Enhanced plant leaf P and unchanged soil P stocks after a quarter century of warming in the arctic tundra
Authors
McLaren J.R., Buckeridge K.M.
Reference
Ecosphere, vol. 12, n° 11, art. no. e03838, 2021
Description
Phosphorus (P) limits or co-limits plant and microbial life in multiple ecosystems, including the arctic tundra. Although current global carbon (C) models focus on the coupling between soil nitrogen (N) and C, ecosystem P response to climate warming may also influence the global C cycle. Permafrost soils may see enhanced or reduced P availability under climate warming through multiple mechanisms including changing litter inputs through plant community change, changing plant–microbial dynamics, altered rates of mineralization of soil organic P through increased microbial activity, and newly exposed mineral-bound P via deeper thaw. We investigated the effect of long-term warming on plant leaf, multiple soil and microbial C, N, and P pools, and microbial extracellular enzyme activities, in Alaskan tundra plots underlain by permafrost. Here, we show that 25 yr of experimental summer warming increases community-level plant leaf P through changing community composition to favour relatively P-rich plant species. However, despite associated increases in P-rich litter inputs, we found only a few responses in the belowground pools of P available for plant and microbial uptake, including a weak positive response for citric acid–extractable PO4 in the surface soil, a decrease in microbial biomass P, and no change in soil P (or C or N) stocks. This weak, neutral, or negative belowground P response to warming despite enhanced litter P inputs is consistent with a growing number of studies in the arctic tundra that find no long-term response of soil C and N stocks to warming.
