AUTHOR=Stuart Jason M. , Anderson Russell , Lazzarino Patrick , Kuehn Kevin A. , Harvey Omar R. 

TITLE=Physical Processes Dictate Early Biogeochemical Dynamics of Soil Pyrogenic Organic Matter in a Subtropical Forest Ecosystem

JOURNAL=Frontiers in Earth Science

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2018.00052

DOI=10.3389/feart.2018.00052

ISSN=2296-6463

ABSTRACT=<p>Quantifying links between <italic>py</italic>OM dynamics, environmental factors and processes is central to predicting ecosystem function and response to future perturbations. In this study, changes in carbon (<italic>TC</italic>), nitrogen (<italic>TN</italic>), pH, and relative recalcitrance (<italic>R</italic><sub><italic>50</italic></sub>) for pine- and cordgrass-derived <italic>py</italic>OM were measured at 3–6 weeks intervals throughout the first year of burial in the soil. Objectives were to (1) identify key environmental factors and processes driving early-stage <italic>py</italic>OM dynamics, and (2) develop quantitative relationships between environmental factors and observed changes in <italic>py</italic>OM properties. The study was conducted in sandy soils of a forested ecosystem within the Longleaf pine range of the United States with a focus on links between changes in <italic>py</italic>OM properties, fire history (<italic>FH</italic>), cumulative precipitation (<italic>P</italic><sub><italic>cum</italic></sub>), average temperature (<italic>T</italic><sub><italic>avg</italic></sub>) and soil residence time (<italic>SRT</italic>). <italic>P</italic><sub><italic>cum</italic></sub>, <italic>SRT</italic> and <italic>T</italic><sub><italic>avg</italic></sub> were the main factors controlling TC and TN accounting for 77–91% and 64–96% of their respective variability. Fire history, along with <italic>P</italic><sub><italic>cum</italic></sub>, <italic>SRT</italic> and <italic>T</italic><sub><italic>avg</italic></sub>, exhibited significant controlling effects on <italic>py</italic>OM pH and <italic>R</italic><sub><italic>50</italic></sub>—accounting for 48–91% and 88–93% of respective variability. Volatilization of volatiles and leaching of water-soluble components (in summer) and the sorption of exogenous organic matter (fall through spring) were most plausibly controlling <italic>py</italic>OM dynamics in this study. Overall, our results point to climatic and land management factors and physicochemical process as the main drivers of <italic>py</italic>OM dynamics in the pine ecosystems of the Southeastern US.</p>