@article{ref1,
title="Flammability thresholds or flammability gradients? Determinants of fire across savanna-forest transitions",
journal="New phytologist, The",
year="2020",
author="Hoffmann, William A. and Rossatto, Davi R. and Durigan, Giselda and Abreu, Rodolfo C. R. and Power, Collin R. and Newberry, Brooklynn M.",
volume="228",
number="3",
pages="910-921",
abstract="Vegetation-fire feedbacks are important for determining the distribution of forest and savanna. To understand how vegetation structure controls these feedbacks, we  quantified flammability across gradients of tree density from grassland to forest in  the Brazilian Cerrado. We experimentally burned 102 plots, for which we measured  vegetation structure, fuels, microclimate, ignition success and fire behavior. Tree  density had strong negative effects on ignition success, rate of spread, fire-line  intensity and flame height. Declining grass biomass was the principal cause of this  decline in flammability as tree density increased, but increasing fuel moisture  contributed. Although the response of flammability to tree cover often is portrayed  as an abrupt, largely invariant threshold, we found the response to be gradual, with  considerable variability driven largely by temporal changes in atmospheric humidity. Even when accounting for humidity, flammability at intermediate tree densities  cannot be predicted reliably. Fire spread in savanna-forest mosaics is not as  deterministic as often assumed, but may appear so where vegetation boundaries are  already sharp. Where transitions are diffuse, fire spread is difficult to predict,  but should become increasingly predictable over multiple fire cycles, as boundaries  are progressively sharpened until flammability appears to respond in a  threshold-like manner.<p /> <p>Language: en</p>",
language="en",
issn="0028-646X",
doi="10.1111/nph.16742",
url="http://dx.doi.org/10.1111/nph.16742"
}