Growth Performance of Planted Indigenous Trees 12 years from Establishment

Abstract

This tree domestication research is an ex-situ conservation effort aimed to find out the growth performance of some indigenous timber species planted outside their natural forest habitat in Bohol Island, Central Philippines. Specifically, the study sought to characterize the growing conditions of the sites and the biometrics of the trees in three sites after 12 years of growth. We also wanted to find out the best “performers” when grown outside the natural forest habitat. Only indigenous trees were used and planted in a mixed manner. Most of the planting materials were selected wildlings from the local forests. A few were brought in from the nearby island of Leyte. Standard biometrics of trees were taken of all trees. A total of 1,040 trees belonging to 49 species and 25 plant families in 3 land parcels were inventoried. The three sites totaled 2.5 hectares located within the same village and similar growing conditions. These were typical degraded karst areas: shallow soils with pebbles and rock outcrops dotting the landscape. Scrubby vegetation and few scattered trees were the precursor vegetation. The sites used to be cogonal for a long time before scrubby vegetation set in. Annual rainfall is about 2,000 mm; flat to rolling topography; elevation of 320 meters above sea level. Daytime temperature ranges from 24-28 degrees Celsius most of the year and 28-33 degrees during summer (March-May). The standout performers were Terminalia microcarpa, Shorea contorta, Vatica mangachapui, Shorea palosapis, Parashorea malaanonan, and Dracontomelon dao. The biggest Terminalia microcarpa area measured 48 cm in diameter at breast height (dbh). Shorea contorta had a dbh of 29 cm and had a total height of 29 meters. Shorea assamica did not do well in the sites, and was stricken by dieback of unknown cause. Quisumbing guisok was noted to be very sensitive to moisture stress from seedling to the sapling stage. At 12 years, many forest-based timbers including dipterocarps responded well to domestication or ex-situ conservation even in a degraded karst land in tropical Philippines.