Seasonal changes of nutrient levels and nutrient resorption inAvicennia marinaleaves in Yingluo Bay, China

Abstract

Avicennia marina is a typical mangrove species of subtropical coastlines of China. However, little is known about the retention of nutrients by this species in oligotrophic, coastal environments. In this study, seasonal changes in nitrogen (N) and phosphorus (P) concentrations, N:P ratio and total phenolic concentration in A. marina leaves during senescence were studied. Avicennia marina leaves had high N and P concentrations but the seasonal pattern of N concentration was different from that of P concentration. The A. marina forest was N-limited as the N:P ratio of mature leaves was less than 14. Nitrogen resorption efficiency was higher than P resorption efficiency, and the concentrations of N and P in senescent leaves indicated that N resorption was mostly complete whereas P resorption was incomplete. Avicennia marina leaves contained low tannin concentrations, particularly condensed tannins, as the leaf extracts did not react with acid butanol. Total phenolic concentrations were not correlated with N concentrations in mature and senescent leaves of A. marina. These findings suggest that the high N resorption efficiency and low nutrient losses play an important role in nutrient conservation strategies for A. marina forests, whereas low tannin concentations have limited effects on nutrient cycling.

Nutrient Resorption and Phenolics Concentration Associated with Leaf Senescence of the Subtropical Mangrove Aegiceras corniculatum: Implications for Nutrient Conservation

“…All the same, NRP and PRP values were lowest in spring when A. corniculatum grew rapidly. This is in agreement with the findings by Wei et al [9], which suggested that lower N and P concentrations of senescent leaves in growing seasons in comparison to other seasons make it difficult to resorb additional nutrients.…”

“…Nutrient resorption during leaf senescence serves to reduce the plant's dependence on current nutrient supply, and has been recognized as one of the most important strategies used by plants to conserve nutrients [8,9,34,35]. It has been estimated that approximately 50% of the nutrients (N and P) are resorbed during leaf senescence [29,36].…”

Leaf Nutrient Resorption and Export Fluxes of Avicennia marina in the Central Red Sea Area

“…And up to 72% for P resorption by Alongi (2002), also P resorption has been reported for a number of Avicennia marina stands Ochieng and Erftemeijer, 2002;Alongi et al, 2005;Lovelock et al, 2007Lovelock et al, , 2010Lovelock et al, , 2011Zhou et al, 2010;Wei et al, 2015). Additionally, iron resorption in mangroves has not been assessed as yet.…”