Developing post-fire Eucalyptus globulus stand damage and tree mortality models for enhanced forest planning in Portugal

Abstract

Forest and fire management planning activities are carried out mostly independently of each other. This paper discusses research aiming at the development of methods and tools that can be used for enhanced integration of forest and fire management planning activities. Specifically, fire damage models were developed for Eucalyptus globulus Labill stands in Portugal. Models are based on easily measurable forest characteristics so that forest managers may predict post-fire mortality based on forest structure. For this purpose, biometric data and fire-damage descriptors from 2005/2006 National Forest Inventory plots and other sample plots within 2006, 2007 and 2008 fire areas were used. A three-step modelling strategy based on logistic regression methods was used. In the first step, a model was developed to predict whether mortality occurs after a wildfire in a eucalypt stand. In the second step the degree of damage caused by wildfires in stands where mortality occurs is quantified (i.e. percentage of mortality). In the third step this mortality is distributed among trees. Data from over 85 plots and 1648 trees were used for modeling purposes. The damage models show that relative damage increases with stand basal area. Tree level mortality models indicate that trees with high diameters, in dominant positions and located in regular stands are less prone to die when a wildfire occurs.

Modeling Post-Fire Mortality in Pure and Mixed Forest Stands in Portugal—A Forest Planning-Oriented Model

“…This is in concordance with other studies [17,18,20,33]. In addition, size (dbh) has a greatest effect on mortality rate at the level of the individual tree, with larger trees size exhibiting mortality rates much lower than smaller trees, consistent with a decrease in mortality reported by several studies [18,26,71]. These two variables are related, so for a fixed value of basal area (G) if the stand density increases, it means that average tree diameters are smaller.…”

“…The coefficients of biometric variables regarding stand structure are in concordance with findings from international studies (e.g., [17,75]) and studies focused on Portuguese conditions [18,26,34]. The stand-level model indicates that even-aged stands with higher tree diameters have lower probabilities of mortality after a fire than irregular stands with smaller-sized trees (model PsDead).…”

“…The predicted proportion of dead trees in pure maritime pine stands using the stand-level mortality model PdMort presents a very similar response pattern than the model developed by Garcia-Gonzalo et al [18]. If model PdMort is used for pure eucalyptus stands, it also gives similar results as the model developed by Marques et al [26].…”

Developing wildfire risk probability models for Eucalyptus globulus stands in Portugal

“…Firstly, these plots were further inventoried to get the diameter of stumps from trees that burned and had been harvested. Secondly, this diameter was input to an equation developed by Marques et al (2011b) to estimate the pre-fire tree diameter at breast height. Thirdly, the latter was input to an equation developed for eucalypt by Tomé et al (2007) to estimate the tree height (eqn.…”

“…It was demonstrated that in general wildfire impacts depend on the forest cover types where they occur (Moreira et al 2001, Godinho-Ferreira et al 2005, Nunes et al 2005. The characterization of these impacts on eucalypt plantations was addressed recently by Fernandes et al (2011) andMarques et al (2011b). Nevertheless, no models to assess the impact of changes in controllable biometric variables on fire occurrence in eucalypt plantations were available in Portugal.…”