This study consists of the development of tree growth models to deduce stands productivity and determine the highest productive species in the conditions of the concerned plantation. Seven Eucalyptus, introduced in the arboretum of Souiniet (north-west of Tunisia, wet Mediterranean bioclimate) in a Cork Oak natural forest, were studied. Stem analysis and non-linear growth modeling regression equations were used to predict wood productivities. Gompertz and Chapman–Richards growth function appeared as being great numerical models to estimate the Eucalyptus tree diameter and height evolutions, respectively. Moreover, an adapted Chapman–Richards model allowed predicting the volume of trees in an efficient manner. The values of mean annual volume productivity of the Eucalyptus spp.studied, allow us to classify them in order of increasing annual productivity, as follows: E. sideroxylon, E. cinerea, E. maidenii, E. macrorhyncha, E. tereticornis, E. viminalis and E. bicostata. The first three Eucalyptus spp. appeared as the best-adapted and most suitable Eucalyptus trees for new plantations in this area. These species had the highest mean annual increments, ranged from 5 to 10 m3.ha−1.year−1 with 15 to 20 years of rotation. E. bicostata is the most promising, with annual average production exceeding 10 m3.ha−1.year−1 after 25 years, and reaching 20 m3.ha−1.year−1 at 40 years old. These modeling approaches provide additional knowledge on the productivity of the different Eucalyptus species, thus enabling forestry operators to simulate the development of forest stands in order to optimize timber production and harvesting.

The effects of fire on forest and Mediterranean scrubs in four regions of Chile were studied. The main objective was to determine different levels of damage in watersheds with forest and native sclerophyllous scrubs belonging to the most valuable plant formations in Central Chile. The methodology consisted of the characterization of sampling areas that were qualitatively and quantitatively compared with the characterization of forests and shrublands without recent affectations of fires. Four regions of Chile were evaluated, where fires are concentrated in areas with sclerophyllous native vegetation. In each region, two sampling areas were selected to study the effects of fire. Three classifications were made based on structure, species composition, and response to fire. These were: deciduous scrub consisting of A. caven (tree), R. moschata (bush), and A. barbata (herbs); sclerophyllous evergreen scrub consisting of L. caustic-C. alba-and a mixed scrub of P. boldus (tree)-R. trinervia (scrub) and A. barbata. A dendrogram was produced on the relative abundances and the Bray & Curtis Similarity Index of the species. In addition, the results indicated an initial stage of damage to the soil structure, erosion processes, and water transport due to hydrophobicity at different levels of fire intensity, but recovery was observed a few weeks after the fire. Recovery was more apparent in the soil structure and cover of the scrub vegetation and later the tree species. These results provide useful background for the preparation of restoration, reforestation programs, and actions for the conservation of plant species vulnerable to the impact of wildfires. | "Fondo de Investigacion del Bosque Nativo" CONAF Project 008/2016 ANID-PFCHA/Doctorado Nacional 2020-21201582