Thresholds and alternative states in neotropical dry forest in response to fire severity, 2005-2018

Neotropical xerophytic forest ecosystems evolved with fires that
shaped their resilience to disturbance events. We asked if there is
evidence for a fire severity threshold causing an abrupt transition
from a forest to an alternative shrub thicket state in the presence of
typical post-fire management. We studied a heterogeneous wildfire
event to assess medium-term effects (11 years) of varying fire
severity in a xerophytic Caldén forest (Prosopis caldenia) in La Pampa
province, central Argentina. We conducted field vegetation surveys in
patches that were exposed to low (LFS), medium (MFS), and high (HFS)
fire severities, but had similar pre-fire woody canopy cover.
Satellite images were used to quantify fire severity using a delta
Normalized Burning Ratio (dNBR) and to map pre-fire canopy cover. The
structure and composition of woody and herbaceous vegetation was
measured during the 2017-18 growing season (September to March) in
areas affected by different severities of the 2006 wildfire.