Impact of climatic variability on the fire behaviour of different land ecosystems
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Date
2011Author
Viegas de Barros, Ana Lúcia
Metadata
Abstract
Wildfires are a natural phenomenon that strongly impacts the
environment. Many terrestrial ecosystems depend on fire to maintain
their ecological equilibrium and biodiversity, but new destructive
fire patterns, often associated with land management practices and
rapid climate change, have been degrading soil and water resources,
increasing erosion by wind, precipitation and floods, decreasing
biodiversity and contributing to desertification. Furthermore,
pyrogenic emissions from biomass burning are an important source of
atmospheric pollution and they impact the radiative balance of the
troposphere, strongly contributing to the greenhouse effect. The
objective of this research was to investigate the impact of climate
variability on geographic, ecological, seasonal and inter-annual
distributions of fires and correspondent pyrogenic emissions, across
a variety of ecosystems. With this purpose, 10 years of world,
monthly, 1°x1° gridded data, from the Global Fire Emissions Database,
were compared with land-cover data, from the Goddard Institute of
Space Studies, and with weather data, from the European Centre for
Medium Range Weather Forecasting, the Global Precipitation
Climatology Centre and the Global Hydrology Resource Centre.
Overall, the climate parameters significantly correlated with carbon
emissions were air and soil temperature, air and soil humidity,
rainfall, wind speed and lightning density during the fire season,
and also precipitation and snow cover up to 6 months before the fire
season. Good statistical quantitative models of carbon emissions
(correlations above 70%, and up to 95%, between estimated and
predicted values, with residuals normally distributed) using
humidity, temperature or lagged rainfall as predictors, were found
almost exclusively in tropical grasslands, shrublands and woodlands,
especially in Africa, where fire behaviour was more regular. In
boreal and temperate forests and woodlands, where fire patterns were
irregular and fire returning periods were larger, there were not
enough fires, in 10 years of data, to obtain useful predictive
statistical models. The fire models presented here, together with
the quantitative statistical relationships found between climate and
fire patterns, in different land ecosystems, are apt to be used in
predictive climate models, land management, fire risk assessment and
mitigation of climate change.