FUEL MODELING IN Eucalyptus dunnii PLANTATIONS IN TRÊS BARRAS COUNTY, SC, BRAZIL

Abstract

An inventory was conducted in the Três Barras county, state of Santa Catarina, Brazil (latitude 26^o15’ S; longitude 50^o48’W), in order to develop predicting models for fuel loading in Eucalyptus dunnii plantations.  Sampling was done in stands with 22, 34, 55, 78, 92, 103, 113 and 124 months of age, covering the whole rotation of the plantations. Twenty plots (1.0x1.0m) were randomly located in each stand, totalizing 160 plots. The independent variables measured in the stands were age (in months), DBH (cm), dominant DBH (cm), dominant height (m) of the trees, basal area (m²), and understory vegetation height (m). The dependent variables were live surface fuel, dead foliage, dead woody fuel (separated by size classes), and total fuel load, measured in ton.ha^-1.  Results showed good correlation between age of the plantations and most of the dependent (fuel related) variables. Live surface fuel only presented significant correlation with the understory vegetation height. Models were developed to estimate the following variables: live surface fuel (W_v), dead fuel up to 10 hour (Æ£ 2.5cm) timelag  (W_d), dead foliage (W_f), and total fuel load (W_T). Independent variables were chosen not only by the correlation coefficients, but also for the measuring facility, and based on these principles age (I), basal area (G), and understory vegetation height (H_v) were selected.  Plantations age was the variable that provided best fits for all predicting models, except live surface fuel, that was best predicted through the understory vegetation height and basal area. The selected model to estimate total fuel loading was:   W_T  = 17.256106 – 0.28177*I + 0.003182*I². Total fuel load in the Eucalyptus dunnii plantations in the studied site ranged from approximately 8.0 to 31.0 ton.ha^-1, depending on the plantation’s age.