In order to achieve the objectives of the project, MicroPEAT research programme involved two main components for each study region: an initial fieldwork to investigate local variability in terms of environmental conditions, microbial community structure and metabolism, and a later experiment to test drought effect on peat soil. During the first year of MicroPEAT project fieldwork in the Arctic and Wales was performed, samples from those sites were processed and drought experiment with Arctic peat cores was conducted. During the second year of the project, fieldwork in Colombia was concluded and drought experiments of Welsh and Colombian peat cores were developed together.
Requirements for field work and sample transport were checked in each study site before to make each field expedition, and corresponding administrative processes were conducted. Summarising, sampling in each region consisted of selecting six undisturbed peatlands sites dominated by mosses and, per triplicate, i) collecting peat cores of 5 x 100 cm and pore water, ii) measuring gas fluxes with static closed chambers, iii) measuring depth, temperature, pH, and conductivity. In the laboratory, an enzymatic profile, following natural layers in depth, was measured together with soil characteristics and metabolism. Soil microbial community, including Fungi, Bacteria, Archaea and Protozoa, of superficial soil layer is currently being assessed using specific primers.
Drought experiments consisted of four stages: i) an initial acclimation period, after extraction and transportation, of minimum 1 month; ii) then a pre-treatment period where all cores were kept waterlogged, around 2 months; iii) then 3 months of drought treatment; and, iv) 15 days of re-wetting. Enzyme activities and quality of pore water and gases emission were measured, as well as enzyme activities, chemistry and metabolism of peat soil. Currently, metagenomics of the microbial community from the experiments is being assessing.
MicroPEAT final results are not available yet but some general conclusions we have got so far are explained below. We have found remarkable differences in environmental characteristics (pH values, nutrients, and phenolic concentrations) among regions linked to variations in peat soil metabolism. For example, lignin degradation was particularly reduced in Wales, were lower pH value and higher phenol concentration were found, while degradation of cellulose and hemicellulose was quite constant among regions. Consequently, punctual gas emissions, measured in the field, suggest Welsh peatlands retain more carbon dioxide than Colombian and Arctic peatlands, but together with Colombian peatlands have more methane emissions (Fig. 2). Finally, preliminary analysis of the responses to drought from the three regions suggests that differential environmental and possibly microbial soil characteristics might are determining contrasting soil metabolism responses to drought. For example, lignin degradation seemed to be suppressed by drought in Colombia while not significant effect was observed in Wales and Arctic peat soil. Currently, several manuscripts are in preparation to disseminate MicroPEAT results.
