Disturbance

LTER Core Area: Disturbance

Aggregate mesquite litter mass following soil-litter mixing and decomposition in a semi-arid grassland from 2010-2012

Study number: 

301

Data set ID: 

210301002

Date range: 

2010-04-01 to 2012-10-31

Original investigator: 

Dan Hewins

Data contact: 

Abstract: 

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

 

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.  

 

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 download: 

Aggregate mesquite litter chemistry following soil-litter mixing and decomposition in a semi-arid grassland from 2010-2012

Study number: 

301

Data set ID: 

210301001

Date range: 

2010-04-01 to 2012-10-31

Original investigator: 

Dan Hewins

Data contact: 

Abstract: 

The effect of vegetation structure on soil-litter mixing (SLM) and decomposition was explicitly tested in a litterbag experiment on a Chihuahuan Desert grassland site where vegetation cover was manipulated to simulate the progressive loss of grass cover accompanying livestock grazing and woody plant encroachment.  We hypothesized that (i) reductions in grass cover would destabilize soi

The effect of vegetation structure on soil-litter mixing (SLM) and decomposition was explicitly tested in a litterbag experiment on a Chihuahuan Desert grassland site where vegetation cover was manipulated to simulate the progressive loss of grass cover accompanying livestock grazing and woody plant 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 is of the percent carbon, percent nitrogen, and the carbon to nitrogen ratio.

Data download: 

Stressor II transect line point intercept data

Study number: 

461

Data set ID: 

210461001

Date range: 

1996-02-27 to 2009-10-27

Original investigator: 

Kris Havstad

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 download: 

Conmod Pilot Study: Annual vegetation transect Line Point Intercept measurements

Study number: 

308

Data set ID: 

210308002

Date range: 

2008-06-10 to 2009-07-27

Original investigator: 

Debra Peters

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
    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 download: 

Conmod Pilot Study: Annual plant canopy gap and basal gap intercept data

Study number: 

308

Data set ID: 

210308001

Date range: 

2006-06-10 to 2009-07-11

Original investigator: 

Debra Peters

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

Precipitation Measured at Four Locations in the Tromble Watershed from 6/2010 to 10/2011

Study number: 

338

Data set ID: 

210338002

Date range: 

2010-06-06 to 2011-09-30

Original investigator: 

Ryan Templeton

Abstract: 

Precipitation at 1 minute intervals for rain gauges 2-5 with R1 excluded due to periods of interruption.  Spatially averaged rainfall over the watershed is calculated in this dataset based on relative coverage of each rain gauge determined from a Theissen polygon map.

Precipitation at 1 minute intervals for rain gauges 2-5 with R1 excluded due to periods of interruption.  Spatially averaged rainfall over the watershed is calculated in this dataset based on relative coverage of each rain gauge determined from a Theissen polygon map.

Data download: 

Abrasion of crust at Scrape Site

Study number: 

122

Data set ID: 

210122001

Date range: 

1995-09-01 to 2011-12-31

Original investigator: 

Dale A Gillette

Abstract: 

Distance of crust surface to a crossbar set into the soil. Three "torvane" measurements that measure the torque needed to break the crust is also recorded. These measurements are made monthly near each of three monitoring towers (East, Middle, West) on the Scrape Site.

Distance of crust surface to a crossbar set into the soil. Three "torvane" measurements that measure the torque needed to break the crust is also recorded. These measurements are made monthly near each of three monitoring towers (East, Middle, West) on the Scrape Site.

Data download: 

East and west boundary fence plant line intercepts - percent cover for all species beginning 1986

Study number: 

120

Data set ID: 

210120001

Date range: 

1986-09-24 to 2005-10-29

Original investigator: 

Walter G Whitford

Data contact: 

Abstract: 

BACKGROUND. In the spring of 1982, as part of the establishment of the Jornada Long-Term Ecological Research site in southern New Mexico, a 135 ha portion of a 1500 ha, internally drained, watershed was exclosed from grazing by domestic livestock. Prior to exclosure the watershed, as well as the rest of the Jornada basin, had been moderately to heavily grazed for the past 100 years.

