Demonstration and application of selective thinning regimes for the production of quality wood material of yemane (Gmelina aborea) for the furniture industry

The project, principally aimed at demonstrating and applying selective thinning practices in order to produce quality wood material of Yemane (Gmelina arborea) for the furniture industry and to show the effects of these thinning practices on surface run-off and erosion, was implemented in Mindanao representing Type 4 climate (no pronounce wet and dry season) and in Isabela representing Type 1 climate (distinct wet and dry season). Thinning both 30% and 50% generated sufficient amount of volume that can be utilized in agricultural farming and in light construction. This volume of wood if not extracted through thinning will just be wasted since the trees will dry and rot due to competition. In both study sites, thinning had only significant effect on diameter growth during some periods. However, cumulative diameter growths for 4 1/2 years of Gmelina stand of unthinned and thinned stands were not significantly different. Some of the possible reasons could be: a) reduction of the number of stems may have drastically change the micro environment that probably has caused negative effects on thinned Gmelina stand, b) timing of thinning may not be appropriate since the stand was already 7 years old when such silvicultural treatments were done, c) genetic, make-up of the provenance used may be poor and, d) site and site quality may not be compatible with this species. Noticeably, the patterns of surface run-off and erosion have been study sites, the quantities of surface run-off (SRD) and soil erosion (SE) were consistently lowest in control than the 30% and 50% thinning. However, no significant differences were found between the thinned and unthinned Gmelina stand. This means that the reduction of the number of trees or crown cover (responsible for rainfall interception) due to thinning did not significantly increase the rainfall reaching the ground or this did not affect the water infiltration of the soil or this did not affect the vegetation on the ground.