CONTACT INFORMATION:
Team Leader: Catherine Parks (cparks01@fs.fed.us),
Nan Vance (nvance@fs.fed.us)
Phone: 541-962-6531 (Parks), 541 750-7302 (Vance)
Research or Development Rationale:
In recent decades, non-native invasive plant species have increasingly supplanted
native species on both disturbed and undisturbed sites in the interior Pacific
Northwest. As non-native plants become more dominant in forest, grassland, and
riparian plant communities, competitive simplification of native plant communities
may result in loss of biodiversity, alteration of ecosystem function, and shifts
in trajectories of plant succession. Although it is widely accepted that timber
harvest and fire, both wild and prescribed, have direct and indirect influence
on the establishment and persistence on non-native invasive plants, limited
research has been conducted to test or support this concept. The knowledge base
for management of non-native invasive plant species is largely derived from
agricultural research, where techniques and treatments have been applied under
controlled field conditions. Agricultural approaches can seldom be utilized
in forests and rangelands. In addition, knowledge about the basic biology and
ecology of many invasive plants is lacking, thus hampering effective and long-term
control strategies.
The interior PNW is characterized by landscapes of mixed forests intergrading
with temperate dry shrub steppe that have evolved under frequent fire intervals.
These fires of varying intensity have resulted in a mosaic of plant communities,
composed of species with different ecological amplitudes and adaptations to
fire. These native communities, which generally undergo rapid post-fire recovery
provide vegetative cover, and contribute to stability of montane slopes, and
reduction of soil erosion potential. As a consequence of the transitional nature
of this region, large, stand replacing fires that destroy canopy cover may convert
forest types to more open grass types and barrens that favor aggressive exotic
species usually associated with the dry steppe. It is not known if the displacement
of native species by exotics increases the potential for erosion because exotics
are less suitable for stabilization of soils. The specific effects of fire and
fuel treatments, such as thinning, that cause changes in species dominance in
these shifting mosaics are not well understood.
To add to current knowledge, we propose research with the following broad goals: 1) increasing knowledge on the basic ecology of selected invasive species and native forbs and grasses and their interaction with fire and disturbance, and 2) developing post-fire rehabilitation and restoration methods.
Research and Development Approach:
User needs/science gaps addressed: We will directly address the following
science gaps identified under NFP Research Priority Biii: guidelines and practices
for reestablishing native species and excluding invasive exotic plants on burned
areas in long-term recovery of burned areas; conditions and requirements for
developing seed sources of native plants; and methods for assessing, monitoring,
and modeling post-fire vegetation recovery and plant invasions. Results will
also contribute to science gaps identified under Research Priority Bii, particularly
knowledge about the effects of wildfire and prescribed fire on habitat.
Managers addressing post-fire rehabilitation are giving high priority to achieving
sufficient cover of native forbs, grasses and shrubs for long-term slope stability
in addition to short term BAER treatments. Where evaluation indicates that native
plant communities have not recovered, the reasons are ecologically complex.
One hypothesis is that favorable conditions for the colonization and spread
of invasive exotics confound the natural recovery of native plant communities.
Increased cover and diversity of healthy plant communities may confer resistance
to exotic invasions, but studies have been inconclusive. The interaction of
invasive species with the their native plant neighbors needs to be studied if
weed resistant plant communities are to be developed or maintained. Effective
restoration requires identifying species that have characteristics of resistance
to invasive exotic plants as well as soil stabilization properties. We plan
to determine if increasing the cover of these species accomplishes both objectives.
Few studies have been conducted on responses of invasive plant species to
wildfire and fuel reduction techniques. In forested ecosystems, considerable
research has been conducted on fuels management and applied silvicultural problems;
however, relatively few studies have addressed the effects of forest management
on understory composition and diversity. In open grasslands and riparian areas
the interest in increasing the diversity of native species and in building weed
resistant plant communities is a high priority with restoration planners and
commercial plant and seed suppliers. Basic information on plant species and
community responses to wildfire and fuel reduction treatments (thinning, prescribed
burning) are essential to resource managers in the assessment of ecological
condition and trends, or for development of sound post-fire management strategies
that enhance wildlife habitat and other components of biological diversity.
