A case study of nutrient retranslocation in four deciduous tree species of West Bengal tropical forest, India

The internal retranslocation of nutrients of senescence leaves is a significant aspect of nutrient dynamics in a forest ecosystems. The present investigation was carried out by considering four types of deciduous tree species (Shorea robusta, Tectona grandis, Schleichera oleosa, and Albizia lebbeck) to assess nutrient resorption efficiency (NuRE) and resorption proficiency (NuRP) of nitrogen (N), phosphorous (P), and potassium (K), as well as seasonal changes of nutrient concentration in green and senescence leaves. Green and senescent leaves were sampled and analysed for NPK concentration by standard methods. Experimental results revealed that the higher nutrition contents were recorded in green leaves than senescence leaves. The highest N and P resorption efficiency (RE) were recorded for S. robusta and lowest for T. grandis (46.74%) and A. lebbeck (37.93%) respectively, whereas T. grandis exhibited the highest resorption efficiency of K (47.67%) and lowest for A. lebbeck (40.29%). Furthermore, the highest percentage of nutrients from mature leaves and soil were transported to the tree body during senescence were 47.0% (S. oleosa), and 21.29% (T. grandis), respectively. Moreover, nutrients were retranslocated from senescent leaves in the order as N > P > K. On the other hand, the nutrient resorption proficiency (NuRP) was highest with respect to N (53.26%) and P (62.07%) for T. grandis and K (59.71%) for A. lebbeck. Similarly, the lowest with respect to N (44.27%) and P (50.91%) for S. robusta, and K (52.33%) for T. grandis. Therefore, it can be concluded that changes in nutrient concentrations in green and senescence leaves could be the possible reason for different retranslocation efficiency. [GRAPHICS]