Effect of stand, topographic, and climatic factors on the fuel complex characteristics of Aleppo (Pinus halepensis Mill.) and Calabrian (Pinus brutia Ten.) pine forests of Greece

In this study we examined the effect of stand, topographic, and climatic factors on the fuel complex characteristics of Aleppo (Pinus halepensis Mill.) and Calabrian (Pinus brutia Ten.) pine forests of Greece, based on measurements in fifty six (56) plots dominated by Aleppo pine (28 plots) and Calabrian pine (28 plots) in four different forest sites. The data were analyzed through Random Forest regression, linear regression, and quantile regression. The results showed that for all the examined factors, basal area, stand density index and stand height were the most important factors explaining fuel complex characteristics in the region for both species. Topography and climate factors were not found to be significant factors for canopy fuels. However, elevation and annual precipitation showed a minor effect mainly on the shrub fuel layer of Calabrian pine. The analysis and the conclusions of the study can be important inputs for forest management decisions (thinning, fuel treatments, stand regeneration planning) quantifying the effect that certain fuel management actions can have on the fuel hazard that the stands of these two important Mediterranean pines represent.