The proposed research seeks to address these science gaps through:
Scientific Approach:
This research combines observational, experimental, and retrospective approaches.
Observational: We propose to characterize basic plant population biology
and demography for the invasive perennial plant species, sulfur cinquefoil.
The increase of sulfur cinquefoil in interior PNW has alerted managers to the
urgent need for management recommendations, as well as basic plant biology information
necessary to develop effective management strategies. Measurements will include
seed production, dispersal, and seedling recruitment, and will be related to
age of stand, and site variables (elevation, slope, aspect, soil type, plant
community, land use, disturbance history). We will determine population age
structure through examination of annual rings in the taproots using methods
that have recently been developed in Europe (referred to 'herb-chronology'),
and correlate age of populations and expansion patterns to wildfire and other
disturbance events. We will also study the reproductive ecology to define its
reproductive niche. The insect pollinator assemblage will be referenced, targeting
infested areas where sulfur cinquefoil co-occurs with populations of native
cinquefoil species.
Using GIS maps, aerial photographs, and plot data to examine dry forest/open land mosaic in the region, forest and open plant community types perpetuated by wildfire and topography will be identified and used to stratify the most commonly occurring native plant communities. Plant communities will be sampled in a replicated design for data that includes fire history and effect as well as other environmental attributes used to characterize the ecological land unit. This basic analysis will be used in the experimental studies to test suites of native plant species most suitable for post-fire restoration, weed resistance, and slope stabilization in forest, or open systems created by fire frequency and size.
Experimental: Effects of prescribed burning on the growth, density,
seed bank dynamics, and seedling recruitment of invasive species, particularly
sulfur cinquefoil and yellow star thistle, will be examined in experimental
plots in at least two different study locations in northeast Oregon and one
in west central Idaho. Responses of associated native species will also be monitored
in treated plots. Rehabilitation treatments will include herbicide application
and seeding with native grasses and forbs.
To evaluate native and exotic species for slope stability potential in the
field we will assess ground cover development following wild fire in erosion
susceptible sites. On runoff plots, life forms and life cycles of dominant plant
species and soil surface conditions will be characterized. Experiments will
include seeding plots (bare mineral soil) at different densities using non-native
grasses, native plant species, and selected exotic invasive species. Summer
precipitation, runoff and sedimentation will be measured. Temporal and spatial
changes in plant species dominance will also be evaluated.
To evaluate the effects of fuel reduction treatments on invasive plant species,
forest understory, and seed production of native species, we propose to augment
ongoing research at three Fire and Fire Surrogate Study sites (Hungry Bob, near
Enterprise, Oregon; Mission Creek, near Wenatchee, Washington, and Lubrecht
Forest near Missoula, Montana). We will sample forest understory within the
sites more intensively, and analyze baseline and vegetation changes through
time (occurrence, abundance, native/exotic ratios) to test differences in occurrence
and abundance of invasive species among treatments and between sites.
We also propose to measure seed production of dominant, native understory plant species of major habitat types on these three Fire and Fire Surrogate study sites. Seed production on thinned, burned and thinned and burned, and a control site will be collected for 3-5 years following fire or fire surrogate treatment. Native shrub, grass, and forb species will be evaluated for germination success and yield in agricultural multiplier environments. Seeds will then be re-introduced into different vegetation types. With this approach we expect to identify native indicator species that would be useful for short and long-term post fire rehabilitation efforts.
Retrospective: We will utilize the existing database from the USFS Ecology Program to select permanent plot locations that have been recently burned (within the last five years). Plot-level data will be analyzed for responses of vegetation to fire, particularly increased occurrence and expansion of invasive plant species following wildfire in forest, grassland, and riparian communities.
