Geography Research Seminar: Dr. Daniel Schillereff (King's College London), Exploring patterns and drivers of macronutrient stoichiometry in ombrotrophic peatlands
Decades of research here in the UK and abroad has confirmed that ombrotrophic peatlands across northern latitudes represent a globally-important store for carbon ©, nitrogen (N) and phosphorus (P) through the Holocene. That the supply of elements integral to biogeochemical functioning is largely controlled by external inputs is well-known but there is a striking dearth of long-term C, N and P stoichiometric data from ombrotrophic peatlands. As a result, some important questions surrounding the interactions between and controls on macronutrient cycling and accumulation remain unanswered. This precludes the production of long-term macronutrient inventories and introduces uncertainties into models of the global carbon cycle, for example.
In this seminar I will present results of some hypothesis testing, adapting the following structure:
(i) Preliminary estimates of millennial-scale macronutrient concentrations and accumulation rates in UK ombrotrophic peats and a global comparison;
(ii) That N and P concentrations in peat are strongly associated and P + MAP explains a substantial portion of variance in N;
(iii) That surface N and P enrichment peat is a distinctive feature of global peatlands that remains unconvincingly explained;
(iv) As recently shown for lakes, geochemical data hint at an anthropogenic alteration to atmospheric supply of N and P sourced from, for example, industrial aerosols and P-enriched dust. As P and N fixation influence rates of C fixation, such a mechanism would have major implications for long-term carbon accumulation;
(v) On-going and future plans to test this hypothesis more rigorously.
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