NPP Study: Quadrat field measurement data

Standing biomass is sampled three times
a year: in winter (February - March), before shrubs begin
spring growth; in spring (May), when shrubs and spring
annuals have reached peak biomass; in fall (late summer;
October), when summer annuals have reached peak biomass but
before killing frosts. At each sample date, each site is
visited (order of sampling may vary, according to
phenological stage of sites) and the dimensions of each
plant on each quadrat are measured and recorded. Recorded
for each observation are: date, zone, plot, quadrat #,
species (4 letter acronym), observation # (one for each
measurement of that species in that quadrat), cover
(percentage of quadrat covered by canopy of that individual
or species), height (vertical extent of that individual or
species), count (if multiple individuals with the same
dimensions are present), and phenological stage
(Flowering/fruiting or Vegetative).
Attention: These data are not appropriate for estimates of percentage cover. NPP-associated percent cover measurements were developed for and are used solely to provide the best estimate of biomass production. Becuase the methodology results in measurements of overlapping subcanopy systems and canopies of adjacent individuals, NPP percent cover measurements are not an appropriate measure of actual aerial plant cover. Doing so will result in inflated numbers for the "actual" vegetative cover.