LTAR

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

Dataset: 

Study number: 

308

Data set ID: 

210308003

Abstract: 

    Material moved from the overland flow of water resulting from precipitation is collected in
    belowground containers to get an estimate of that material entering and exiting the plots.
    Water and material collected in a container solely from a rain or wind event is not collected.
    Bedload oven-dry weight is obtained and the percent Loss on Ignition is calculated.

Data sources: 

data_Jornada_308003_conmod_pilot_bedload

LTER Core Area(s): 

Dataset: 

Study number: 

407

Data set ID: 

210407001

Abstract: 

    This data set is comprised of daily precipitation totals, in inches, measured by Belfort
     Instruments weighing rain gauges at 58 locations on the Jornada Experimental Range.
     Locations and the dates during which data were collected at them were generally project-oriented.
     See comment section (#20) for start and end dates for each location.

    Days on which data could not be obtained (due to equipment failure, user error, and/or
     other reasons) are flagged as missing within this dataset.  As of 31 December 2008 they
     comprised 1,270 of the total 291,465 records, which is less than 0.44% of the data set.
 

Data sources: 

data_Jornada_407_jer_recording_raingauge_network

LTER Core Area(s): 

Keywords: 

Dataset: 

Data set ID: 

DSL2005039

Abstract: 

Soil samples were collected from mesquite dune site, and analyzed for nutrients.

LTER Core Area(s): 

Dataset: 

Data set ID: 

DSL2005027

Abstract: 

This data set consists of soil analyses for nitrate,
ammonium, total nitrogen, moisture content, organic matter, mite
weight, nematode weight and root weight of Erioneuron pulchellum
soil rhizosphere samples taken at monthly intervals from Silva\'s
dissertation research plots. Twenty 6 x 6 m plots were established
with a 3 m buffer between plots. Five plots were randomly
assigned to one of four treatments: (1) chlordane amendment
100ml AI (active ingredients) per 10,000 ml) to exclude
microarthropods, (2) sprinkler irrigation (6 mm per week),
(3) sprinkler irrigation (6 mm/week) plus chlordate amendment (as
above), (4) control (no treatment). Three randomly located
subsamples were taken from each plot.

Dataset: 

Study number: 

301

Data set ID: 

210301002

Abstract: 

Mesquite litter mass loss from decomposition associated with soil-litter mixing.

 

Decomposition models typically under-predict decomposition relative to observed rates in drylands. This discrepancy indicates a significant gap in our mechanistic understanding of carbon and nutrient cycling in these systems. Recent research suggests that certain drivers of decomposition that are often not explicitly incorporated into models (e.g., photodegradation and soil-litter mixing; SLM) may be important in drylands, and their exclusion may, in part, be responsible for model under-predictions. To assess the role of SLM, litterbags were deployed in the Chihuahuan Desert and interrelationships between vegetation structure, SLM, and rates of decomposition were quantified. Vegetation structure was manipulated to simulate losses of grass cover from livestock grazing and shrub encroachment. I hypothesized that reductions in grass cover would promote SLM and accelerate mass loss by improving conditions for microbial decomposition.  This study is complete.

 

For more see: Hewins, D. B., S. R. Archer, G. S. Okin, R. L. McCulley, and H. L. Throop. 2013. Soil-litter mixing accelerates decomposition in a Chihuahuan Desert grassland. Ecosystems 16:183-195

Data sources: 

data_Jornada_301002_aggregate_littermass

LTER Core Area(s): 

Dataset: 

Study number: 

301

Data set ID: 

210301001

Abstract: 

Decomposition models typically under-predict decomposition relative to observed rates in drylands. This discrepancy indicates a significant gap in our mechanistic understanding of carbon and nutrient cycling in these systems. Recent research suggests that certain drivers of decomposition that are often not explicitly incorporated into models (e.g., photodegradation and soil-litter mixing; SLM) may be important in drylands, and their exclusion may, in part, be responsible for model under-predictions. To assess the role of SLM, litterbags were deployed in the Chihuahuan Desert and interrelationships between vegetation structure, SLM, and rates of decomposition were quantified. Vegetation structure was manipulated to simulate losses of grass cover from livestock grazing and shrub encroachment.

We hypothesized that (i) reductions in grass cover would destabilize soils and promote SLM, and (ii) that SLM would enhance microbial abundance and alter microbial community composition in ways that accelerate decomposition. To test our hypotheses, we quantified mass loss, and chemistry of litter incubated on sites with experimental reductions in grass cover (0 to 100% removals) over a 12-month period.  This dataset includes data pertaining to the percent carbon, percent nitrogen, and the carbon to nitrogen ratio. This study is complete.

