Seasonal reference harvest measurements of vegetation at 15 net primary production (NPP) study sites at Jornada Basin LTER, 1989-ongoing

This data package contains reference harvest measurements for the
long-term Net Primary Production (NPP) study at the Jornada Basin
LTER. Data here include horizontal cover, vertical height, and
aboveground biomass of plants harvested near, but outside, a grid of
permanent NPP quadrats at each of 15 NPP sites. These 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. All sites are
excluded from domestic grazing. Eleven sites are in non-grazed
pastures, and at the other four sites 1 hectare areas around the
observational plots were fenced in 1988. At all sites a grid of 49
(48 at one playa location) 1m x 1m replicate quadrats was laid out
when sampling began in 1989. Harvests are made outside the quadrat
grid, but inside the fence. Height and cover are recorded in the
field. Live biomass is weighed in the lab and all measurements are
recorded as reference harvest data. Subsequently, regressions
between the harvested biomass and plant volume values are used to
derive allometric equations that determine biomass from
non-destructive volume measurements in the permanent NPP quadrats.
Further details are described in the methods metadata. This is an
ongoing study with new harvest data (from selected species)
collected in the spring, fall, and winter each year. Attention: These data are not appropriate for
estimates of percentage cover because of the way the data are
collected.