Live Fuel Moisture Levels

Live fuel moisture (LFM) is important for assessing fire danger. LFM is defined as the percentage of water content to dry matter content in live vegetation.  Sixty percent is considered critical.

The direct measurement of LFM is done by collecting fresh field samples of Chamise, drying them until all moisture is evaporated, and calculating the water content difference between fresh and dry samples. Field-sampled LFM are gathered at five locations throughout Santa Barbara County. They include Tepesquet, Harris Grade, Cachuma, Refugio and W. Gaviota.

How can fuel have more than 100% moisture?. Moisture content of wildland fuels is expressed in relation to dry weight, not just the proportion of water in the fuel. It is the dry material that provides the heat to evaporate water so that the fuel will burn. The definition of moisture content used here is the ratio of the weight of the water contained to the dry weight of the material, expressed as a percentage. BLM handbook

Chamise is one of the most common shrub species found in southern California chaparral communities. Chamise is evergreen, but it is sensitive to seasonal drought. During southern California’s long dry season, Chamise leaf moisture content drops as soil water availability declines. In extreme conditions, rapid dry down can happen in days, for example during Santa Ana winds affecting southern California.

Below are the latest LFM levels for Santa Barbara County:

January 2017

For general questions about hazard reduction or vegetation management, contact  (805) 681-5500.