Development of Site Index Equation and Curves for Site Quality Assessment of Pinus caribea Monoculture Plantations in Southwestern Nigeria

Abstract Forest timber production potential of any site is oftentimes measured quantitatively by site index, which is defined as dominant height of a particular stand at a specified age. A site index was developed for estimating site quality of monoculture Pinus caribaea plantations in southwestern Nigeria using a base age of 25 years. Dominant height data were collected from 60 Temporary Sample Plots (TSPs) of 20x20 m in plantations of 15 to 37 years. Linear and non-linear models as been widely applied in quantitative forest measurements were fitted to dominant height- age data and the best site index equation is : SI=Exp (InHd-23.495 (A -0.04) . The site index curves constructed for the three sites (Omo Forest Reserve - OFR (J4), Oluwa Forest Reserve - OLFR and Shasha Forest Reserve - SFR) across the southwestern Nigeria using the chosen equation revealed that a 15 year old Pinus caribaea in the study area attained average dominant heights of 25, 22 and 21 m in OFR (J4), OLFR and SFR respectively. The site index equation and curves proffer veritable insight into better silvicultural options and management practices for the future plantations suitable sites. Key Words: site quality, dominant height, index age, Pinus caribaea, timber production potential