Predicting Potential Density and Basal Area Development in the Social Forestry Plantations of Acacia nilotica in Gujarat State of India

ABSTRACT

Growth modelling is an important and effective tool for evaluating the effects of a particular management action on the future development of a forest ecosystem. However, such necessary growth models are not available for many indigenous tree species in India. Acacia nilotica is an important multipurpose tree species found in India and growth models are required for proper management of the species in the region. This paper presents equations for estimating potential stand density and predicting basal area in pure even-aged stands of A. nilotica in Gujarat State of India. Although no thinning was suggested, decrease in the number of trees in the stands was observed because of mortality due to overcrowding and some biotic factors. Relationships between quadratic mean diameter and stems per hectare were developed, which was used to establish the limiting density line. Eight different stand level models, belonging to the path invariant algebraic difference form of a non-linear growth function, were compared for projecting basal area. They can be used to predict future basal area as a function of stand variables like dominant height and stem number per hectare and are crucial for evaluating different silvicultural treatment options. The performance of the models was evaluated using different statistical criteria to recommend the suitable model for projecting the basal area in A. nilotica stands.

KEYWORDS:

• Acacia nilotica
• even-aged plantation
• limiting line
• path invariant algebraic difference form of basal area models
• model evaluation
• India

The author wishes to thank the staff of Forest Management Unit of the Arid Forest Research Institute (AFRI) for their help rendered during the data collection. He would also like to thank the Director, AFRI for providing necessary support during the course of the study.