LTAR

USDA-ARS Long-Term Agroecosystem Research Network (https://www.tucson.ars.ag.gov/ltar)

Dataset: 

Study number: 

381

Data set ID: 

210381001

Abstract: 

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.

Data sources: 

data_JornadaStudy_381_nutrient_loss_nitrogen_phosphorous_chemistry

LTER Core Area(s): 

Dataset: 

Study number: 

38

Data set ID: 

210038001

Abstract: 

This ongoing dataset contains monthly precipitation measurements from a network of standard can rain gauges at the Jornada Experimental Range in Dona Ana County, New Mexico, USA. Precipitation physically collects within gauges during the month and is manually measured with a graduated cylinder at the end of each month. This network is maintained by USDA Agicultural Research Service personnel. This dataset includes 39 different locations but only 29 of them are currently sampled. Other precipitation data exist for this area, including event-based tipping bucket data with timestamps, but do not go as far back in time as this dataset.

Data sources: 

data_JornadaStudy_380_jer_standard_raingage_data

LTER Core Area(s): 

Keywords: 

Dataset: 

Study number: 

37

Data set ID: 

210379003

Abstract: 

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

Data sources: 

data_JornadaStudy_379_noaa_weather_station_evaporation_pan_monthly

LTER Core Area(s): 

Dataset: 

Study number: 

37

Data set ID: 

210379002

Abstract: 

Monthly summary of precipitation and air temperature data collected daily from standard U.S. climatological service instruments located at USDA Jornada Experimental Range Headquarters.

Data sources: 

data_JornadaStudy_379_noaa_weather_station_climate_monthly

LTER Core Area(s): 

Keywords: 

Dataset: 

Study number: 

39

Data set ID: 

210392001

Abstract: 

The purpose of this study is to quantify vegetation dynamics in response to lagomorph and shrub exclusion. Data consist of vertical line intercept measures of the perennial grasses, suffretescents and shrubs. Sixteen plots at each of 3 sites (Gravelly Ridges, Dona Ana exclosure, and Parker Tank) were established in 1938-39 by Ken Valentine. Plots were 21.3 x 21.3 m in 4 rows of 4 plots with a 7.6 m buffer zone. All plots were sampled before treatments. Plots were divided into east and west halves and 14 randomly located 10.65 m transects were located in each half plot. Vegetation (black grama, dropseeds, bush muhly, fluff grass, other grasses, creosotebush, honey mesquite, tarbush, mariola, and other shrubs) was measured using vertical line point intercepts. Plots have been re-read in 1947, 1956, 1960, 1967, 1989, 1995, and 2001 for Gravelly Ridges and 1939, 1947, 1960, 1967, and 2001 for Dona Ana and Parker Tank using the same methods. Treatments were applied factorially yielding a control plot, single factor plots, and plots with varying degrees of combinations of factors. The factors were lagomorph exclusion (using wire fencing), shrub removal (hand grubbing at the ground surface), furrowing (shallow, hand raked furrows to trap surface water), and seeding (broadcast applications of seeds of native perennials). Seeding and furrowing treatments were only applied in 1939. Lagomorph exclusion has persisted since establishment, and shrub removal treatments have been reapplied immediately following all years of vegetation sampling. This study is complete.

For more information, refer to:

Havstad, K.M., R.P. Gibbens, C.A. Knorr, and L.W. Murray. 1999. Long-term influences of shrub removal and lagomorph exclusion on Chihuhuan Desert vegetation dynamics. Journal of Arid Environments 42: 155-166.

 

Data sources: 

JornadaStudy_392_lagomorph_creosotebush_plot_data

LTER Core Area(s): 

Dataset: 

Study number: 

36

Data set ID: 

210365001

Abstract: 

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.

Data sources: 

data_JornadaStudy_365_longterm_soil_movement_across_ecotones_since_1933

LTER Core Area(s): 

Dataset: 

Study number: 

28

Data set ID: 

210288001

Abstract: 

Collections of airborne sand are obtained at the 15 NPP sites and the Geomet site. The collections are taken using BSNE collectors. The collectors are turned into the wind with wind vanes. The amount of material collected corresponds to the horizontal flux at the height of the collector and the opening area of the collector and the duration of the sampling time. The five heights of the BSNE collectors above the soil surface are 5, 10, 20, 50, and 100 centimeters for every location where samples are taken. The hypothesis of the experiment is that the vertical flux of the particles smaller than 10 micrometers is a constant ratio of the horizontal sand flux. The objectives of the experiment are to find patterns of sand flux rates as affected by soil and vegetation.

Data sources: 

data_Jornada_288001_npp_geomet_bsne_dust_collection

LTER Core Area(s): 

Dataset: 

Study number: 

262

Data set ID: 

210262004

Abstract: 

   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.
 

Data sources: 

data_Jornada_262004_ecotone_npp_by_form

LTER Core Area(s): 

Dataset: 

Study number: 

262

Data set ID: 

210262010

Abstract: 

   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.

   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.

   Variables measured:  Rodent abundance expressed as Minimum Number Known Alive (MNKA),
                        rodent biomas, rodent energy, and rodent species richness.

Data sources: 

data_Jornada_262010_ecotone_rodent_metrics_1st_capture

LTER Core Area(s): 

Keywords: 

Dataset: 

Study number: 

262

Data set ID: 

210262008

Abstract: 

   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.

Data sources: 

data_Jornada_262008_ecotone_rodent_1st_capture

LTER Core Area(s): 

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