ABSTRACTBackground: Allometric scaling relationships are important in ecology and forestry. The metabolic scaling theory (MST) predicts a universal invariant scaling relationship for tree growth, relating height and diameter to each other.Aims: Data on five tree species (Pinus taeda L., Pinus virginiana Mill., Liquidambar styraciflua L., Liriodendron tulipifera L., and Pinus palustris Mill.) were used to test the predictions from MST on the scaling of heightâdiameter and also diameter growth.Methods: Data on tree height and diameter for five tree species from both natural forests and plantations were collected to study two types of scaling relationships: tree heightâdiameter and stem diameter growth. A reduced major axis of regression analysis model type II was used to determine scaling exponents from each species under different environmental conditions.Results: No universal invariant scaling exponent was found in heightâdiameter and diameter growth for the five species. The scaling varied across natural forests, plantations and scales (e.g., time and number of measured trees). However, in some situations the scaling exponents failed to show significant difference with the predicted values (e.g., 2/3 or 1).Conclusions: Diverse scaling exponents were observed for the five tree species with the scaling relationships varying with environmental settings.