Suitability of native tree species for reforestation in the tropical dry forest of Costa Rica

Abstract

The conservation area Guanacaste (ACG, Área de Conservación Guanacaste) created in 1989 with the financial help of the Swedish government was a great research project for the preservation of the dry forests (Sub-Programa de Restauración de Masas Arbóreas). The most important aim was the restoration of the degraded areas and the silvicultural research concerning valuable wood species. Within the scope of this project, experimental forest plantations were established for the first time in the area of the Forest Research Station Horizontes (Estación Experimental Forestal Horizontes: EEFH). The Research Station especially works on forest tree breeding of native tree species of the dry forest. Among other things young trees are cultivated and planted in different mixtures. The investigated area belongs to such a terrain. The forest plantation was established in 1991 and belongs to the oldest experimental areas of the EEFH. There were ten tree species in different combinations on a total area of 29 ha planted. Since the establishment of the plantation, there were measurements taken of the height and diameter of the trees once each year in permanent sample tests. The forest plantation shows different micro sites. In this way the growth of the trees can be influenced. Besides, an effect of the different mixtures of tree species on the thriftiness and the growth form can be possible. In this study there were detailed examinations in tree growth and condition of the soil carried out in small sample tests in August and September of 2001. Furthermore the water content and the resistance to penetration of the soil were determined. In particular humid years there is found stagnant moisture in some parts of the area. The soil profiles of these micro sites were compared with those ones of drier sites. With these examinations the reasons for differences in tree growth should be described.