Management of plains cottonwood at Theodore Roosevelt National Park, North Dakota

Natural Resource Report NPS/THRO/NRR—2017/1395
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Abstract

Establishment of cottonwood trees is driven by flood-induced channel migration, which provides the new surfaces necessary for successful germination and survival. Along the Little Missouri River the largest floods typically result from snowmelt in March or April. Seed release occurs in early summer, and seedlings usually germinate in moist, open locations on point bars at relatively low elevations above the channel. Subsequent channel migration allows seedlings to mature by protecting them from scour in floods and ice jams. Management actions that decrease channel movement will reduce cottonwood reproduction. Growth and survival of cottonwood trees are strongly decreased by extreme low flows. As a result, management activities that decrease low flows could strongly reduce growth or kill trees. Surface-flow diversions are less damaging to trees if carried out during the spring when flows are relatively high. Herbicide application by helicopter to control leafy spurge appears to have inadvertently damaged or killed about 25% of the cottonwood forest along the Little Missouri River in the South Unit. Area of adult trees sprayed has been reduced since 2007 to limit this damage. It is not known whether spraying of cottonwood seedlings on unforested point bars is reducing cottonwood reproduction in the South Unit. Warmer temperatures since 1976 have reduced flood peaks and the ice jamming that magnifies those peaks; as a result channel movement, cottonwood establishment and cottonwood growth have decreased. Increasing temperatures associated with global climate change could continue this trend.

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Additional publication details

Publication type Report
Publication Subtype Other Government Series
Title Management of plains cottonwood at Theodore Roosevelt National Park, North Dakota
Series title Natural Resource Report
Series number NPS/THRO/NRR—2017/1395
Year Published 2017
Language English
Publisher National Park Service
Publisher location Fort Collins, CO
Contributing office(s) Fort Collins Science Center
Description vii, 34 p.
Country United States
State Montana, North Dakota, South Dakota, Wyoming
Other Geospatial Little Missouri River