Feedbacks between fuel reduction and landscape homogenisation determine fire regimes in three Mediterranean areas

Loepfe L., Martinez-Vilalta J., Oliveres J., Piñol J., Lloret F. (2010) Feedbacks between fuel reduction and landscape homogenisation determine fire regimes in three Mediterranean areas. Forest Ecology and Management. 259: 2366-2374.
Enllaç
Doi: 10.1016/j.foreco.2010.03.009

Resum:

In densely populated areas like the Mediterranean, wildfire extent is mostly limited by fire suppression and fuel fragmentation. Fire is known to spread more easily through high fuel loads and homogenous terrain and it is supposed to reduce fuel amount and continuity, creating a negative feedback. Here we combine information from administration fire records, satellite imagery fire scars and land use/cover maps to asses the effects of fire on landscape structure and vice versa for three areas in Catalonia (NE Spain). We worked with three spatial focuses: the actual fire scar, 1 km2 squares and 10 km2 squares. In these regions agriculture land abandonment has lead to increased fuel continuity, paralleled by an increment of fire size. We confirm that fire spread is facilitated by land use/cover types with high fuel load and by homogeneous terrain and that fire reduces fuel load by transforming forests into shrublands. But we also found that fire increased landscape homogeneity, creating a positive feedback on fire propagation. We argue that this is possible in landscapes with finer grain than fire alone would create. The lack of discontinuities in the fuel bed diminishes the extinction capacity of fire brigades and increases the risk of large fires. We recommend that fire management should focus more on conservation of the traditional rural mosaic in order to prevent further increases in fuel continuity and fire risk. © 2010 Elsevier B.V. All rights reserved.

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Diseño y aplicación de una propuesta de aprendizaje cooperativo de los contendios del area de Ecología mediante el estudio de casos (inclou versió en anglés) . En “Hacia el espacio europeo de educación superior (EEES). Experiencias docentes innovadoras d

Rodrigo A, Martínez-Vilalta J, Piñol J, Lloret F, Ribas A, Retana J, Losarcos J (2009) Diseño y aplicación de una propuesta de aprendizaje cooperativo de los contendios del area de Ecología mediante el estudio de casos (inclou versió en anglés) . En “Hacia el espacio europeo de educación superior (EEES). Experiencias docentes innovadoras d e la UAB en ciencias sociales y en ciencias humanas”. Maite Martínez y Elena Añaños (eds.). Unitat d’Innovació Docent en Educació Superior. Universitat Autònoma de Barcelona, Servei de Publicacions.

Wildfires. In: J. Woodward (ed.). The Physical Geography of the Mediterranean.

Lloret F, Piñol J, Castellenou M (2009) Wildfires. In: J. Woodward (ed.). The Physical Geography of the Mediterranean. Oxford University Press 541- 558.

Disseny i aplicació d’una proposta d’aprenentatge cooperatiu dels continguts de l’àrea d’Ecologia mitjançant l’estudi de casos. En “Cap a l’espai europeu d’educació superior. Experiències docents innovadores de la UAB en ciències experimentals i tecnol

Rodrigo A, Martínez-Vilalta J, Piñol J, Lloret F, Ribas A, Retana J, Losarcos J (2008) Disseny i aplicació d’una proposta d’aprenentatge cooperatiu dels continguts de l’àrea d’Ecologia mitjançant l’estudi de casos. En “Cap a l’espai europeu d’educació superior. Experiències docents innovadores de la UAB en ciències experimentals i tecnol ogies i en ciències de la salut”. Servei de Publicacions UAB. Bellaterra

Does fire occurrence modify the probability of being burned again? A null hypothesis test from Mediterranean ecosystems in NE Spain

Salvador R., Lloret F., Pons X., Piñol J. (2005) Does fire occurrence modify the probability of being burned again? A null hypothesis test from Mediterranean ecosystems in NE Spain. Ecological Modelling. 188: 461-469.
Enllaç
Doi: 10.1016/j.ecolmodel.2004.12.017

Resum:

Two main causes have been proposed as drivers of fire regime in Mediterranean-type ecosystems: fuel build-up and weather conditions. If fuel build-up is the main cause, then areas recently burned will not burn again until some years later. Contrarily, if weather is the main cause, then all areas will burn irrespective of their age. We have devised a statistical test aimed to distinguish between these two hypotheses. To use the test is necessary to know the spatial distribution of fires during a period of time as long as possible. Then, a percolation algorithm procedure is applied to mimic the location, extent, and perimeter/area ratio of the real fires, independently of previous fire occurrence. This model is run many times and each run is considered a realization under the null hypothesis that a pixel burns irrespectively of whether it was burnt in the previous years. The actual number of pixels burned twice is then compared to the histogram of the probability density function of pixels burned twice, which is obtained from the simulations. Actual values falling in the right tail of the distribution point to a clumped pattern (fires tend to be more abundant in some locations), while falling in the left tail will indicate a segregated pattern (burning reduces the probability of further fires in the same site). The method was applied to three different areas of Catalonia (NE Spain) by comparing the actual fires from 1975 to 1998 to the pattern obtained from random fire simulations. An aggregated pattern was obtained in two of the studied areas when the origin of the simulated fires was located randomly, indicating that fires were not uniformly distributed in the territory. When the simulations were started at the centroids of the real fires, the null hypothesis of independence from previous fires was not rejected, and the fuel-driven assumption was not supported. In the third area, results were inconclusive because two large fires, occurred in 1994, totally changed the results obtained until then. © 2005 Elsevier B.V. All rights reserved.

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Effectes de la sequera sobre l'alzinar mediterrani a Prades.

Martínez-Vilalta J, Mangirón M, Ogaya R, Lloret F, Mastrantonio M, Piñol J, Sardans J, Terradas J, Peñuelas J (1999) Effectes de la sequera sobre l'alzinar mediterrani a Prades. Treb. Cent. Hist. Nat. Conca de Barberà 2:49-60

Efecte "memòria" de la sequera en l'ús de l'aigua i del nitrogen per part de Quercus ilex i Phillyrea latifolia en boscos mediterranis.

Peñuelas J, Filella I, Lloret F, Piñol J, Siscart D (2000) Efecte "memòria" de la sequera en l'ús de l'aigua i del nitrogen per part de Quercus ilex i Phillyrea latifolia en boscos mediterranis. In IV Trobada d'Estudiosos de Sant Llorenç del Munt ide l'Obac, Diputació de Barcelona, Barcelona, pp. 145-148.

Effects of a severe drought on water and nitrogen use by Quercus ilex and Phillyrea latifolia.

Peñuelas J, Filella I, Piñol J, Siscart D, Lloret F (2000) Effects of a severe drought on water and nitrogen use by Quercus ilex and Phillyrea latifolia. Biologia Plantarum 43:47-53.

Climate warming, wildfire hazard and wildfire occurrence in coastal Eastern Spain.

Piñol J, Terradas J, Lloret F (1998) Climate warming, wildfire hazard and wildfire occurrence in coastal Eastern Spain. Climatic Change 38:345-357.

Risk factors in wildfires along the Mediterranean coast of the Iberian Peninsula.

Terradas J, Piñol J, Lloret F (1998) Risk factors in wildfires along the Mediterranean coast of the Iberian Peninsula. In Trabaud L (ed) Fire management and landscape ecology. International Association of Wildland Fire, Washington, pp. 297-304.

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