Nitrogen addition impacts on soil microbial stoichiometry are driven by changes in plant resource stoichiometry not by the composition of main microbial groups in an alpine meadow.

Liu, Xiaochen; Lamb, Eric G.; Zhang, Shiting

Increased nitrogen (N) inputs and subsequent effects on soil microbial stoichiometry have strong influences on organic matter decomposition and nutrient cycling. The effects of N addition on soil microbial stoichiometry are well documented, but we know little about the mechanisms linking between N addition and soil microbial stoichiometry. We examined how the effects of N addition cascade through soil properties (pH, available N (AN), available phosphorus (AP), dissolved organic carbon (DOC), DOC/AN, AN/AP and DOC/AP ratios), plant community composition (grasses, sedges, forbs, and legumes), plant resource stoichiometry (community-level leaf and root C/N/P ratios), and the composition of main microbial groups (phospholipid fatty acids profile) to influence microbial stoichiometry using a 5-year N fertilization field experiment in a Tibetan alpine meadow. We found that N addition changed soil microbial C/N and N/P ratios, but not microbial C/P ratios, indicating plasticity in microbial stoichiometry to increasing N deposition. Moreover, the changes in microbial stoichiometry were driven by N not C and P concentrations. Structural equation modeling revealed that N addition predominantly controlled soil microbial C/N and N/P ratios through plant leaf and root stoichiometry, but not the composition of plant community and main microbial groups. Our findings suggest that N addition-induced changes in plant resource stoichiometry are the core drivers of soil microbial stoichiometry responses to N deposition.

MOUNTAIN meadows; STOICHIOMETRY; PLATEAUS; STRUCTURAL equation modeling; NUTRIENT cycles; SOILS

Biology & Fertility of Soils, 2020, Vol 56, Issue 2, p261

0178-2762

Academic Journal

10.1007/s00374-019-01423-1