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

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.