Forest stand- and age-structure-data for 80 transects sampled within the Squaretop Mountain and
Williams Creek study areas of the San Juan Mountains in southwestern Colorado, USA.
Source: Tepley and Veblen (2015).
Dataset description: Forest stand- and age-structure-data were collected across two ca. 1,340-ha study areas (Squaretop Mountain and Williams Creek) located within the San Juan National Forest of southwestern Colorado as part of a study to evaluate historical fire regimes and fire-driven forest dynamics across the moisture gradient of mixed-conifer and aspen forest. Stands were delineated using the “FSVEG_Spatial12212010” layer available from the San Juan National Forest
( http://www.fs.usda.gov/main/sanjuan/landmanagement/gis ) as a first approximation. Then stand boundaries were revised based on field reconnaissance and aerial photos, and stands smaller than 10 ha were aggregated into the more inclusive polygons.
Sampling was conducted in one, 160-m-long transect randomly located within each forest stand.
Altogether, 80 transects were sampled: 33 at Williams Creek and 47 at Squaretop Mountain. Each transect consists of 5, 0.04-ha (11.28 m radius) circular plots located at 40-m intervals between plot centers. Each plot includes two, concentric circular subplots.
Diameter at breast height (dbh) was recorded and an increment core from all live trees > 40 cm dbh throughout the entire plot and from trees 15 – 40 cm dbh in a 0.02-ha subplot (7.98-m radius) centered within the larger plot. Dbh was also recorded for all standing dead trees > 15 cm dbh, and an increment core was collected from trees killed by bark beetles within the preceding 5–10 years. Whenever we were unable to obtain an increment core to the pith due to heartrot, we cored trees of the same species and similar size outside of the plot until we were able to collect a sound core to the pith to use as a replacement for each tree with heartrot. In the smaller subplot (0.01 ha, 5.64-m radius), the number of tree and shrub stems 1.5–15.0 cm dbh was tallied by species.
Within the data file, a separate sheet is provided for each of the following datasets: (1) transect locations,
(2) overstory (> 15 cm dbh) species composition and size structure, (3) ages of overstory trees, (4) sapling
(1.5–15.0 cm dbh) density, (5) the forest type for each transect, and (6) codes for species used in the other datasheets.
Datafile: Tepley&Veblen2015_transect_data
How to cite:
Publications using these data should cite the original publication and the Dryad data package:
Tepley, A. J., and T. T. Veblen. 2015. Spatiotemporal fire dynamics in mixed-conifer and aspen forests in the San Juan Mountains of southwestern Colorado, USA. Ecological Monographs. dx.doi.org/10.1890/14-
1496.1.
Tepley, A. J., and T. T. Veblen. 2015. Data from Spatiotemporal fire dynamics in mixed-conifer and aspen forests in the San Juan Mountains of southwestern Colorado, USA. Dryad Digital Repository

SHEET 1: TransectLocation
– Each transect consists of five, 0.04-ha (11.28 m radius) circular plots at
40-m intervals between plot centers. This spreadsheet provides the location at the midpoint (the center of the third plot) of each of the 80 transects. Locations are provided in Universal Transverse Mercator
(UTM) coordinates (NAD83 zone 13N) and latitude and longitude coordinates (WGS84). Locations were determined in the field using a Garmin Oregon 550 handheld GPS receiver.
Attribute Name
Transect
Data Type Units
Text --
Easting
Description
Unique four-digit code (two letters followed by two numbers) for each of the 80 transects. The two letters indicate the study area (SM = Squaretop Mountain,
WC = Williams Creek). The numbers provide the number of the transect sampled within the respective study area. x-coordinate of the transect midpoint Integer m
Northing
Latitude
Longitude y-coordinate of the transect midpoint latitude of the transect midpoint longitude of the transect midpoint
Integer
Number
Number m
Decimal degrees
Decimal degrees

SHEET 2: Overstory – the dbh and status (living or dead) for all trees > 15 cm dbh sampled within 80 transects in the Squaretop Mountain and Williams Creek study areas. Sampling was conducted within 5,
0.04-ha circular plots per transect, where trees > 40 cm dbh were sampled across the entire area of each plot, and trees < 40 cm dbh were sampled in a 0.02-ha subplot (radius 7.98 m) centered within each larger plot. Each row of the spreadsheet provides data for one tree.
Attribute Name
Transect
Data Type Units
Text --
Description
Unique four-digit code (two letters followed by two numbers) for each of the 80 transects. The two letters indicate the study area (SM = Squaretop Mountain,
WC = Williams Creek). The numbers provide the number of the transect sampled within the respective study area.
Plot Integer --
SampleArea
SpCode
DBH
Plot number along each transect. Values range from
1 to 5.
Size of the circular subplot in which the tree was sampled. Trees > 40 cm dbh were sampled in the entire 0.04-ha plot (radius 11.28 m). Trees < 40 cm dbh were sampled in a 0.02-ha subplot (radius 7.98 m) centered within the larger plot.
Four-letter code representing the tree species. Codes are defined in the sheet titled “Species.”
Diameter at breast height (1.37 m)
Number
Text
Number ha
-- cm
Status Indicates whether the tree was alive or dead at the time of sampling.
Text --

