RESPONSE OF THREE FAST-GROWING TIMBER SPECIES TO DIFFERENT BIOCLIMATES IN ECUADOR

Background: The timber sector in Ecuador holds promising potential for growth and development. The intensive utilization of native taxa has depleted their genetic species pool, making them increasingly scarce in meeting the rising demand for wood. Consequently, there has been a growing exploration of new fast-growing forest species to serve as alternatives for lumber and biomass production. Objective: To assess the suitability of Andean bioclimatic conditions for the introduction of three tree species: Paulownia elongata, P. fortunei, and the hybrid P. elongata x P. fortunei. This work primarily focused in investigating whether plant density impacts the initial growth of individual tree growth and whether there is a co-dependence between site conditions and plant density in each of the three species. Methodology: The National Autonomous Institute of Farming Research (INIAP) imported 3000 seedlings, each about 10cm tall, of Paulownia elongata, Paulownia fortunei, and the hybrid Paulownia elongata x Paulownia fortunei from the World Paulownia Institute of Georgia - USA. Four experimental sites were selected in two regions of Ecuador: humid tropics (Quevedo and Santo Domingo de los Tsachilas), dry sub-peak (el Almendral) and Andes (Riobamba), each site is located at different altitudes. At each site, the experiment was set up in a spatial split-plot arrangement with randomized complete blocks. Three blocks were established, two planting frames (3x3 m and 4x4 m) and the three selected Paulownia species. The three blocks were laid off randomly in each experiment. The two planting frames were randomly placed within each block, and the three species were randomly planted within each planting frame. The experimental subjects (plant species) consisted of nine individuals. Results: Plants with higher height and diameter are located in areas with lower elevation, with hybrid Paulownia displaying better performance in high densities. All species showed a survival rate above 85% one-year post-establishment. However, the lowest survival is found in areas above 2000 m. Implications: High elevations restrict the individual growth of Paulownia in Andean conditions, but low altitudes enhance it. Conclusion: The three specimens performed reasonably well during one-year post-establishment. However, it is necessary to continue observing their growth until they reach their asymptotic point, determining their volumetric yield.