Foliar Resorption of Nutrients in Selected Sympatric Tree Species in Gallery Forest (Black Sea Region)

Abstract

Gallery forests in Central Black Sea Region are dominated by Platanus orientalis L. The studies were performed in four sites (Mert River, Adalar, Kurupelit and Taflan Regions) located in V-shaped river valleys and differing with soil conditions. Nutrient concentrations were measured in green and senescent leaves in selected sympatric tree species. Foliar nutrient resorption efficiency (RE; as the ratio of the resorbed amounts of nutrient losses during the leaf senescence to its prior amount deposited in the leaves) and proficiency (RP; the level to which nutrient content per unit leaf mass, mg g-1, has been reduced in senescent leaves) were examined in several sympatric species. The high nitrogen resorption efficiency (N-RE) (62%) were found in Hedera helix L., while the lowest (40%) - in Salix alba L. The phosphorus resorption efficiency (P-RE) ranged between 35% (Rubus discolor Weithe and Nees) and 50% (S. alba) and that of potassium (K-RE) ranged between 49% (S. alba) and 62% (Robinia pseudoacacia L.). The different trend was observed in the values of proficiency (RP). The high nitrogen resorption proficiency (N-RP) ranged between 10 mg g-1 (Clematis vitalba L.) and 18 mg g-1 (R. discolor). The high phosphorus resorption proficiency (P-RP) was found in R. discolor (0.5 mg g-1) similar to N-RP. The lowest P-RP was found in R. pseudoacacia (0.3 mg g-1) like K-RP (5 mg g-1). The high K-RP (10 mg g-1) was found in H. helix. There is no significant difference between four study sites. Soil N, P and organic matter concentrations were significantly correlated with green-leaf N, P and K concentrations. Significant correlations were also found between K-RP and soil nutrient concentrations and soil moisture. However, no significant correlations were found among green-leaf nutrient concentrations, RE, RP and soil nutrient concentrations and moisture.