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.
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.
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.