Data sources: 

data_Jornada_301001_aggregate_litterchem

LTER Core Area(s): 

Dataset: 

Study number: 

461

Data set ID: 

210461001

Abstract: 

The goal of this sampling effort is to describe the vegetation response to treatments.  Data were collected following the line-point intercept method (Herrick et al. 2009).  Although the original LPI data set was in multivariate form with separate columns for canopy layers and soil surface, this data set has been transposed into vertical form, implementing a “layer” variable, so that all species and soil surface codes appear in one column.  Within each exclosure, 4837 points were sampled with the following exceptions:

year

exclosure

total_points_sampled

1996

5

4825

1996

7

4836

1996

9

4836

1996

10

4836

1997

1

4830

1997

2

4830

1997

3

4830

1997

4

4830

1997

5

4830

1997

6

4830

1997

7

4830

1997

8

4830

1997

9

4830

1997

10

4830

1997

11

4830

1997

12

4830

1997

13

4830

1997

14

4830

1997

15

4830

1997

16

4830

1997

17

4830

1997

18

4830

2002

12

4835

 

Data sources: 

data_Jornada_461001_stressor_ii_plant_line

LTER Core Area(s): 

Dataset: 

Study number: 

228

Data set ID: 

210228001

Abstract: 

Dataset consists of horizontal dust flux at multiple heights from BSNE dust collectors located in treatment plots (different percent vegetation removed) and adjacent downwind effect plots. Year 2008 was an annual collection. Collection in subsequent years occurred before and after the wind season. The experiment was designed to test the effects of increasing wind erosion on soil and vegetation properties at the Jornada.  In order to increase wind erosion rates, vegetation was removed to increase bare surface area and stimulate erosion (the less vegetation present the greater the wind erosion).  The basic experimental design includes three treatment blocks.  Each block has four treatment plots with different level of vegetation removed (25-100%) and a control treatment.  Treatment plots are 25x50m with 25m buffers between.  The vegetation removal includes grasses and small shrubs (like XASA and ZIGR), but not mesquite or yucca or any of the larger shrubs).  Also, adjacent downwind plots are included in the design.  These plots are strictly for monitoring of soil and vegetation properties, so no maintenance is required on these areas.

Data sources: 

data_Jornada_228001_neat_bsne

LTER Core Area(s): 

Keywords: 

Dataset: 

Study number: 

308

Data set ID: 

210308002

Abstract: 

    Line-Point Intercept data are collected annually for this project beginning in 2008. No data were
    collected in 2011. There are 4 pairs of plots consisting of control and treatment. Each plot is
    8x8 meters with an 8x8 meter buffer plot above and below it. Treatment plots have connectivity modules
    (conmods) installed to decrease gap size between perennials.  Buffer plots do not have conmods.
    Four 24-meter transects run through the plot and 2 buffer plots. These transects are spaced
    0.8, 2.8, 4.3, and 7.2 meters across the plots (denoted as 1, 3, 5, and 7 meters in the database),
    paralleling the long axis of the combined buffer plots and central plot.
         Aeolian site:         Control plots 2,4,5,8  Treatment plots 1,3,6,7
         Dona Ana site:        Control plots 2,4,5,7  Treatment plots 1,3,6,8
         Gravelly Ridges site: Control plots 1,3,5,7  Treatment plots 2,4,6,8
 

Data sources: 

data_Jornada_308001_conmod_pilot_plant_line

LTER Core Area(s): 

Keywords: 

Dataset: 

Study number: 

308

Data set ID: 

210308001

Abstract: 

Canopy Gap and Basal Gap Intercept data are collected annually for this project beginning in 2008. No data were collected in 2011. There are 4 pairs of plots consisting of control and treatment. Each plot is 8x8 meters with an 8x8 meter buffer plot above and below it. Treatment plots have connectivity modules (conmods) installed to decrease gap size between perennials. Buffer plots do not have conmods. Four 24-meter transects run through the plot and 2 buffer plots. These transects are spaced 0.8, 2.8, 4.3, and 7.2 meters across the plots (denoted as 1, 3, 5, and 7 meters in the database), paralleling the long axis of the combined buffer plots and central plot.
Aeolian site:                Control plots 2,4,5,8  Treatment plots 1,3,6,7
Dona Ana site:            Control plots 2,4,5,7  Treatment plots 1,3,6,8
Gravelly Ridges site:  Control plots 1,3,5,7  Treatment plots 2,4,6,8

Data sources: 

data_Jornada_308001_conmod_pilot_gap

LTER Core Area(s): 

Keywords: 

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