Permanent forest plot data from 1982-2019 at Niwot Ridge, Colorado

The permanent forest plots at Niwot Ridge were installed in subalpine
forests in the Colorado Front Range by Dr. Thomas T. Veblen in the
early 1980s. The goal was to establish a set of long-term forest plots
to monitor tree populations and stand dynamics over time. Ten large
permanent plots (i.e., from 21 x 54m to 54 m x 54 m) were installed to
monitor ~ 400 trees per plot. An additional thirty smaller ‘gap’ plots
(i.e. approximately 10 m x 10 m) were installed in canopy openings
adjacent to three of the large permanent plots to monitor gap dynamics
(c. 40 trees per plot). Three new plots (42x42 m) were installed in
2016 (MRS11,13) or 2017 (MRS12) following the protocol for the large
permanent plots. The plots are located across gradients in elevation
and site moisture conditions. Plots include the following subalpine
tree species: lodgepole pine (“Pinus contorta”), limber pine (“Pinus
flexilis”), Engelmann spruce (“Picea engelmannii”), subalpine fir
(“Abies lasiocarpa”), and aspen (“Populus tremuloides”). When the
plots were installed, all living and standing dead trees were
permanently tagged, and the following was measured for all live and
dead trees less than 4 cm dbh: species, diameter at breast height (1.4
m), height class, and status (live or dead). Censuses of tree
mortality were conducted roughly every three years, except the period
1994-2007, and a complete re-measurement (e.g. dbh measurements) was
conducted in 2016 (see methods for details) and a status check
(live/dead) was conducted in 2019. Counts of juvenile trees (less than
4 cm dbh) by species were conducted when the plots were installed and
in 2017. This database includes three datasets: 1) description of
plots (e.g. elevation, aspect, size), 2) tree data (e.g. dbh, height
class, status) for all trees (greater than 4 cm dbh) monitored from
early 1980s to 2019, and 3) counts of juvenile trees (less than 4 cm)
by species in early 1980s and 2017.