The synergistic strategy of leaf nitrogen conservation and root nitrogen acquisition in an alpine coniferous forest along an elevation gradient

Abstract

Aims

Plant nitrogen (N) economics are largely determined by above-ground leaf conservation and below-ground root acquisition. Yet, how plants coordinate these two pathways under natural environmental gradients remains largely unknown.

Methods

Here, we investigated the coordination between leaf N conservation and root N acquisition strategies by analyzing leaf N fractions and resorption, root traits corresponding to nutrient acquisition, and environmental factors along an elevation gradient in an alpine coniferous forest (Abies georgei Orr). 

Results

Our results found a synergistic relationship between above-ground N conservation and below-ground N acquisition, driven by elevation-related variations in air temperature and soil N availability. Specifically, we found a decline in N conservation with increasing elevation, manifested by decreased N resorption efficiency and greater N allocation to structural construction. This decrease in N conservation coincided with a transition in root strategies from N conservation with denser roots and higher N mining to faster N acquisition characterized by high root N contents but diminished N mining as elevation rises.

Conclusions

Our results highlight the tight coupling between above- and below-ground nutrient conservation and acquisition across the complex environmental gradient, enhancing our understanding of plant strategy response to environmental change from a whole-plant perspective.