Performance of seed-seedling continuum of two agroforestry tree species under inter-specific competition

Abstract

The inter-specific competition among species in a mixed-species plantation is inevitable and the degree of competition for available resources determines the success of species’ co-existence. Different species compete and interact for resources at altered physiological and developmental stages. However, most research investigated inter-specific competition at the mature stage. We examined seed germination and seedling growth of two con-familial species, i.e., Albizia saman and Albizia lebbeck and explored inter-specific competition at their early life stages grown in a different proportional mixture through a replacement series experiment. We found that the germination speed and percentage, the probability of seedling emergence and seedling height were significantly higher in A. saman than in A. lebbeck. Moreover, we observed that A. saman showed higher germination performance in mixtures compared to A. lebbeck, although the germination properties of the species did not significantly vary among treatments. Similarly, the seedling height growth did not vary significantly among treatments, when the seedlings of the studied species were mixed in different proportions. However, both species showed mutualistic relationships, which was significantly modulated by A. saman. Our study suggests that the knowledge of variation in early growth performance of these species and their inter-specific competition influence the recruitment success and will determine the population dynamics of a mixed-species plantation. Furthermore, studies examining the competitive relationship between different species would be invaluable for choosing suitable species and applying proper management approaches for the success of any mixed- species plantation at any afforestation and reforestation activities.