backwater restoration projects to mimic historic conditions. Smaller trees would be less valuable as fish habitat. Cottonwoods also provide erosion control with their extensive root system, stabilizing riverbanks better than trees with smaller root systems.
Cottonwood Management Plan
The purpose of the Cottonwood Habitat Program is to develop a cottonwood management plan. The goal of the plan is to be a living document that preserves, creates, or enhances cottonwood habitat along the Missouri River.
To develop the cottonwood management plan, the Corps is developing a landscape-level cottonwood riparian community model to assess habitat quality along six priority reaches identified by the U.S. Fish and Wildlife Service. The model will incorporate biotic (presence of cottonwood age classes, cottonwood age class distribution, number of species that are indicators of cottonwood communities, number of invasive species, percent cover of shrubs), water (depth to groundwater, frequency of flooding, rate at which groundwater recedes, height above mean river stage), and landscape (distance to nearest cottonwood patch and adjacent land use) variables. A critical component of the cottonwood riparian community model is the integration of bald eagle habitat and cottonwood regeneration concerns as it relates to compliance with the Biological Opinion on the Missouri River. The Biological Opinion requires that the Corps fulfill three reasonable and prudent measures: map the health of the remaining cottonwood forests, create a cottonwood regeneration plan, and ensure that no more than 10 percent of the cottonwood forest that is suitable bald eagle habitat is lost as eagle habitat.
Dr. Carter Johnson, from South Dakota State University, and Dr. Mark Dixon of the University of South Dakota (USD), are organizing, conducting, analyzing, and summarizing vegetation sampling along the two reaches of the Missouri National Recreational River (MNRR), along with five other Missouri River reaches in Montana, North Dakota, South Dakota, Nebraska, and Missouri, Carter's group includes researchers, professors, and graduate students from the USD, Benedictine College, and U.S. Geological Survey.
During the summer of 2007, the USD team sampled overstory and understory vegetation on 17 forest stands within the 39-mile stretch of the MNRR between Fort Randall Dam and the Niobrara River, and 34 stands within segment 10, the 59-mile stretch of the MNRR between Gavins Point Dam and Ponca, Nebraska. The USD team also finished draft 1892 land cover Geographical Information System (GIS) coverage for segments 8 and 10. The team finished draft 2006 land cover GIS coverage for both segments. They completed a draft map depicting cottonwood age classes within floodplain on segment 10, using overlays of photographs or maps from 1892, 1956, 1980s, 1997 and 2006. The team began ground-truthing vegetation and age class classification on segment 10, including separation of cottonwood vs. non-cottonwood floodplain forest. They began the development of species lists and collection of voucher specimens.
Data collection for the cottonwood model will be finished in 2009. The model is scheduled to be finalized in 2010 and will be used in the implementation of the cottonwood management plan, which is also expected to be finished in 2010.
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