LTER

This data set was collected to provide data for comparison of the losses of dissolved nitrogen and phosphorus in the runoff from grass- and shrub- dominated plots in the Jornada Basin of southern New Mexico. This dataset contains the following columns: Plot: the identification number for the plots, which are grouped for grass, shrub or intershrub areas. Fill Time: the time in seconds used to collect an individual sample of discharge from the plot. Time: the time in minutes (from the beginning of the rainfall simulation) at which each individual collection of discharge began. In each case, the first time listed is the time at which discharge was first observed. Time b/w samples: the time in seconds between the beginning the collection of a given sample of discharge and the beginning of the next collection. Q: the rate of discharge during each collection, in cubic centimeters per second. AveQ/time: the total discharge during an interval in cubic centimeters. For example, the discharge between 16 and 20 minutes is calculated as the mean of the discharge at l6 and 20 minutes multiplied by 4 minutes. InorgN-rain (adjusted inorganic N): the concentration of NH4-N + NO3-N in the discharge sample collected, corrected for the sum of the concentration of these ions in the simulated rainfall applied. Concentration is given in milligrams per liter for N contained in the sum of these forms. Analysis for NH4-N and NO3-N was performed using the Bran-Luebbe Traacs 800 Autoanalyzer, as detailed in Schlesinger et al. (l999). Total N-rain (adjusted total N): the concentration of total dissolved N in the discharge sample collected, corrected for the concentration of total dissolved N in the simulated rainfall applied. Concentration is given in milligrams per liter of total dissolved N in the sample. The concentration of total dissolved N was performed using the Traacs 800 Autoanalyzer, following a persulfate digestion of the sample, as detailed in Schlesinger et al. (l999). OrgN-rain (adjusted organic N): the concentration of N contained in dissolved organic forms, corrected for the concentration of dissolved organic N in the simulated rainfall applied. Dissolved organic N is calculated as the difference, in any sample, between the total dissolved N and the sum of NH4-N and NO3-N. Values are in milligrams per liter. Total P-rain (adjusted total P): the concentration of total dissolved phosphorus, corrected for the concentration of total dissolved phosphorus in the simulated rainfall applied, both in milligrams per liter. Org-P-rain (adjusted org P): the concentration of dissolved organic phosphorus, corrected for the concentration of dissolved organic phosphorus in the simulated rainfall applied, both in milligrams per liter. Inorg-N-rain (adjusted inorganic N), the yield in grams of NH4-N plus NO3-N in the discharge collected. TotalN-rain (adjusted total N), the yield in grams of total dissolved N in the discharge collected. OrgN-rain (adjusted organic N), the yield in grams of forms of dissolved organic N in the discharge collected. Total P-rain (adjusted total P), the yield in grams of total dissolved phosphorus in the discharge collected. OrgP-rain (adjusted organic P), the yield in grams of forms of dissolved organic phosphorus in the discharge collected. InorgN-rain (adjusted inorganic N) load, is the rate of loss, in grams per second, of the sum of NH4-N plus NO3-N during the period of the sample collection. Total N-rain (adjusted total N) load, is the rate of loss, in grams per second, of total dissolved N during the period of the sample collection. OrgN-rain (adjusted organic N) load, is the rate of loss, in grams per second, of dissolved organic N during the period of the sample collection. Total P-rain (adjusted total P) load, is the rate of loss, in grams per second, of total dissolved P during the period of the sample collection. Org-P-rain (adjusted organic P) load, is the rate of loss, in grams per second, of dissolved organic P during the period of the sample collection.

Monthly total of pan evaporation data collected daily from standard U.S. climatological service instruments located at USDA Jornada Experimental Range Headquarters.

In 1933 and 1935, two transects were established in the Natural Revegetation Exclosure and Pasture 8b, respectively, to measure long-term soil movement in areas undergoing mesquite invasion. These two transects, established in a Prosopis-Bouteloua ecotone, were to: "measure any future changes in the extent or succession of three contiguous zones of vegetation, Bouteloua eriopoda, Gutierrezia, and Prosopis glandulosa dunes. Thus, future chartings of this transect should show whether, under the range management practiced, the succession is progressing toward the black grama climax or whether it is retrogressing toward mesquite sandhills." (E.L. Little, 1935, unpublished report) Soil movement at these transects was measured by the distance between the soil surface and a notch in 50 cm t-posts located every 15.2 m (50 ft). The 1731-m Natural Revegetation Exclosure tranect runs north-south through the center of the exclosure and extends 61 m (200ft) beyond the boundary fence on either end. It is located in primarily deep, loamy sand soils. The 457-m Pasture 8b transect is oriented WSW-ENE, and is located in shallower soils. These transects were measured in 1950 (8b only), 1955 (8b only), every five years from 1980-2000, and most recently in 2011. Most steel posts were remeasured at these intervals, but some were lost due to excavation or burial. These were for the most part replaced, with a new baseline notch height initiated on the posts. Data fields correspond to each year of collection, as well as measures of soil deposition or deflation during the intervals. Spatial data include post locations and identifiers.

   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
   sub-shrub.

   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
   population dynamics.

   HYPOTHESES:

   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.
 

   OBJECTIVE:  The purpose of the study is to investigate how pulses of precipitation translate into
   pulses of plant above ground 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 (i.e.:  Dipodomys spp.) is
   affected by their population dynamics.

   HYPOTHESES:
   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.

   Variables include rodent species, sex, reproductive status, weight, and maturity status were recorded.