Introduction

The Nevada Bureau of Land Management's Office of Fire and Aviation started exploring live fuel moisture sampling procedures in 1980 through a fire effects/fire behavior study.  After becoming more experienced with the significance of live fuel moisture and the resulting fire behavior seen at various fuel moisture levels, the Nevada State Office began tracking foliar moisture levels in sagebrush year-round in the Reno, Nevada, area.  In 1983 following a fire fatality investigation in Carson City, Nevada recommendations were made identifying the need to alert fire fighting personnel of potential fire behavior problems.  Many fire managers questioned the accuracy of NFDRS at the time.  The Great Basin Live Fuel Moisture project was implemented in earnest after consulting with the Missoula Fire Lab and University of Colorado.  The attached Fire Behavior Tactics page was developed working with the Missoula Fire Lab after a Nevada Rate of Spread Study was conducted on three sites throughout Nevada in sagebrush.

The Great Basin Live Fuel Moisture Project has shown to be effective in alerting fire personnel of current and potential fire behavior conditions, as well as being an indicator of fire season severity, and is used in determining whether or not prescribed fire plans should be implemented.  The project is archived in Nevada Research Projects at the Denver Service Center (NARSC).  Overall, it has brought an awareness of the role that live fuel moisture conditions play in determining intensity and severity of burning conditions relating to fire behavior.

Basic Concepts

The role of fuel moisture in determining fire behavior is basic, so simple that it can almost be overlooked at times.  The more water in the plant, the more heat will be required to evaporate the moisture before ignition will occur.  Conversely, less moisture in the plant will require less heat and more rapid burning conditions.

In live foliage, the moisture is influenced primarily by the physiological activity for that shrub type.  This usually follows a distinctive pattern from year to year.  During the spring, foliar moisture levels can rise well over 200 percent.  As the season progresses into the dry summer period the foliar moisture begins to fall, reaching minimum levels below 90 percent.  When the shrubs become dormant, the minimum moisture levels are finally reached. 

Reno Study

In 1982 the Nevada State Office began sampling sagebrush foliage from a site to determine live fuel moisture throughout the year.  Following three years of monitoring, fire and aviation staff came to the conclusion that this system could be used to warn fire managers in Nevada of the fire season severity.  The drying of live fuels moisture occurs at different rates from year-to-year following greenup. 

By evaluating the slope immediately after peak greenup (during April in the Reno area), a fire manager can estimate just how early and severe the fire season could be several months ahead of time by applying an average slope value.  This, combined with long range assessments and weather forecasts, can be used to determine whether a fire season might start and indicate how intense the fire season might be.

The Great Basin Live Fuel Moisture Project

In 1985, sampling of sagebrush foliage on 18 select sites began in Nevada.  In 1986, eastern California added ten sites (CDF, US Forest Service, BLM).  In 1986, the Oregon State Office began monitoring live fuel moisture values on the eastern side of the state.  Colorado and Idaho BLM added 8 new sites in 1990.  In 1993, 4 additional sites were added in to the Red Rock National Conservation Area Las Vegas, Nevada.  This was done to determine fuel moisture conditions within the recreation area for fire suppression purposes, as well as providing a means to evaluate the possible closure of the Red Rock Vistor Center.

Each site collects sagebrush foliage for an assigned date and time period.  This occurs every two weeks throughout the fire season.  Please see the link called Sampling Schedule.  Samples are taken from a five-acre site, on random shrubs, on random canopy levels, and from around the plants.  Foliage is then placed into special air-tight containers, sealed, and then sent off for processing at the Nevada State Office.  Special guidance was given to assure proper sampling procedures.  Once received the samples are promptly processed using  pre- and post-weighing of the samples.  The results are compiled into the Great Basin Live Fuel Mositure Report , which includes the amount of change from the last sampling date, general fire behavior predictions of rate of spread and flame length. These results and are posted to this web site.  Every report is included as a set of graphs for each site.  After tracking the live fuel moisture values for more than one year, a specialist can use these graphs to estimate fire start potential.

Every report includes a set of graphs for each district.  After tracking the live fuels moistures for more than one year, a specialist can use these graphs to estimate the beginning of the fire season by plotting the average slope of the graph.

Thousand Hour and Pinyon Pine Live Fuel Moisture Reporting

Fire and aviation staff determined that it was also important to validate NFDRS by taking thousand-hour fuel samples in the mid-1980's.  Thousand- hour fuels are also processed and posted on the Great Basin Live Fuel Moisture website and in a report.  Nine sites have been sampled in the past by the Humboldt-Toiyabe National Forest.

Collaboration

The Nevada State Office fuels staff has cooperated with the Fire Research Station (Missoula) and Earth Resource Observation System (EROS) in the development of a Land Characterization Study.  The data was validated and is now being used in the experimental live fuel moisture graph from the Missoula Fire Lab. 

Fire Behavior Analysts (FBANs) and Long-Term Risk Assessment Fire Behavior Analysts (LTANs) use this data during Type I and II incidents.  The data can be used in planning of prescribed burns, preparation of severity requests and for fire planning purposes.