Several long-term studies at the Sevilleta LTER measure net primary production (NPP) across ecosystems and treatments. Net primary production is a fundamental ecological variable that quantifies rates of carbon consumption and fixation. Estimates of NPP are important in understanding energy flow at a community level as well as spatial and temporal responses to a range of ecological processes. The NPP weight data (SEV 157) is obtained by harvesting a series of covers for species observed during plot sampling. These species are always harvested from habitat comparable to the plots in which they were recorded. This data is then used to make volumetric measurements of species and build regressions correlating biomass and volume. From these calculations, seasonal biomass and seasonal and annual NPP are determined. These sampled are then vouchered for use to do analyses of inorganic and organic components such as carbon, nitrogen, and phosphorous as well as and other macro and micro nutrients and organic components such as cellulose and lignin.
After all aboveground net primary production (ANPP) quadrat measurements are complete, plants of similar size classes are harvested outside the permanent quadrats. These samples are sorted, dried, and weighed and the resulting data (weight dataset- SEV157) is used to create regressions that estimate aboveground biomass. Then the harvest samples of all size classes, for each species, are then combined to make a voucher sample. A subsample of that combined sample is then ground up mechanically and stored in a sealed glass vial. These samples are available for quantitative chemical analysis of their inorganic and organic composition. Seasonal as well as inter-annual compositions of the various species on the Sevilleta can be derived from this material. The samples are stored at the Sevilleta Field Station. Please contact Stephanie Baker for sample access.