Assessing change in ecosystem processes twenty four years after the 1988 Yellowstone Wildfires, 2013

The extent of young postfire conifer forests is growing throughout western North America as the frequency and size of high-severity fires increase, making it important to understand ecosystem structure and function in early seral forests. Understanding nitrogen (N) dynamics during postfire stand development is especially important because northern conifers are often N limited. We re-sampled lodgepole pine (Pinus contorta var. latifolia) stands that regenerated naturally after the 1988 fires in Yellowstone National Park (Wyoming, USA) to ask: (1) How have N pools and fluxes changed over a decade (15 to 25 years postfire) of very rapid forest growth? (2) At postfire year 25, how do N pools and fluxes vary with lodgepole pine density and productivity? Lodgepole pine foliage, litter (annual litterfall, forest-floor litter), and mineral soils were sampled in 14 plots (0.25-ha) that varied in postfire lodgepole pine density (1,500 to 344,000 stems ha-1) and aboveground net primary production (ANPP; 1.4 to 16.1 Mg ha-1 yr-1). Previous data collected 15 and 17 years postfire (i.e., 2003 and 2005) provided a reference for assessing change in ecosystem process rates over time. At that time, lodgepole pine foliar nitrogen (N) concentrations had not yet suggested N limitation, and tree density and net primary production strongly influenced ecosystem carbon (C) and N stocks. These data were collected in 2012 and 2013 and are associated with the following publication: Turner, M. G., T. G. Whitby, and W. H. Romme. 2019. Feast not famine: Nitrogen pools recover rapidly in 25-yr old postfire lodgepole pine. Ecology (In press).