Drivers of understory plant communities in Sierra Nevada mixed conifer forests with pyrodiversity

Fire Ecology

Table 1 Data sources for explanatory and response variables, the source, and the scale at which they were collected in the Illilouette Creek basin in Yosemite National Park and Sugarloaf Valley in Kings Canyon National Park, California, USA. Public data were collected from early 1900s. Study data were collected from 2002 to 2013. Field data were collected from 2002 to 2013 to observe naturally occurring patterns of forest and understory structure and composition in relationship to fire regime

Variables		Source	Resolution
Understory community response variables
Percent cover		Point-intercept of understory 0 to 2 m² and timed area search	490 m²
Richness		Timed-area search	490 m²
Evenness		Point-intercept of understory 0 to 2 m² and timed area search	490 m²
Simpson’s diversity		Point-intercept of understory 0 to 2 m² and timed area search	490 m²
Explanatory variables
Fire	Time since fire	Sequoia-Kings National Park 2012; Yosemite National Park 2012	Varied^a
	Fire severity	Miller and Thode 2007	30 m²
	Number of times burned	Miller and Thode 2007	30 m²
	Pyrodiversity	Miller and Thode, Sequoia-Kings National Park 2012; Yosemite National Park 2012	30 m²
Environmental	Shrub cover	Point-intercept of shrubs 0.5 to 2 m²	490 m²
	Percent slope	Clinometer	490 m²
	Canopy cover	GRS tube densitometer	490 m²
	Soil texture	Thien 1979	490 m²
	Litter depth	Average of six measurements	490 m²
	Elevation	USGS Digital Elevation Model from Gesch 2007	10 m²
	Solar radiation	Derived from USGS Digital Elevation Model following McCune and Keon 2002	100 m²
	Climatic water deficit	Flint et al. 2014	270 m²

^aTime since fire is “varied” since the records go back to early 1900s. Excerpt from metadata: “This coverage represents the YOSE fire history from 1930 through 2018. Original data was interpreted from historical fire records held at Yosemite National Park in the late 1980s. GRASS data was converted to Arc/Info coverage format when Yosemite migrated to Arc/Info in 1995. Some vector data was lost in conversion from GRASS. In those instances, polygons were vectorized from raster versions that remained in GRASS. Each year from 1995 to 2000, fires were input into Arc/Info by digitizing 1:24,000 USGS paper maps (7.5″ series) or from Trimble GPS readings. Starting 2001, all larger fire perimeters were acquired through ground GPS or helicopter GPS reconnaissance. Small fire point locations were acquired through ground GPS or helicopter GPS and buffered to approximate fire size”