Data set status is completed, indicating that data is no longer being collected
Atmospheric deposition as found in dryfall (dust) and wetfall precipitation has been collected and analyzed since 1983 using an Aerochem Metrics wetfall/dryfall collector located at the Jornada LTER weather station north of Las Cruces, NM, USA. Wetfall occurring as precipitation is collected after each event with a sample size large enough to analyze. Each sample is analyzed for Br, Ca, Cl, F, HPO4, K, Mg, Na, NH4, NO3/NO2, SO4, Total N, and Total P. Analysis of Sr and Dissolved Organic Nitrogen was discontinued in 2003. Dryfall data are available as a separate data package.
t: The goal of this Master’s thesis project, which was carried out in July and August of 2016, was to assess the effect of inferred grazing intensity on 1) vegetation cover type and 2) soil organic carbon (SOC) at the Jornada Experimental Range in southern New Mexico. A sampling transect was established at each of 3 long term cattle water sources (85-106 years old), beginning 5m from the water source and continuing 1500m outward. Soil bulk density, soil organic carbon, soil organic nitrogen, and dominant plant cover type (shrub, grass, and bare soil) were sampled at 20 locations on each transect. Two hypotheses evaluated in this study are: 1) higher grazing pressure near the water source will lead to reduced vegetation cover and C inputs into the soil, leading to higher SOC stocks in soil with far proximity to the water source; and 2) Grazing very close to the water source will exert high disturbance and deposit SOC via defecation, leading to higher SOC stocks in soil with close proximity to the water source.
A figure of the data in this package: https://jornada.nmsu.edu/sites/jornada.nmsu.edu/files/files/data/Cattle_soil_carbon_figure.jpg
Location on EDI: https://portal.edirepository.org/nis/metadataviewer?packageid=knb-lter-jrn.210472001.1
This completed dataset, collected in 2001, contains soil particle size analysis (PSA) and sand fractionation data from soil cores collected at 116 quadrat locations that are part of the Jornada Experimental Range's long-term Permanent Quadrats study. The goal of this effort was to help characterize plant-scale factors related to vegetation dynamics observed in the Permanent Quadrats. At each quadrat location, 4 cores were collected at 2 depths (0-5cm and 5-20cm) and assessed for percent sand, silt and clay. The sand fraction, if large enough, was then separated into 5 sand size classes (53-106 micrometers, 106-250 micrometers, 250-500 micrometers, 500-1000 micrometers, 1000-2000 micrometers) to measure the percent fraction of each.
Composition of Sand Fraction at 116 Permanent Quadrats: https://jornada.nmsu.edu/sites/jornada.nmsu.edu/files/files/data/Quadrats_Sand_Fractionation_0.jpg
Soil Particle Size Analysis at 116 Permanent Quadrats: https://jornada.nmsu.edu/sites/jornada.nmsu.edu/files/files/data/Quadrats_PSA_0.jpg
Repeat digital groundbased photos are taken once to twice a year to document plant litter and
soil deposition or removal by wind and water transport on ten microplots located on each of the
8 plots at each of the Aeolian, Dona Ana, and Gravelly Ridges sites. Five photos are taken of
each microplot: One overhead (from directly over the microplot) and 4 lateral views at ground
level of the microplot from each cardinal direction.
Digital filenames are fully descriptive of the site, plot, microplot, photo view, and date taken.
Photo filename structure:
Where 1 = site: A=Aeolian: D=Dona Ana; G=Gravelly Ridges
2 = plot (1-8)
3 = microplot (1-10)
4= photo view (O=overview; E=looking east; N=looking north; S=looking south; W=looking west
5-6-7 = year month day of photo
8 = original image number assigned by camera
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.
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
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.
A 2-year experiment with ambient, reduced, and enhanced precipitation was designed to compare the performance of the encroaching C3 shrub (honey mesquite Prosopis glandulosa) to the dominant C4 grass (black grama Bouteloua eriopoda) in terms of photosynthetic rates and leaf water status. Precipitation manipulations dramatically enhanced natural variability and generated a range of rainfall scenarios that could have only been studied only after a multi-decade effort using natural conditions. Responses were highly asymmetric, with precipitation (PPT) additions generally influencing volumetric water content (vwc) to a greater extent than PPT reductions. Desert soils are usually close to their minimum water content and thus when soils were dry, the effects of reducing PPT were relatively minor compared to the effects of adding PPT. Volumetric soil water content was, on average, lower and more variable at the shallower (0–5 cm) depth (mean 9.3 ± 0.14%; range 5.7–14.3%) than at the deeper (30–50 cm) depth (mean 14.4 ± 0.12%; range 10.8–18.1%. This study is complete. For further information and results, see:
Throop, H., L. G. Reichmann, Os. Sala, and S. Archer. 2012. Response of dominant grass and shrub species to water manipulation: an ecophysical basis for shrub invasion in a Chihuahuan desert grassland. Oecologia 169: 373-383.
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.
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.