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Abstract Detail



Ecology

Gao, Xiulin [1], Schwilk, Dylan W [2].

Are there grass flammability traits? Biomass drives grass fire behavior, but canopy species-specific architecture can control surface heating.

Plants fuel wildfire and understanding how plant traits influence fire behavior is necessary for linking species ecology to prediction of fire hazard and fire effects. A growing body of work on fuel and fire behavior points to the potential complexity behind the simple term "flammability", but recently, several authors have argued that it is helpful to narrow in on the important axes of variation in flammability. Studies of leaf litter driven fire suggest that there are two important flammability axes represented by total heat release and maximum rate of heat release (de Magalhães and Schwilk 2012, Cornwell et al. 2015) and Schwilk (2015) has proposed this may be a general result across fuel types. Grasslands are among the most fire prone ecosystems on the planet and fine grass fuels are universally recognized as extremely flammable. Variation in flammability driven by species traits in grasses has generally been assumed to be minor and it is thought that fuel effects on fire behavior in grasslands is driven largely by biomass. We aimed to test the generality of the two-axis flammability model proposed by Schwilk (2015) and to explore the probability that grass traits other than biomass that may control fire behavior differences across grass species. We sampled 8 grass species (8~15 pairs of individuals per species) in shortgrass steppe and mixed grasslands in Texas and New Mexico. We measured canopy traits and conducted burning trials of grass individuals. Principal component analysis (PCA) supported the hypothesis that variation in flammability across species and individuals was largely two-dimensional (first two PCA axes explained 82% of total variance) and these axes largely corresponded to total heat release and maximum rate of heat release. As expected, plant biomass was the first order control of flammability measures, especially on total heat release as that is essentially equivalent to consumed biomass. However, grass architecture expressed as the ratio of biomass above 10cm to that below 10cm had an additional effect on duration of heating which is an important fire behavior metric predicting soil heating and meristem survival. On the other hand, biomass-independent architecture had no effect on the measures associated with rate of heat release (peak temperature, biomass loss rate). These results demonstrate the potential for species-specific variation in architecture to influence local fire effects in grasses, despite broad scale fire behavior being largely driven by fuel load alone


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1 - Texas Tech University, Biological Science, 2500 broadway, lubbock, TEXAS, 79409, United States
2 - Texas Tech University, Biological Sciences, Lubbock, TX, 79409-3131, USA

Keywords:
grass flammability
canopy architecture.

Presentation Type: Oral Paper
Number: 15006
Abstract ID:495
Candidate for Awards:None


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