Nitrogen homeostasis and use strategies: Implications for the success of trees with ectomycorrhizal associations in nitrogen-limited temperate forests

Abstract

Plant stoichiometric homeostasis and nutrient use strategies are strongly associated with their potential to achieve dominance in nutrient-poor habitats. EcM-associated tree species are more abundant than AM-associated species in nitrogen (N) impoverished temperate forests. However, we lack an in-depth understanding of how stoichiometric homeostasis and nutrient use strategies of AM and EcM tree species affect their dominance in N-limited forest ecosystems. Here we examined the differences in stoichiometric homeostasis of N, N use strategies (N resorption efficiency (NRE) and leaf C:N ratios), and abundance between AM and EcM tree species, and further assessed whether the causal relationships among stoichiometric homeostasis, nutrient use strategies, and abundance differed between AM and EcM tree species across four successional stages of a mixed broadleaved–Korean pine (Pinus koraiensis) forest. EcM tree species showed a higher stoichiometric homeostasis of N, NRE, leaf C:N ratios, and abundance than did AM tree species at four successional stages. Meanwhile, the NRE and leaf C:N ratios of EcM tree species were mainly governed by stoichiometric homeostasis of N; however, they were more influenced by soil inorganic N in AM tree species. Finally, N use strategies of AM and EcM plants significantly affected their abundance. Our results contribute to a better understanding of the causes of the distribution patterns of different tree mycorrhizal associations in nature and offer guidance for forest management practices by highlighting the role of EcM plants with higher N homeostasis in sustaining long-term nutrient balance.