Boreal forest floor greenhouse gas emissions across a wildfire-disturbed chronosequence

Data collected during field experiments to investigate the effect of wildfires on greenhouse gas emissions across forests of differing ages in Sweden. Data comprise greenhouse gas measurements, soil horizon depth, bulk density, loss on ignition, pH, soil phosphorus, carbon and nitrogen, plant species cover, air temperature, soil temperature, soil moisture and surface leaf moisture. Greenhouse gas measurements were taken in the field. Soil cores were collected, then processed and analysed in the laboratory. Plant species cover was by visual estimate and final plant biomass was collected, dried, and weighed. Weather stations were used to collect temperature and moisture data. Data were collected from six Swedish boreal forest sites forming a chronosequence ranging in age from approximately 45 to 365 years since last wildfire. This part of the project used soil and plant property data, climatic data, and age since wildfire to investigate controls on forest floor greenhouse gas fluxes. The project ran from 2012 to 2015.

Field data was collected in June and September 2012, June 2013, and July 2014. Greenhouse gas fluxes were measured using infrared gas analysers (PP Systems EGM4) for CO2 and manual samples from static chambers for CH4 and N2O, which were analysed on a gas chromatogram (PerkinElmer Autosystem XL). Data were quality controlled by plotting all data points and removing any points showing signs of the system not being settled or properly sealed. Calibration standards were used for both systems. At the time of sampling, measures of air temperature and photosynthetically active radiation were taken using a temperature probe (TinyTag) and PAR Quantum Sensor (Skye Instruments), respectively.

Soil cores were collected either along a transect or from within the gas collars. Cores were PVC pipes of 5 cm diameter and 10 cm length. Manual processing (including oven-drying of samples) gave values for soil horizon depths, bulk density, and loss on ignition. pH was determined by mixing 10 g fresh soil in 25 mL deionized water and measuring using a pH probe (Hanna Instruments). Total phosphorous was obtained using a digestion method with analysis on a SEAL AutoAnalyser3 (Seal Analytical). Total C:N was obtained by analysing samples on a Truspec C:N analyser (LECO Corp.). Instruments were run with calibrated standards.

Estimates of cover by individual plant species were made visually and photos were used for quality control. Plant material was collected from within the gas collars, dried at 60ºC, and weighed for total biomass.

Air temperature, soil temperature at 1 cm and 5 cm depth, soil moisture, and surface leaf moisture were measured using weather stations (Decagon Devices). Data was plotted to quality control for errors caused by dead batteries, snow cover, etc.

Mason, K.E.; Oakley, S.; Street, L.E.; Arróniz-Crespo, M.; Jones, D.L.; DeLuca, T.H.; Ostle, N.J. (2017). Boreal forest floor greenhouse gas emissions across a wildfire-disturbed chronosequence. NERC Environmental Information Data Centre. https://doi.org/10.5285/f08a5de5-55d4-44de-90e1-94bb4f814054