Phosphorus additions imbalance terrestrial ecosystem C:N:P stoichiometry.

ABSTRACT

Carbon (C)nitrogen (N)phosphorus (P) stoichiometry in plants, soils, and microbial biomass influences productivity and nutrient cycling in terrestrial ecosystems. Anthropogenic inputs of P to ecosystems are increasing; however, our understanding of the impacts of P addition on terrestrial ecosystem CNP ratios remains elusive. By conducting a meta-analysis with 1413 paired observations from 121 publications, we showed that P addition significantly decreased plant, soil, and microbial biomass NP and CP ratios, but had negligible effects on CN ratios. The reductions in NP and CP ratios became more evident as the P application rates and experimental duration increased. The P addition effects on terrestrial ecosystem CNP stoichiometry did not vary with ecosystem types or climates. Moreover, the responses of NP and CP ratios in soil and microbial biomass were associated with the responses of soil pH and fungibacteria ratios. Additionally, P additions increased net primary productivity, microbial biomass, soil respiration, N mineralization, and N nitrification, but decreased ammonium and nitrate contents. Decreases in plant NP and CP ratios were both negatively correlated to net primary productivity and soil respiration, but positively correlated to ammonium and nitrate contents; microbial biomass, soil respiration, ammonium contents, and nitrate contents all increased with declining soil NP and CP ratios. Our findings highlight that P additions could imbalance CNP stoichiometry and potentially impact the terrestrial ecosystem functions.