Climate controls on the variability of fires in the tropics and subtropics

Abstract

[1] In the tropics and subtropics, most fires are set by humans for a wide range of purposes. The total amount of burned area and fire emissions reflects a complex interaction between climate, human activities, and ecosystem processes. Here we used satellite-derived data sets of active fire detections, burned area, precipitation, and the fraction of absorbed photosynthetically active radiation (fAPAR) during [1998][1999][2000][2001][2002][2003][2004][2005][2006] to investigate this interaction. The total number of active fire detections and burned area was highest in areas that had intermediate levels of both net primary production (NPP; 500-1000 g C m À2 year À1 ) and precipitation (1000-2000 mm year À1 ), with limits imposed by the length of the fire season in wetter ecosystems and by fuel availability in drier ecosystems. For wet tropical forest ecosystems we developed a metric called the fire-driven deforestation potential (FDP) that integrated information about the length and intensity of the dry season. FDP partly explained the spatial and interannual pattern of fire-driven deforestation across tropical forest regions. This climate-fire link in combination with higher precipitation rates in the interior of the Amazon suggests that a negative feedback on fire-driven deforestation may exist as the deforestation front moves inward. In Africa, compared to the Amazon, a smaller fraction of the tropical forest area had FDP values sufficiently low to prevent fire use. Tropical forests in mainland Asia were highly vulnerable to fire, whereas forest areas in equatorial Asia had, on average, the lowest FDP values. FDP and active fire detections substantially increased in forests of equatorial Asia, however, during El Niño periods. In contrast to these wet ecosystems we found a positive relationship between precipitation, fAPAR, NPP, and active fire detections in arid ecosystems. This relationship was strongest in northern Australia and arid regions in Africa. Highest levels of fire activity were observed in savanna ecosystems that were limited neither by fuel nor by the length of the fire season. However, relations between annual precipitation or drought extent and active fire detections were often poor here, hinting at the important role of other factors, including land managers, in controlling spatial and temporal variability of fire.

Interannual Changes of Fire Activity in the Protected Areas of the SUN Network and Other Parks and Reserves of the West and Central Africa Region Derived from MODIS Observations

“…Fire monitoring is therefore a necessity if we want to improve the management of most African parks and reserves [7,8]. Last but not least, the projected climate changes will most probably have a strong impact on the distribution of habitats [41] and on the fire regimes of the African continent [42].…”

Quantifying the role of fire in the Earth system – Part 1: Improved global fire modeling in the Community Earth System Model (CESM1)

“…(5) and the following three datasets: atmospheric observations (Qian et al, 2006), CLM4's land use and land cover change data , and the GFED3 burned area (Giglio et al, 2009). The multi-year (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004) averages of these data are regridded to the T62 resolution of the Qian et al (2006) data.…”

Planning hydrological restoration of peatlands in Indonesia to mitigate carbon dioxide emissions

“…However, if the groundwater level falls below a critical threshold of −40 cm, the dry peat surface becomes susceptible to fire (Takahashi et al 2003;Usup et al 2004;Wösten et al 2008). Fires are most severe during El Niño events, as in 1997/98 when about 2.4-6.8 million ha of peatlands burnt in Indonesia releasing huge amounts of the greenhouse gas CO 2 (Page et al 2002;Van der Werf et al 2008). With a groundwater level at about −100 cm the burn depth was estimated to be 51 cm on average releasing up to 9.4 Gt of carbon dioxide in Indonesia (Page et al 2002).…”