Many riparian zones in the northern Rockies are undergoing succession to coniferous species in the absence of flooding and fire. Changes in riparian plant species composition have altered ecosystem dynamics, reducing the system's potential for maintaining a variety of species associated with riparian zones and increasing risk of uncharacteristically severe fire.
Research is needed to define past and current conditions and frequencies of fire, determine ecosystem responses and conditions resulting from recent burns in riparian areas, and evaluate direct fire effects (e.g., from fire in riparian zones themselves) and indirect effects (e.g., from fires in uplands).
- What were the historic conditions, including historic fire frequency patterns, of riparian zones, and how do they compare with current riparian conditions and fire patterns?
- How do contemporary effects of fire in riparian zones vary by altitude, plant species composition (deciduous vs. coniferous, shrubs versus trees, natives vs. exotics), and surrounding vegetation (e.g., coniferous versus grassland uplands)?
- How can resulting data on historic fire patterns and current fire conditions and effects be used to restore riparian zones to conditions that support riparian species and appropriate fire intervals and to reduce fire risk?
Research and development approach
The need for information on riparian disturbance processes and vegetation patterns extends throughout the Region and ultimately should be provided for various stream types and geophysical settings.
In 2001, we performed a pilot study on the Bitterroot NF, trying out some practical approaches to stratifying riparian areas, gathering data, and making sense of the information.
We chose three biophysically similar drainages that varied in time-since-burning, and related this disturbance history to riparian plant community composition and structure, and to stream characteristics.
Based on the results, we modified our sampling design.
In 2002 and beyond, we will continue to work on the Bitterroot NF and other forests in the Western Montana Planning Zone.
Our ultimate goal is to quantify the linkages between disturbance history in the uplands and riparian zones of headwater drainages designated as endangered salmonid habitat to stream characteristics and ultimately, fish habitat.
This project will provide fundamental ecological information that is currently lacking for Rocky Mountain ecosystems and support Forest Plan revisions and long term management direction.
Numerous wildfires burned in riparian zones of western Montana in 2000, presenting opportunities to evaluate fire effects on a suite of riparian types.
Geographic Information Systems databases of topography, stand inventories, treatment history, fire history, and ecological information have been compiled for Montana sites to stratify and choose potential study areas.
The first steps will include:
- Use historic or reference reach information to describe natural vegetation patterns and channel structure for each riparian type.
- Stratify stream reaches by type (using Rosgen or Montgomery-Buffington classifications) and basin area.
- Determine a set of potential field sites, burned and unburned for as many strata as feasible.
- Randomly sample a replicated set of field sites to evaluate vegetation and stream channel characteristics, disturbance history and fire effects, and fish community structure.
- Define the hydrologic and physical processes that operate in natural systems for each category. Subsequently we will describe how vegetation patterns, riparian processes, and fish communities have changed relative to historic conditions, and what the impact of fires at various severities was on the riparian systems, and establish an efficient methodology for gathering this type of riparian information that could be used throughout the Region.
Research results will supply guidance for restoration efforts in riparian zones to conditions suitable for maintaining riparian plant and animal species, with appropriate fire frequency intervals, and for averting catastrophic fire damage in riparian zones.
Outcomes or products
- First year: Descriptions of natural vegetation and stream reaches and stream stratifications; field sites selected.
- Second year: Publications and presentations describing riparian zones from existing databases; Riparian zone field sampling and characterization.
- Three to Five years out: Publications and presentations describing field and database comparisons of riparian zones; definitions of hydrologic and physical processes operating in natural streams; descriptions of vegetation patterns, riparian processes, and fish communities as a function of landscape and fire processes; workshops for managers describing efficient methodologies for gathering this type of information.
Dr. Finch is working in the southern Rockies, and is stationed at the RMRS laboratory in Albuquerque, NM.