Early response of selected tree species to liberation thinning in a young secondary forest in Northeastern Costa Rica

Short-term growth responses in individuals of four commercial tree species (Laetia procera, Simarouba amara, Tapirira guianensis, and Vochysia ferrugi nea) were evaluated one and two years after 'liberation thinning' in a youn g (4.5-year-old), dense secondary forest stand located in an agricultural s ettlement in wet, Northeastern Costa Rica. Liberation thinning involved man ual elimination (either by cutting or stem girdling) of the adjacent 'ring' of competitors in order to release future crop trees (median diameter: 8 c m DBH), selected on the basis of stem and crown form. The application of li beration thinning significantly increased diameter growth of future crop tr ees with respect to unmanipulated counterparts. Young stands in the region may be attractive systems for simple silvicultural manipulations due to rap id growth responsiveness, facilitated by manageable tree size. Detailed obs ervations on stand development and patterns of crown stratification in coex isting tree species in other dense secondary stands in the area seems warra nted in order to refine silvicultural options aimed at increasing tree diam eter growth. (C) 1999 Elsevier Science B.V. All rights reserved.