Seasonal aboveground plant biomass estimates at 15 net primary production (NPP) study sites at Jornada Basin LTER from 1989-ongoing

This data package contains aboveground vegetation cover, volume, and
calculated biomass values at the 15 Net Primary Production (NPP)
study sites on Jornada Experimental Range (JER) and Chihuahuan
Desert Rangeland Research Center (CDRRC) lands. Sites were selected
to represent the 5 major ecosystem types in the Chihuahuan Desert
(upland grasslands, playa grasslands, mesquite-dominated shrublands,
creosotebush-dominated shrublands, tarbush-dominated shrublands).
For each ecosystem type, three sites were selected to represent the
range in variability in production and plant diversity; thus the
locations are not replicates. At each site, a 1 hectare area was
fenced in 1988 and a grid of 49 (48 at one playa location) 1m x 1m
replicate quadrats was laid out when sampling began in 1989. For
each quadrat, aboveground biomass has been calculated from two data
sources: 1) non-destructive horizontal cover and vertical height
measurements of individual plants, or plant parts, within each
quadrat, and 2) linear regression coefficients for each plant
species derived from off-quadrat cover, height, and harvested
biomass measurements. Non-destructive measurements (1) are taken
during winter, spring, and fall measurement campaigns, then
aggregated by species for each quadrat, and resulting dimensions are
used to calculate species biomass (grams) by quadrat and season
using using the species-specific regression coefficients derived
from dataset 2. This is the most detailed biomass dataset available
and can be used to derive values of net primary production between
seasons or annually. Each dataset record contains calculated biomass
(and related variables) by species, quadrat, season, and site. Data
collection is ongoing with new observations in spring, fall, and
winter of each year, but this data package may be updated less
frequently. Attention: 1) For most species, these data are
not appropriate for estimates of percentage cover because of the way
the data are collected. 2) Calculated values in this data package
have changed over time as the methodology for estimating biomass has
changed. 3) Relating long-term NPP derived from this package with
long-term precipitation is problematic given the importance of wet
and dry periods and their effect on production in these ecosystems.
4) Data from 2013 and later are currently in provisional status and
subject to change as we review the allometric equations used for
estimating biomass. See Notes in the methods element for
further details.