Does leaf resorption efficiency always predict plant nutrient status? A
case study from a common mangrove species in China
Abstract
Aims The impact of nutrient increase on nutrient resorption from
senescent leaves is an important topic, which is not completely
understood. Mangrove species are characterized by nutrient conservation
mechanisms as a consequence of adaptation to nutrient-poor environments.
The understanding of the response of the traits related to nutrient
conservation strategies to nutrient availability is limited. This study
aims to address whether nutrient resorption of mangrove species is
responsive to long-term nutrient enrichment. Methods A field-based study
was carried out in a Kandelia obovata dominated mangrove stand where a
nutrient gradient was generated by the long-term discharge of
aquaculture wastewater. Seasonal variations of nutrient resorption and
nutrient availability were assessed. Important findings The data from
summer and winter showed the same results: 1) resorption proficiency or
the nutrient concentrations (N and P) in senescent leaves did not varied
with nutrient increases except the plot that the N availability was
extremely high; 2) the resorption efficiency of both N and P was
positively correlated with nutrient availability, and N resorption
efficiency was also positively correlated to leaf N: P ratio; 3) N
resorption was complete while the resorption of P was incomplete. These
results indicate that resorption proficiency of K. obovata is less
sensitive than resorption efficiency to nutrient availability, and the
positive response of N resorption efficiency is related to the imbalance
of nutrient availability, while the positive response of P resorption
efficiency is unrelated to plant nutrient status. We suggest that
caution should be taken in using resorption efficiency of mangrove
species to predict plant nutrient status.