Leaf enzyme plays a more important role in leaf nitrogen resorption efficiency than soil properties along an elevation gradient

1. Nitrogen (N) resorption is a strategy for plant N conservation through which plants withdraw N from senescing leaves prior to litterfall and its underlying mechanisms are important for better understanding of N cycling. However, most current studies focused on the impacts of soil and leaf nutrients on leaf N resorption efficiency (NRE), and plant physiological regulation that is species-dependent is still unclear.
2. Here, we conducted a field experiment to investigate the variations of leaf NRE along an altitudinal gradient in a temperate forest of Northeastern China.
3. Results showed that leaf NRE of Q. mongolica and F. mandshurica increased with altitude, while leaf NRE of T. amurensis, A. mono and A. pseudosieboldianum exhibited an opposite trend, although the relationships were not significant for F. mandshurica and A. mono. The inconsistent responses of leaf NRE of different species to increasing altitude were primarily due to the effect of leaf Glutamate dehydrogenase (GDH), ...