Effects of Effects of light, nutrient and grass competition on growth of seedlings of four tropical tree species

Abstract

The seedling stage is a sensitive and important stage in plant life. Hence, a thorough understanding of the ecology of individual species and environmental characteristics affecting seedling growth is necessary. Resources such as water, nutrient and light are the most important limiting factors that influence seedling survival and establishment. However, the effect of these environmental factors is modified by grass competition in tropical dry forests. In this study, we examined the effects of light and nutrient with and without grass on the growth of seedlings of four common dry tropical plant species, viz. Acacia catechu, Acacia nilotica ssp. indica, Ziziphus mauritiana and Terminalia arjuna. The growth parameters including height, girth, total dry weight, leaf area and number of leaves, relative growth rate in terms of height, diameter and dry weight were recorded for each species under different treatment combinations. All the species behaved differently under studied treatment combinations. Seedlings were more responsive to the nutrient addition in presence of light. Presence of grass had overall negative effect on growth of tree seedlings. Survival was found highest for A. nilotica ssp. indica and lowest for Z. mauritiana while reverse trend was observed for overall growth. We infer from the results that supplementation of nutrients have strong positive effect over the seedling survival and growth even under reduced light and presence of grass competition. Moreover, the findings also revealed that the regular weeding and nutrient supplementation under the existing forest vegetation may help in regeneration of the dry tropical vegetation by reducing seedling mortality even under dense canopy conditions.