SHEET 3: AgeStructure
– This sheet provides the dbh, status (living or dead), inner ring date, and pith date for each tree sampled in the 80 transects at Squaretop Mountain and Williams Creek. Data are included for all trees located within the plot for which we were able to obtain a core to the pith (or where the innermost ring forms a complete arc), plus trees located outside of the plot that were cored to provide replacement data for trees within the plot whenever we could not obtain a core to the pith due to heartrot.
Each row represents one tree.
Attribute Name
Transect
Data Type Units
Text --
Plot
SampleArea
SpCode
DBH
Description
Unique four-digit code (two letters followed by two numbers) for each of the 80 transects. The two letters indicate the study area (SM = Squaretop Mountain,
WC = Williams Creek). The numbers provide the number of the transect sampled within the respective study area.
Plot number along each transect. Values range from
1 to 5.
Size of the circular subplot in which the tree was sampled (values are either 0.04 or 0.02). Trees > 40 cm dbh were sampled in the entire 0.04-ha plot
(radius 11.28 m). Trees < 40 cm dbh were sampled in a 0.02-ha subplot (radius 7.98 m) centered within the larger plot. For trees sampled outside the plot, the sample area corresponds to that of the tree located within the plot that it replaces.
Four-letter code representing the tree species. Codes are defined in the sheet titled “Species”
Diameter at breast height (1.37 m)
Integer
Number
Text
Number
-- ha
-- cm
Status Text --
CoreNum
InnerRing
PithYr
OutOfPlot
Replaces
Notes
Indicates whether the tree was alive or dead at the time of sampling.
Core number. Cores were numbered sequentially within each plot of each transect. For example, plot 1 within transect SM01 has core numbers 1, 2, 3, and
4, and plot 2 within transect SM01 has core numbers
1, 2, 3, 4, 5, and 6.
Calendar year of the innermost ring of the core.
Calendar year at the pith. For cores that did not intersect the pith but the inner ring formed a complete arc, the number of years to the pith was estimated following Duncan (1989). Pith dates were not estimated for cores where the inner ring did not form a complete arc.
Indicates whether the tree was located within the plot or if it was located out of the plot and cored as a replacement for a tree with heartrot in the plot.
For trees located out of plot, this column provides the dbh of the tree within the plot for which this tree was cored as a replacement.
Additional information is provided where necessary to aid in interpreting the data.
Integer
Integer
Integer
Text
Number
Text
--
--
--
-- cm
--

SHEET 4: Saplings – the number of living stems for all woody plant species 1.5–15.0 cm dbh located within a 0.01-ha subplot (radius 5.64 m) centered within each of the 5 plots of the 80 transects. Each row of the spreadsheet provides data for one species within one of the five plots of each transect.
Attribute Name
Transect
Plot
SpCode
Description
Unique four-digit code (two letters followed by two numbers) for each of the 80 transects. The two letters indicate the study area (SM = Squaretop Mountain,
WC = Williams Creek). The numbers provide the number of the transect sampled within the respective study area.
Plot number along each transect. Values range from
1 to 5 within each transect.
Four-letter code representing the tree species. Codes are defined in the sheet titled “Species.” The code
“NONE” is used to indicate that no saplings were
Data Type Units
Text --
Integer
Text
--
--
NumStems recorded within a given subplot.
Number of stems 1.5–15.0 cm dbh recorded within the 0.01-ha (radius 5.64 m) subplot.
Integer --

SHEET 5: ForestType
– provides the forest type for each transect. We distinguished among four forest types by first determining whether aspen or the combination of spruce and subalpine fir accounted for
>50% of the overstory trees or >50% of the basal area. If so, those stands were classified as “Aspen” or
“Spruce-fir” stands, respectively. The remaining stands were mixed-conifer stands, which we classified as dry mixed-conifer (“DMC”) if ponderosa pine accounted for >10% of the basal area and ponderosa pine and Douglas-fir together comprised >25% of the basal area. Otherwise, they were labeled as moist mixed conifer (“MMC”).
Attribute Name
Transect
Data Type Units
Text --
ForestType
Description
Unique four-digit code (two letters followed by two numbers) for each of the 80 transects. The two letters indicate the study area (SM = Squaretop Mountain,
WC = Williams Creek). The numbers provide the number of the transect sampled within the respective study area.
Code representing the forest type of the sampled transect. Values are DMC, MMC, Aspen, or Sprucefir.
Text --
SHEET 6: Species – provides the four-letter code, along with the Latin name and common name for each species represented in the Overstory, AgeStructure, and Sapling datasets. Nomenclature follows the
Integrated Taxonomic Information System ( http://www.itis.gov/ ).
Attribute Name
SpCode
LatinName
Description
Four-letter code derived from the first two letters of the genus and the first two letters of the species.
Genus and species
Data Type Units
Text --
Text
CommonName Common name for each species Text --