Data from: Frequent fire slows microbial decomposition of newly deposited fine fuels in a pyrophilic ecosystem

Frequent fires maintain nearly 50% of terrestrial ecosystems, and drive
ecosystem changes that govern future fires. Since fires are dependent on
available plant or fine fuels, ecosystem processes that alter fine fuel
loads like microbial decomposition are particularly important and could
modify future fires. We hypothesized that variation in short-term fire
history would influence fuel dynamics in such ecosystems. We predicted
that frequent fires within a short-time period would slow microbial
decomposition of new fine fuels. We expected that fire effects would
differ based on dominant substrates and that fire history would also alter
soil nutrient availability, indirectly slowing decomposition. We measured
decomposition of newly deposited fine fuels in a Longleaf pine savanna,
comparing plots that burned 0, 1, 2, or 3 times between 2014 and 2016, and
which were located in either close proximity to or away from overstory
pines (Longleaf pine, Pinus palustris). Microbial decomposition
was slower in plots near longleaf pines and, as the numbers of fires
increased, decomposition slowed. We then used structural equation modeling
to assess pathways for these effects (number of fires, 2016 fuel/fire
characteristics, and soil chemistry). Increased fire frequency was
directly associated with decreased microbial decomposition. While
increased fires decreased nutrient availability, changes in nutrients were
not associated with decomposition. Our findings indicate that increasing
numbers of fires over short-time intervals can slow microbial
decomposition of newly deposited fine fuels. This could
favor the fine fuel accumulation and drive positive
feedbacks on future fires.