Development and technology transfer approach: We propose a workshop on the state of native plant seed source and availability and seed handling technology, and a regional infrastructure for R & D of native seed production and use. This provides a framework for studies that investigate which species are best suited for rehabilitation, i.e. which have the greatest potential to be used for seeding open, freshly disturbed areas, and which seed mixes are most compatible with early seral and established native plant communities over different soil types or conditions. This research, throughout its entirety, will be conducted with a broad range of university researchers, land owners, and land managers assuring the results are immediately available.
Description of products and how they will be used:
Products of this research will contribute fundamental knowledge about the biology
and ecology of certain invasive species and native plants, their role and behavior
in post-fire succession, their control and treatment in rehabilitation efforts,
and interactions among species responses, fire, fuel reduction treatments. Interim
results will be presented at regional and national scientific meetings, and
local and regional workshops, and published through proceedings, newsletters,
and PNW Station Research Notes. We anticipate the preparation and publication
of a USFS General Technical Report (GTR) and journal article describing the
techniques and preliminary findings of our 'herb chronology' research within
the first two years of the project. Simple keys to distinguish invasive plant
species from similar native congeners at different life stages will be published
as user tools to assist in early, definitive detection of invasive species in
assessment efforts. Final products targeted to the scientific community will
be published as refereed journal articles, PNW Station Research Reports and/or
GTRs; final products targeted to managerial user groups will be published as
one or more GTRs, with guidelines and suggested protocols for rehabilitation
efforts that control for the expansion of invasive plant species. Because most
of the invasive species of concern are widespread throughout the U.S., we anticipate
that the scientific results and guidelines will be used by ecologists and resource
managers across multiple regions. An additional contribution of the project
will be the establishment of study areas that can be repeatedly monitored over
time for longer-term successional changes.
Research partners, roles and commitments: Oregon State University (through Steve Radosevich, Dept. of Forest Science) will partially support 1 post doctorate research associate and 1 graduate student. Oregon Department of Fish and Wildlife will provide available equipment/personnel to apply treatments on the Wildlife Management Areas.
Ed DePuit, PNW Station, Wenatchee Forestry Sciences Lab - collaboration on
rehabilitation treatments.
Mike McInnis, Eastern Oregon University; plant/range/weed ecology; collaboration
on weed biology research, interactions of invasive and native plant species;
Linda Wilson, University of Idaho; modeling population biology, demography,
and projected expansion.
Charles Johnson, NFS Area Ecologist,- plant ecology, synthesis of existing databases
on natives.
Marty Vavra, Eastern Oregon Agricultural Research Center, ungulate/range ecology.
Rocky Mountain Elk Foundation; ungulate ecology; rehabilitation of winter range
John Kie, LaGrande Lab, PNW Research Station; wildlife ecology
Dr. Peter Bernhardt, Research Fellow, Missouri Botanical Gardens, St. Louis
(joint venture) pollination ecology of sulfur cinquefoil
NRCS Plant Materials Center, Corvallis, Oregon, collaboration in seed and cultivation
of plant material
JH Stone Nursery, Central Point, Oregon, collaboration in producing plant material.
Fritz Sweingruber, Swiss Federal Research Institute for Forests, Birmensdorf,
Switzerland
Potential Users:
Center for Invasive Plant Management, Montana State University, Bozeman, Montana
National Forest Systems in R6, R4, and R1, USDI Bureau of Land Management
The Nature Conservancy, Private Land Owners, Commercial native plant and seed
suppliers in the region.
Forest and Weed Scientists, State and Private Foresters
Oregon, Washington, and Idaho Departments of Agriculture, Noxious Weed Programs
Tri-County Weed Management Area, northeast Oregon
Regional and forest botanists and plant ecologists in R1,R4, and R6
Linkages and integration: The proposed research is described as a stand-alone project. However, if funded, we intend to integrate research with existing (and proposed) projects across the West.
Co-investigators: Dana Perkins, Research Ecologist, PNW Station, La Grande,
and Kate Dwire, Research Riparian Ecologist, RM Station, Laramie.
Lead Research Work Unit: Managing Natural Disturbance Team, MDR Program, La Grande, and Biology and Culture of Forest Plants Team, RMP Program, Corvallis, Oregon.
Lead Research Station: PNW Research Station