3 research outputs found
Anthromes dispaying evidence of weekly cycles in active fire data cover 70% of the global land surface
Across the globe, human activities have been gaining importance relatively to climate and ecology as
the main controls on fire regimes and consequently human activity became an important driver of the
frequency, extent and intensity of vegetation burning worldwide. Our objective in the present study
is to look for weekly cycles in vegetation fire activity at global scale as evidence of human agency,
relying on the original MODIS active fire detections at 1 km spatial resolution (MCD14ML) and using
novel statistical methodologies to detect significant periodicities in time series data. We tested the
hypotheses that global fire activity displays weekly cycles and that the weekday with the fewest fires
is Sunday. We also assessed the effect of land use and land cover on weekly fire cycle significance
by testing those hypotheses separately for the Villages, Settlements, Croplands, Rangelands,
Seminatural, and Wildlands anthromes. Based on a preliminary data analysis of the daily global active
fire counts periodogram, we developed an harmonic regression model for the mean function of daily
fire activity and assumed a linear model for the de-seasonalized time series. For inference purposes,
we used a Bayesian methodology and constructed a simultaneous 95% credible band for the mean
function. The hypothesis of a Sunday weekly minimum was directly investigated by computing the
probabilities that the mean functions of every weekday (Monday to Saturday) are inside the credible
band corresponding to mean Sunday fire activity. Since these probabilities are small, there is statistical
evidence of significantly fewer fires on Sunday than on the other days of the week. Cropland, rangeland,
and seminatural anthromes, which cover 70% of the global land area and account for 94% of the active
fires analysed, display weekly cycles in fire activity. Due to lower land management intensity and less
strict control over fire size and duration, weekly cycles in Rangelands and Seminatural anthromes,
which jointly account for 53.46% of all fires, although statistically significant are weaker than those
detected in Croplandsinfo:eu-repo/semantics/publishedVersio