A three parametric logistic function was applied to quantify and compare tree height vs time data sets of three important forestry plant species, viz. Leucaena leucocephala, Acacia auriculiformis and Eucalyptus citriodora growing naturally at Okhla Bird Sanctuary, located within the National Capital Region, Delhi and is a part of protected area network of the state of Uttar Pradesh. Cumulative growth rate (CGR), absolute growth revenue (AGR) and relative growth rate (RGR) was calculated for all species and eventually compared. RGR was calculated both as a function of time and predicted height. Upper asymptotic values of cumulative height growth were found to be highest in L. leucocephala, followed by E. citriodora and A. auriculiformis. Time-dependent RGR data suggested that RGR decreased with time following the order L. leucocephala >A. auriculiformis >E. citriodora. However, size dependent RGR demonstrated a different trend. Due to low rate of decline, L. leucocephala had the superior RGR followed by E. citriodora and A. auriculiformis. In other words, A. auriculiformis had the lowest final height and a sharp decline in RGR in comparison to the other two species. The cumulative and relative growth data for all the three species fitted well to the logistic model in terms of model performance. Model parameters were statistically significant.

Key words: Cumulative growth rate, absolute growth rate, relative growth rate, logistic function