Concurrent with grazing, the vegetation had undergone a dramatic change from desert grassland, with an almost continuous cover of C4 perennial grasses, to isolated patches of the original grassland in a mosaic with desert shrub dominated plant communities (Buffington and Herbel, 1965). The exclosure lies along a northeast facing piedmont slope at the base of a steep isolated mountain peak, and covers a variety of component landforms from the foot of the mountain to the basin floor. This provided the opportunity to investigate the response of vegetation with respect to landscape characteristics as well as release from grazing. This summary data set consists of percent cover of all perennial plant species from the plant line intercept measurements on either side of the LTER-I exclosure East and West boundary fence. Data is sorted by treatment (grazed, ungrazed), year, fence line, station, then species i.d. Along the East Boundary fence line, the east side is ungrazed (control) and the west side is grazed (treatment). Along the West Boundary fence line, the east side is grazed and the west side is ungrazed. Each plant line transect is divided into 6 5-meter segments. All perennials were measured at about 5 year intervals as the length of intercept for each species along a 30-meter line oriented perpendicular to the fence. Summary data presented in this data set is the average percent cover for the outer-most 2 5-meter segments for the respective treatment (grazed or ungrazed). The term outer-most is relative to the fence. The 5-meter segment on either side of the fence is not included in the cover estimates due to fence line effect disturbances; e.g., cattle trails, tumbleweeds trapped along fence, etc. This summary data does not include the first year of measurement in 1982 because of numerous problems with species codes used that could not resolved.

Data download: 

East and west boundary fence plant line intercepts - percent cover for 9 species, Jornada Basin, 1982 to 1992

Study number: 

120

Data set ID: 

210120002

Date range: 

1982-10-08 to 1992-09-11

Original investigator: 

Walter G Whitford

Data contact: 

Abstract: 

BACKGROUND. In the spring of 1982, as part of the establishment of the Jornada Long-Term Ecological Research site in southern New Mexico, a 135 ha portion of a 1500 ha, internally drained, watershed was exclosed from grazing by domestic livestock. Prior to exclosure the watershed, as well as the rest of the Jornada basin, had been moderately to heavily grazed for the past 100 years.

Concurrent with grazing, the vegetation had undergone a dramatic change from desert grassland, with an almost continuous cover of C4 perennial grasses, to isolated patches of the original grassland in a mosaic with desert shrub dominated plant communities (Buffington and Herbel, 1965). The exclosure lies along a northeast facing piedmont slope at the base of a steep isolated mountain peak, and covers a variety of component landforms from the foot of the mountain to the basin floor. This provided the opportunity to investigate the response of vegetation with respect to landscape characteristics as well as release from grazing. This summary data set consists of percent cover of 9 species from the plant line intercept measurements on either side of the LTER-I exclosure East and West boundary fence. Data is sorted by station, species i.d., then line segment. Along the East Boundary fence, the east side is ungrazed (control) and the west side is grazed (treatment). Along the West Boundary fence, the east side is grazed and the west side is ungrazed. Each plant line transect is divided into 6 5-meter segments. All perennials were measured at about 5 year intervals as the length of intercept along a 30-meter line perpendicular to the fence. Summary data includes only four of the 6 5-meter intervals due to disturbance along fenceline. Data from the 5-meter segment on either side of the fence was not included in summarizing the data. Summary data includes only 9 of the perennial species.

Data download: 

Estimated daily precipitation at the 15 ANPP sites: 1980-2010

Study number: 

425

Data set ID: 

210425001

Date range: 

1980-01-01 to 2010-12-31

Original investigator: 

Jin Yao

Data contact: 

Abstract: 

Estimated daily precipitation is calculated for each of 15 aboveground net primary productivity (ANPP) sites located in the 5 dominant vegetation zones on the Jornada Basin. The 15 sites were formally established in 1989 as LTER Study 268, but these rainfall estimates begin in 1980 using the closest rain gauge that provides a minimum resolution of daily precipitation data.

The Methodology section describes this in detail. The rain gauges are detailed inthe file raingauge_picks.csv.

Data download: 

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