Growth variations of edaphic specialist species in a reciprocal pot experiment in Sri Lanka

Abstract

Edaphic factors may determine the habitat associations shown by some tropical trees. In Sinharaja, a tropical rainforest in Sri Lanka, about 79% of tree species show habitat preferences. The present study attempted to investigate the role of edaphic factors in determining habitat specialization, using a reciprocal pot experiment with four edaphic specialist species (Agrostistachys hookeri, Semecarpus gardneri, Mesua nagassarium and Agrostistachys intramarginalis). Both Agrostistachys species showed increased growth rates and total biomass when grown in their native soils compared to that of non-native soils, while M. nagassarium showed a better growth in non-native soils. Higher biomass allocation to roots was evident in all species when they were grown in sand-rich valley soil irrespective of their specialized soil type. No significant trend was observed in foliar nutrient concentrations when grown in native or non-native soils. The results suggest that edaphic factors play a vital role in the spatial distribution of Agrostistachys species. This is perhaps due to plants showing more acclimatory shifts when grown in their native soils compared to non-native soils. The results also suggest the importance of other factors such as plasticity, water-use efficiency and herbivory in the spatial distribution of plants.