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Reference details

Title
(in the language of the original copy)
MEDPINE4: P4-21 - Post-fire recruitment of Pinus pinaster (Ait.) – the importance of fire severity
English translation MEDPINE4: P4-21 - Post-fire recruitment of Pinus pinaster (Ait.) – the importance of fire severity
Reference Identifier 2880
Written by MAIA, P; VASQUES, A; FERNANDES, I; PAUSAS, J; KEIZER, J
Keywords stand dynamic and forest management, Pinus pinaster (Ait.), post-fire recruitment, severity
Concerned Units

Wildland fire, ecosystems functioning and bio-diversity

Phoenix related ? This reference IS related to Phoenix project
JPG Image Poster at the 4th International Conference on Mediterranean Pines, June 6-10 2011, Avignon – France

Issued in 06 / 2011 and originally written in English.
To obtain it, please contact its current manager through email.


Summary (in the language of the original copy) English summary
This study focuses on the investigation of the Pinus pinaster recruitment, after a heterogeneous severity fire, in order to analyse 1) in what extent the regeneration is affected by different severities and 2) which fire severity index, from the ones used here, correlates better with post-fire P.pinaster recruitment, and therefore, is of better use from a post-fire management point of view. The study area is a west facing slope with Pinus pinaster plantation, burned in August 2008, at 30 years of age. It is located in Colmeal, Central Portugal, in the mountain range of Serra da Lousã, in the border between the municipalities of Góis and Arganil. No serotinous cones have been observed for this population, leading to conclude that, in this case, the soil seed bank may play a more important role than the aerial seed bank. The study sites were chosen according to a global, straightforward categorization of the fire severity, in two distinct categories. Visual assessment of the burnt slope allowed to identify areas where the canopies where totally charred or consumed, and no green needles were left (High Severity - HS) contrasting with areas where the canopies where only scorched, and eventually some green needles were still present (Low Severity - LS). This categorisation led to the establishment of 3 pairs of transects, in the transition areas of these main fire severity classes; one transect was placed in a LS area, while the other was placed in the neighbouring HS area. Then, 3 plots composed of 4 2.5 x 2.5 squares where established in each transect, and a fire severity index, based on the minimal diameters of the burned twigs was calculated (Twig Severity Index – TSI). For this severity estimation, the diameter of the 3 thinnest twigs of 5 to 10 randomly selected shrubs was measured, and the average diameter found on each plot was weighted by the maximum found on the slope. This resulted in an index ranging from 0 to 1, directly proportional to the fire severity on the plot. Other severity measures, related to the flame height and degree of canopy consumption, were also taken, but won’t be addressed at this stage. The number of P.pinaster seedlings in the plots was monitored in a regular basis, together with other aspects of the post-fire vegetation regeneration. The data analysis is still ongoing. At the slope scale, it was found that P.pinaster seedlings density is roughly twice as high in the plots located in the LS than on the HS areas. The reasons for that may be 1)less mortality of seeds that were already on the soil when the fire occurred or 2) enhanced conditions for germination due to post-fire litter inputs from the canopy. There are evidences of a strong relation between P.pinaster seedling density and the TSI at the transect scale, but not so strong at the plot level, which implies that spatial variability may play an important role. Further data analysis is needed; however, this preliminary analysis suggests that severity may have an important effect on Pinus pinaster recruitment after fire, and that both fire severity classifications approached can be of interest to evaluate the potential for this species’ post-fire regeneration. This study focuses on the investigation of the Pinus pinaster recruitment, after a heterogeneous severity fire, in order to analyse 1) in what extent the regeneration is affected by different severities and 2) which fire severity index, from the ones used here, correlates better with post-fire P.pinaster recruitment, and therefore, is of better use from a post-fire management point of view. The study area is a west facing slope with Pinus pinaster plantation, burned in August 2008, at 30 years of age. It is located in Colmeal, Central Portugal, in the mountain range of Serra da Lousã, in the border between the municipalities of Góis and Arganil. No serotinous cones have been observed for this population, leading to conclude that, in this case, the soil seed bank may play a more important role than the aerial seed bank. The study sites were chosen according to a global, straightforward categorization of the fire severity, in two distinct categories. Visual assessment of the burnt slope allowed to identify areas where the canopies where totally charred or consumed, and no green needles were left (High Severity - HS) contrasting with areas where the canopies where only scorched, and eventually some green needles were still present (Low Severity - LS). This categorisation led to the establishment of 3 pairs of transects, in the transition areas of these main fire severity classes; one transect was placed in a LS area, while the other was placed in the neighbouring HS area. Then, 3 plots composed of 4 2.5 x 2.5 squares where established in each transect, and a fire severity index, based on the minimal diameters of the burned twigs was calculated (Twig Severity Index – TSI). For this severity estimation, the diameter of the 3 thinnest twigs of 5 to 10 randomly selected shrubs was measured, and the average diameter found on each plot was weighted by the maximum found on the slope. This resulted in an index ranging from 0 to 1, directly proportional to the fire severity on the plot. Other severity measures, related to the flame height and degree of canopy consumption, were also taken, but won’t be addressed at this stage. The number of P.pinaster seedlings in the plots was monitored in a regular basis, together with other aspects of the post-fire vegetation regeneration. The data analysis is still ongoing. At the slope scale, it was found that P.pinaster seedlings density is roughly twice as high in the plots located in the LS than on the HS areas. The reasons for that may be 1)less mortality of seeds that were already on the soil when the fire occurred or 2) enhanced conditions for germination due to post-fire litter inputs from the canopy. There are evidences of a strong relation between P.pinaster seedling density and the TSI at the transect scale, but not so strong at the plot level, which implies that spatial variability may play an important role. Further data analysis is needed; however, this preliminary analysis suggests that severity may have an important effect on Pinus pinaster recruitment after fire, and that both fire severity classifications approached can be of interest to evaluate the potential for this species’ post-fire regeneration.

Author's complete information

MAIA, P; VASQUES, A; FERNANDES, I; PAUSAS, J; KEIZER, J
Institut National de la Recherche Agronomique, Centre de Recherches de PACA(National Institute for Agronomic Research, PACA Research Centre)

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IJWF Reference

MAIA, P; VASQUES, A; FERNANDES, I; PAUSAS, J; KEIZER, J, 2011. MEDPINE4: P4-21 - Post-fire recruitment of Pinus pinaster (Ait.) – the importance of fire severity . Poster at the 4th International Conference on Mediterranean Pines, June 6-10 2011, Avignon – France

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