Laguna_conifer_data.xls

Information
regarding study areas and data collection (from Freeman et al. 2017)

Title:
Patterns of mortality in a montane mixed-conifer forest in San Diego County,
California

Study
Area

We analyze tree mortality within
the montane mixed-conifer forests of San Diego County, which occur as
ecological “islands” and are found on Palomar Mountain, in the greater Julian
area, including Harrison Park, Cuyamaca, Laguna Mountain, Descanso and Pine
Valley, and in the Lost Valley area near Warner Spring (see table for specific
study area locations). These sites were chosen to represent the variety of
physical site characteristics and species diversity that are present in the
montane areas of the County. Site 1 (1260 ha) extends from the Fry Creek
Campground area to Palomar State Park on Palomar mountain, , and is comprised
of Sierran mixed coniferous forest (white fir, incense cedar, Big cone Douglas
fir, and Coulter pine), at an elevation of 1500 m. Site 2 (950 ha) is located
in the Volcan Mountain Preserve (administered by the San Diego County Parks and
Recreation Department) just north of the town of Julian and consists of
scattered groves of mostly incense cedar, with smaller amounts of Big cone
Douglas fir and Coulter pine on the upper slopes of the West side of the
mountains (peak elevation of 1743 m). Site 3 (3000 ha) is located on Laguna
mountain (part of the U.S. Forest Service Descanso District), peak elevation of
1800 m, which is almost exclusively covered by Jeffrey pine forest.

Field surveys

We obtained permits and conducted field surveys during the
summer of 2008 to determine forest stand structure, mortality conditions, and
affected conifer species in the three study areas. Surveys were based on a
stratified random sample of 20 m radius circular plots for each study area. We excluded logged and recent burn areas from
the surveys, to constrain the analysis to mortality agents other than fire or
thinning. Prior to fieldwork in
2008, around 80 ha had burned in the NW corner of the Volcan study area and
around 30 ha had burned in the central northernmost edge of the Laguna study
area. In October of 2007 the Poomacha Fire burned around 20 ha in the NW corner
of the Palomar study area, as well as an additional 160 ha in the SW corner. Post
fire there was extensive thinning and mulching of about 50 ha in the Fry Creek
Campground area and along the roads in the NE corner of the study area. Data
collected in these plots included a census of tree species, health condition of
live trees, agents of mortality if possible for dead trees, and dbh by species.
We positionally surveyed the centers of the plots using a GPS (see table). We
surveyed 20 plots within the Palomar and Laguna Mountain study areas, and 10
plots for Volcan Mountain. We analyzed forest stand data to determine stand
density, and basal area by species for both live and dead trees, as well as
which tree species and which size-class distributions had the most mortality.