Land Cover Type and Fire in Portugal: Do Fires Burn Land Cover Selectively?

The purpose of this study is to investigate if, or under what conditions, fires select given land cover types for burning. If fires burn unselectively then the land cover composition (the proportional area of various land cover types) of individual fires should approximate the land cover composition available in their neighborhood. In this study we test this hypothesis by performing statistical analyses of a data set consisting of paired vectors with the proportions of land cover types present in burned areas and in their respective surroundings. The statistical methods employed (a permutation technique and the Cmax statistic) are commonly used in resource selection studies where data is subject to a unit-sum constraint. The results of the analysis of 506 fires that burned in Portugal in 1991 indicate that fires are selective, with small fires exhibiting stronger land cover preferences than large fires. According to the results of a multiple comparison analysis performed for small fires, there is a marked preference for shrubland followed by other forest cover types, while agriculture is clearly avoided. A similar analysis is performed to test if fire selectivity is related to the ecological region where it occurs. The results obtained in this study contribute to the discussion on the relative importance of fuels as a drivers of fire spread.

[1]  Nairanjana Dasgupta,et al.  A single-step method for identifying individual resources , 2002 .

[2]  B. Manly,et al.  Resource selection by animals: statistical design and analysis for field studies. , 1994 .

[3]  R. Rothermel,et al.  Predicting changes in chaparral flammability , 1973 .

[4]  J. R. Alldredge,et al.  Comparison of some statistical techniques for analysis of resource selection , 1986 .

[5]  H. Anderson.  Aids to Determining Fuel Models for Estimating Fire Behavior , 1982 .

[6]  Paul W. Mielke,et al.  Permutation Techniques Based on Euclidean Analysis Spaces: A New and Powerful Statistical Method for Ecological Research , 1991 .

[7]  Francisco Moreira,et al.  Temporal (1958–1995) pattern of change in a cultural landscape of northwestern Portugal: implications for fire occurrence , 2001, Landscape Ecology.

[8]  Lyman L. McDonald,et al.  Survey and Comparison of Methods for Study of Resource Selection , 1998 .

[9]  Max A. Moritz,et al.  SPATIOTEMPORAL ANALYSIS OF CONTROLS ON SHRUBLAND FIRE REGIMES: AGE DEPENDENCY AND FIRE HAZARD , 2003 .

[10]  Xavier Pons,et al.  Spatial patterns of forest fires in Catalonia (NE of Spain) along the period 1975–1995: Analysis of vegetation recovery after fire , 2001 .

[11]  F. Rego.  lAND USE CHANGES AND WILDFIRES , 1992 .

[12]  Keeley,et al.  Reexamining fire suppression impacts on brushland fire regimes , 1999, Science.

[13]  José M. C. Pereira,et al.  Synoptic patterns associated with large summer forest fires in Portugal , 2005 .

[14]  Richard A. Minnich,et al.  Wildland Fire Patch Dynamics in the Chaparral of Southern California and Northern Baja California , 1997 .

[15]  Jon E. Keeley,et al.  Testing a basic assumption of shrubland fire management: how important is fuel age? , 2004 .

[16]  M. Vasconcelos,et al.  Spatial Prediction of Fire Ignition Probabilities: Comparing Logistic Regression and Neural Networks , 2001 .

[17]  P. Mielke.  Non-metric statistical analyses: Some metric alternatives☆ , 1986 .

[18]  Jon E. Keeley,et al.  Impact of Past, Present, and Future Fire Regimes on North American Mediterranean Shrublands , 2003 .

[19]  R. Minnich.  Fire Mosaics in Southern California and Northern Baja California , 1983, Science.

[20]  S. Cumming.  FOREST TYPE AND WILDFIRE IN THE ALBERTA BOREAL MIXEDWOOD: WHAT DO FIRES BURN? , 2001 .

[21]  J. Agee.  The severe weather wildfire: too hot to handle? , 1997 .

[22]  P. Mielke,et al.  Permutation Methods: A Distance Function Approach , 2007 .

[23]  William L. Baker,et al.  Evaluation of resource selection methods with different definitions of availability , 1998 .

[24]  Nairanjana Dasgupta,et al.  A Multivariate χ 2 Analysis of Resource Selection Data , 1998 .

[25]  Jean Serra,et al.  Image Analysis and Mathematical Morphology , 1983 .