Wildfires and geochemical change in a subalpine forest over the past six millennia

Citation: Bérangère Leys and Philip E Higuera and Kendra K McLauchlan and Paul V Dunnette. (2016). Wildfires and geochemical change in a subalpine forest over the past six millennia. Environmental Research Letters, 11(12), 125003.Bérangère Leys and Philip E Higuera and Kendra K McLauchlan and Paul V Dunnette. (2016). Wildfires and geochemical change in a subalpine forest over the past six millennia. Environmental Research Letters, 11(12), 125003.The frequency of large wildfires in western North America has been increasing in recent decades, yet the geochemical impacts of these events are poorly understood. The multidecadal timescales of both disturbance-regime variability and ecosystem responses make it challenging to study the effects of fire on terrestrial nutrient cycling. Nonetheless, disturbance-mediated changes in nutrient concentrations could ultimately limit forest productivity over centennial to millennial time scales. Here, we use a novel approach that combines quantitative elemental analysis of lake sediments using x-ray fluorescence to assess the geochemical impacts of high-severity fires in a 6200 year long sedimentary record from a small subalpine lake in Rocky Mountain National Park, Colorado, USA. Immediately after 17 high-severity fires, the sedimentary concentrations of five elements increased (Ti, Ca, K, Al, and P), but returned to pre-fire levels within three decades. Multivariate analyses indicate that erosion of weathered mineral material from the catchment is a primary mechanism though which high-severity fires impact element cycling. A longer-term trend in sediment geochemistry was also identified over millennial time scales. This decrease in the concentrations of six elements (Al, Si, K, Ti, Mn, and Fe) over the past 6200 years may have been due to a decreased rate of high-severity fires, long-term ecosystem development, or changes in precipitation regime. Our results indicate that high-severity fire events can determine elemental concentrations in subalpine forests. The degree of variability in geochemical response across time scales suggests that shifting rates of high-severity burning can cause significant changes in key rock-derived nutrients. To our knowledge, these results are the first to reveal repeated loss of rock-derived nutrients from the terrestrial ecosystem due to high-severity fires. Understanding the future of fire-prone coniferous forests requires further documentation and quantification of this important mechanism linking fire regimes and biogeochemical cycles

Data, code, and figures from Dunnette et al. 2014, Biogeochemical impacts of wildfires over four millennia in a Rocky Mountain subalpine watershed. New Phytologist. 203: 900-912 (doi: 10.1111/nph.12828)

<p>SEE README.pdf OR README.md</p> <p> </p> <p>This archive includes data and scripts needed to reproduce the analyses in Dunnette et al. 2014; it includes 49 files and is 23 MB when downloaded as a .zip archive. After extracting the .zip archive, sort by file type. Most data files are in .csv format, while some are in .xls format. Scripts and functions are written for MATLAB software (*.m file type; www.mathworks.com), and each file is fully commented, including dependencies. For some scripts or functions, the MATLAB statistics or curve fitting toolbox is required; all other functions required are provided in this archive.</p> <p> </p> <p>Dunnette, P.V., P.E. Higuera, K.K. McLauchlan, K.M. Derr, C.E. Briles, and M.H. Keefe. 2014. Biogeochemical impacts of wildfires over four millennia in a Rocky Mountain<br>subalpine watershed. New Phytologist In Press doi: 10.1111/nph.12828</p> <p> </p> <p> </p

Biogeochemical response to fire over six millennia in a Rocky Mountain subalpine forest. 98th Annual Meeting of the Ecological Society of America, Minneapolis, MN.

<p>Poster from 2013 Ecological Society of America Meeting. Please cite the following for poster use: </p> <p>Dunnette, P. V., P. E. Higuera, and K. M. Derr. 2013. Biogeochemical response to fire over six millennia in a Rocky Mountain subalpine forest. 98th Annual Meeting of the Ecological Society of America, Minneapolis, MN.</p> <p> </p> <p>This work has sense been published in the following paper: </p> <p>Dunnette, P. V., P. E. Higuera, K. K. McLauchlan, K. M. Derr, C. E. Briles, and M. H. Keefe. 2014. Biogeochemical impacts of wildfires over four millennia in a Rocky Mountain subalpine watershed. New Phytologist 203:900-912.</p