LAUSR

This study investigated the seasonal variation in leaf traits of the dominant tree species Shorea robusta Gaertn. of the Madhupur deciduous forest, Bangladesh in order to understand its adaptation with soil environmental conditions. Fully expanded mature leaves of S. robusta and the soil samples were collected from the forest during summer, rainy, autumn and winter seasons. Significant seasonal effects appeared on a number of morpho-physiological traits such as specific leaf area, leaf mass per area, relative water content, dry matter content, chlorophyll content along with stomatal length, breadth, open–close behavior, density and pore index. The values for leaf mass per unit area and chlorophyll content were higher in autumn and winter than other seasons of the year. The highest values of stomatal density and percentage of open stomata were found in summer indicating their probable correlation with the growth season of the plant. Seasonal fluctuation of soil moisture content showed correlation with leaf water and leaf dry matter contents but not with open–close behavior of stomata. Stomatal movement seemed to be related more with leaf K content and the growing season of the plant as indicated by the maximum number of open stomata observed during summer. The highest value of stomatal pore index in summer indicated its role in gaseous exchange during the growing season of the plant. A decline in leaf N and P concentrations in winter compared to other seasons of the year indicated a tendency of nutrient resorption by plants before senescence of leaf occurred. Overall, the present study demonstrated that the interactions between soil properties and leaf traits influenced the adaptation strategies of S. robusta in the Madhupur forest. Findings of this study are relevant for future research to enhance our understanding about the consequences of the seasonal variation in plant traits for ecological processes including species interactions and ecosystem functioning.