FIRE INTENSITY AND SEVERITY IN BRAZILIAN CAMPOS GRASSLANDS

Brazilian Campos grasslands are rich in species and the maintenance of its diversity and physiognomy is dependent on disturbance (e.g. fire and grazing). Nevertheless, studies about fire intensity and severity are inexistent. The present paper describes fire parameters, using 14 experimental burn plots in southern Brazil (30 degree 02' to 30 degree 04'S, and 51 degree 06' to 51 degree 09'W, 311masl). Two sites under different fire histories were chosen: frequently burned and excluded since six years. Experimental burning was performed during summer (2006-2007), when most burning takes place in these grasslands. The following parameters were measured: air temperature and moisture, vegetation height, wind speed, fuel (fine, coarse), fuel moisture, fire temperatures (soil level and at 50cm), ash, residuals, flame height, fire duration; burning efficiency and fire intensity were later calculated. Fuel load varied from 0.39 to 1.44kg times m super(-2), and correlated positively with both fire temperature and fire intensity. Fire temperatures ranged 47 to 537.5 degree C, being higher in the excluded site. Fire intensity was low compared to grassland elsewhere (36.5-319.5kW times m super(-1)), differing significantly between sites. Fine fuel was the variable that best explained fire intensity. The results on fire intensity and severity in Campos grasslands can be considered a pilot study, since plots were very small. However, the data provided can help other researchers to get permission for experimentation using larger plots. The results provide support for further studies about the effects of fire on grassland vegetation and for studies involving fire models and fire risk prediction.Original Abstract: Los pastizales o Campos Sulinos del Brasil se caracterizan por gran riqueza de especies, y el mantenimiento de su diversidad y fisonomia depende de perturbaciones como fuego y pastoreo; sin embargo, no hay estudios sobre intensidad y severidad de fuegos. Se describen pardmetros del fuego, usando 14 parcelas de quemas experimentales en el sur de Brasil (30 degree 02'-30 degree 04'S, y 51 degree 06'-51 degree 09'O, 311msnm). Se eligieron dos sitios con diferentes historias de quemas: una frecuentemente quemada y otra con seis anos de exclusion de quemas. Se realizaron quemas experimentales durante el verano (2006-2007), cuando ocurre la mayor parte de los incendios. Se midieron temperatura y humedad del aire, altura de la vegetacion, velocidad del viento, acumulacio