Modelling height-diameter relationship of fifteen tree species planted on reclaimed agricultural lands with random species effects

Abstract

Taiwan has a long history of reforesting degraded forest lands and reclaimed agricultural lands to improve forest ecosystem services. While the effort has been ongoing since 1950’s, very few studies attempted to understand how tree species planted on these lands are growing. To fill the knowledge gap, we established plots across elevation from 250 to 2500 m above sea level on reforested fruit orchards, betel nut farms, and bamboo plantations. Diameter and height of 15 plantation tree species were measured. Mixed effects modelling framework was applied to model tree height and diameter relationship of the 15 species with the Wykoff model. Random effects were added to species so that species with few observations could share information from species with abundant information. Preliminary results show that stand productivity and tree-level competition have potential effects on height-diameter relationship. Studying height-diameter relationship could assist decision making for better management of ecosystem services of reclaimed agricultural lands.