Investigations of on farm seedling productivity of the rare and declining Caesalpinia bonduc in Benin (West Africa) by aid of simulation modelling – IJAAR

EA.Padonou, AE. Assogbadjo, R. Glèlè Kakaï, AM. Lykke, B. Sinsin, J. Axelsen

University of Abomey, Calavi, Faculty of Agronomic Sciences,Cotonou, Benin

Laboratory of Biomathematics and Forest Estimations, University of Abomey-Calavi, Cotonou, Benin

Aarhus University, Department of Bioscience, Silkeborg, Denmark

Key words: Caesalpinia bonduc, Simulation model, Harvesting intervals sustainable use, Plantations.

Abstract

Caesalpinia bonduc is overexploited and threatened due to its importance in medicine. This study aims at assessing on farm seedling productivity of C. bonduc by aid of simulation modelling in order to design its appropriate plantation techniques, harvesting intervals, and soil conditions. Data were collected from nursery and field experiments by measuring stem height, collar diameter, number of leaves and tap root length during 180 days. The simulation model was based on a metabolic pool type model calibrated first to simulate the observed growth data from the nursery (calibration). Following it was used to simulate the growth of plants from field experiments, first by an optimization of the utilization of leaves or roots only, and second by an optimization of the utilization of both leaves and roots at the same time at different plant densities and nitrogen levels. The models show that in order to optimize the utilization of C. bonduc it should be planted at high densities with high nitrogen levels. Leaves and roots harvesting should take place every 50-60 days, and maximum 15% of the biomass of roots and leaves should be harvested at each harvesting event.