Differences in Burning Behavior of Live and Dead Leaves, Part 1: Measurements

Abstract

Burning behaviors of individual live and dead leaves were measured in a well-instrumented, well-controlled flat-flame burner. Manzanita (Arctostaphylos glandulosa) branches were harvested from the Chaparral near Riverside, California. Leaves were conditioned to several moisture contents. Two “live” (i.e., not fully dried) groups remained above the fiber saturation point at 34% moisture content (MC; dry basis) and 63% MC. Two “dead” groups were dried to about 4% MC, and one was rehydrated back up to 26% MC. Distinct plateaus in surface temperatures at 175°C were observed while burning live leaves, but dead leaves showed weaker plateaus, if any. Evidence of high internal leaf pressures during burning of live leaves was seen in flame patterns. Moisture was retained in live and dead leaves with local surface temperatures in the 160°C to 220°C range. This article describes the measured results, while a second article describes mass release modeling for the same data set.

Keywords:

• Leaf combustion
• Manzanita
• Moisture content
• Pyrolysis
• Wildfire