The Missouri River flows 2,540 miles from its headwaters in southwestern Montana to its confluence with the Mississippi River north of St. Louis. The watershed covers more than 529,000 square miles in portions of ten states, supporting a multitude of uses including agriculture, wildlife habitat, drinking water, industry, and power generation.
In 2005, the Missouri River Watershed Coalition (MRWC) was organized to help protect the watershed from invasive plants including saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia). The mission of the Coalition is to maintain productive, biologically diverse riparian habitat to meet the economic and ecological needs of the Missouri River Watershed region.
The MRWC teamed up with the Center for Invasive Species Management (CISM) in 2010 and received a $1 million Conservation Innovation Grant (CIG) from the USDA Natural Resource Conservation Service, and additional state matches of $750,000 from Montana and $250,000 from Wyoming.
Scott Bockness, CIG Project Field Leader for the Coalition is tasked with developing solutions to regional invasive plant issues within the watershed through this riparian investigation. “The objective of this project is to investigate methods to help mitigate the impacts of Russian olive and saltcedar and explore their potential use as bioenergy products,” Bockness explains. “We believe our results will help producers and land managers with Russian olive and saltcedar management projects and serve as a model for other large-scale invasive plant projects in the West.”
Management Study Areas
Russian olive- and saltcedar-infested sites were selected in six locations within three of the Missouri River Watershed Coalition states (Table 1). Sites include both regulated (dammed) and unregulated (free flowing) river watersheds with different saltcedar and Russian olive invasion patterns in terms of age, infestation size and density. Land use on the study areas range from livestock production to conservation areas.
“Our objective for the field studies is to determine which management methods provide the most effective control of saltcedar and Russian olive, in addition to evaluating the plant community response to herbicide treatments,” explains Bockness.
Herbicide treatments on Russian olive and saltcedar included Garlon® 4 Ultra as a foliar application to young trees, and as a basal cut stump or basal bark treatment depending on the size of the target tree. Herbicides were applied in fall and early winter of 2012 at all sites except Lovell, Wyoming, which was treated spring 2013 (Table 1). Data collected at the Wyoming site will compare basal cut stump herbicide treatments to mastication and herbicide treatment that is part of an on-going Coordinated Resource Management Project.
Long-term monitoring data collected pre- and post-treatment from the study includes cover and relative abundance of Russian olive and saltcedar, desirable native and non-native species, and other invasive species that may colonize the site after treatment. Bockness explains, “These data will allow us to measure plant community changes over time for each treatment method under different land uses and hydrologic conditions. We will also be able to evaluate the efficacy of basal bark and basal cut stump treatments for controlling saltcedar and Russian olive.”
Local, state, and federal agencies including the NRCS have committed resources to mitigating the impacts of saltcedar and Russian olive throughout the region. Work conducted in the watershed prior to 2012 show excellent efficacy with Garlon® 4 Ultra on both Russian olive and saltcedar, and results from the current study will help land managers adapt conservation practices to improve long-term control of these invasive plants and improve ecosystem function.
Exploring the feasibility of converting invasive Russian olive and saltcedar to fuel is a key component of the project. Bockness explains, “We have at least one million acres infested with these invasive trees in the Missouri River Basin, and each acre produces from 5 to 10 tons of wood biomass that could be a great source of bioenergy. Current management includes cutting, stockpiling and burning the trees since other economical alternatives haven’t been explored.”
Russian olive and saltcedar samples were collected in July and August 2011 from five sites in Montana and Wyoming. Tests were conducted on the samples to determine British Thermal Unit (BTU) levels generated per pound of material, as well as ash content, volatile matter content, and moisture content. Test results were compared to data from forestry species traditionally used in bioenergy applications (Table 2).
Comparisons of the data indicate that while the BTU levels of both Russian olive and saltcedar are relatively close to those of forest materials, the ash content level of saltcedar is considerably higher than the desired levels for use in commercial wood pellet markets. Unlike other forest residues, these shrub-like invasive species require special (and more expensive) treatments to harvest, making them an expensive fuel source compared with natural gas, coal or forest fuels.
“The ash content is too high for making a high value residential wood pellet, but there may be a potential to supply facility-scale heating boilers with biomass,” says Bockness. “One of our biggest problems is the cost of transporting biomass; we need a facility within about 100 miles of our removal site to be economically feasible.”
The University of Nebraska-Lincoln and the Center for Invasive Species Management at Montana State University are working together to pursue funding for assessing the feasibility of installing biomass facilities in local schools or hospitals and integrating Russian olive and saltcedar removal with other fuel reduction projects on forest lands.
The MRWC project has united university, county, state, and federal agencies in a collaborative effort to manage invasive plants over a wide geographic area encompassing seven of the ten watershed states. “We believe that results from this project will help develop science-based conservation approaches for managing Russian olive and saltcedar in the Missouri River Watershed,” says Bockness. “Increased knowledge related to the removal of invasive species and the vegetative response to the treatments will be critical to understanding secondary weed invasion and to facilitate ecosystem recovery methods. In addition, determining the feasibility of biomass generated from invasive species could be an innovative catalyst in supporting regional woody biomass alternative energy program developments.”
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Active ingredients for herbicide products mentioned in this article: Garlon 4 Ultra (triclopyr).