Dataset consists of the annual aboveground net primary production (ANPP) across 3
habitats grouped by plant form and total ANPP. The habitats are grassland, mesquite
shrubland, and the ecotone between the 2. The plant forms are winter annual forb,
annual forb, bi-annual forb, perennial forb, annual grass, perennial grass, shrub, and
OBJECTIVE: The purpose of the study is to investigate how pulses of precipitation
translate into pulses of plant aboveground net primary productivity (NPP) and how the
small mammal community responds to such changes also in relation to shrub gradient
across the landscape. Particularly we are interested in how the energy flows through
the ecosystem in response to pulses of rain, how the small mammal community partition
resources (in terms of C3 (forbs and shrubs) and C4 (grasses) plants) and how the
genetic structure of some species (e.g., Dipodomys spp.) is affected by their
1) Small mammal abundance should respond positively to precipitation and NPP.
2) On a temporal scale, the small mammal energy use should show parallel fluxes along
the shrub gradient.
3) The small mammal community should consume C3 and C4 plants according to their
availability (or NPP).
4) At low population density, dispersal should be limited and the genetic variance will
be distributed among populations rather than within (i.e., Fst will trend towards
higher values). After pulses of rain and NPP, population densities will be greater,
dispersal prevalent, and the genetic variance of populations will be distributed within
populations (i.e., Fst will approach zero) as dispersal homogenizes populations.
Total aboveground annual net primary productivty is calculated for winter annual forb,
annual forb, bi-annual forb, perennial forb, annual grass, perennial grass, shrub,
sub-shrub, and the total of these.
Data file (CSV) for the Jornada dataset: Ecotone Study: Plant Above Ground Net Primary Productivity by Site
Summarizes mean aboveground net primary production, in g/m2/yr, by year for each of 15 sites. Annual totals derived by summing seasonal production values for winter (October - February), spring (February - May), and fall (May - October) increments for a single calendar year.
Please refer to these publications to evaluate the appropriateness of these data for your intended use prior to contacting Debra Peters, Responsible Investigator, with a data request.
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.
Attention: Data through 2003 was replaced online per below on 9/22/2011. Analyses and results for ANPP differ from previous uses of the data from 1989-1998 (Huenneke et al., 2002) in three ways: (1) Yucca elata was removed prior to analysis because its growth form results in large errors in biomass estimates from year-to-year, (2) regressions between biomass and plant volume used an intercept equal to 0 to be consistent with a recent study in a similar system (Muldavin et al., 2008), and (3) reference harvests obtained in extreme years resulted in adjusted regression coefficents through time that reflect year-to-year variation in ANPP. These changes result in ANPP values that are smaller compared (Peters et al. submitted) with previous studies (Huenneke et al., 2002).
These data sets contain calculated aboveground biomass values, by species, for each quadrat in each site for a given season. They are constructed (as outlined below) from the field data which are measurements of the physical dimensions (horizontal cover, vertical height) of plants or plant parts in the quadrats.
Objective is to monitor patterns (both temporal and spatial) of aboveground biomass across a range of ecosystem types; to allow the estimation of net primary production and its variability in those ecosystems; and to provide a quantitative description of plant community structure over time in those ecosystems.