|Data by Research Category|
Dataset: NPP Study: Annual aboveground net primary production, summary by site
Summarizes mean aboveground net primary production, in g/m2/yr, by year for each of 15 sites. Annual totals derived by summing seasonal production values for winter (October - February), spring (February - May), and fall (May - October) increments for a single calendar year.
Please refer to these publications to evaluate the appropriateness of these data for your intended use prior to contacting Debra Peters, Responsible Investigator, with a data request.
- Peters, Debra P. C., Jin Yao, Osvaldo E. Sala, and John P. Anderson. 2012. Directional climate change and potential reversal of desertification in arid and semiarid ecosystems. Global Change Biology 18, no. 1 151-63. doi 10.1111/j.1365-2486.2011.02498.x.
- Peters, Debra P. C., Jin Yao, Dawn Browning, and Albert Rango. 2014. Mechanisms of grass response in grasslands and shrublands during dry or wet periods. Oecologia 174 1323-34.
Attention: These data are not appropriate for estimates of percentage cover. NPP-associated percent cover measurements were developed for and are used solely to provide the best estimate of biomass production. Becuase the methodology results in measurements of overlapping subcanopy systems and canopies of adjacent individuals, NPP percent cover measurements are not an appropriate measure of actual aerial plant cover. Doing so will result in inflated numbers for the "actual" vegetative cover.
Attention: Data through 2003 was replaced online per below on 9/22/2011. Analyses and results for ANPP differ from previous uses of the data from 1989-1998 (Huenneke et al., 2002) in three ways: (1) Yucca elata was removed prior to analysis because its growth form results in large errors in biomass estimates from year-to-year, (2) regressions between biomass and plant volume used an intercept equal to 0 to be consistent with a recent study in a similar system (Muldavin et al., 2008), and (3) reference harvests obtained in extreme years resulted in adjusted regression coefficents through time that reflect year-to-year variation in ANPP. These changes result in ANPP values that are smaller compared (Peters et al. submitted) with previous studies (Huenneke et al., 2002).
Fifteen sites (3 in each of 5 ecosystem types) were selected for monitoring of NPP. Sites, abbreviations, and location summarized here and on LTER site map; directions are from stone pillars / gate marking entrance to Jornada Experimental Range, 6.6 mi north of US Hwy 70, east of Las Cruces, on North Jornada Road: Creosote - Caliche C-CALI From stone pillars, go 4.1 mi north to South Well. Turn left, drive 3.4 mi to College Ranch HQ. Turn left, drive south 1.3 mi (going through gate and crossing LTER transects); turn right (this is 2nd right) and proceed 0.3 mi. Turn left on small track; site is on right (uphill) of road, 70 m from turn. Creosote - Gravel C-GRAV From stone pillars, go 4.1 mi north to South Well. Turn left, drive 3.4 mi to College Ranch HQ. Turn left, drive south 3.4 mi (going through gate and crossing LTER transects, passing Upper Trailer). Site is on left (E) of road. OR - from stone pillars, turn left and proceed 2.6 mi; turn right at gate and go 0.6 mi along power line road, then 0.4 mi along right fork. Site is on right (E) of road. Creosote - Sand C-SAND From stone pillars, go 4.1 mi north to South Well. Turn left, drive 3.4 mi to College Ranch HQ. Turn left, drive south 1.6 mi (going through gate and crossing LTER transects). Site is on left (E) of road. Grassland - Basin G-BASN From stone pillars, go 4.1 mi north to South Well. Turn left, drive about 1 mi; park in pull-off on left adjacent to fence. Enter fence through gate; site is uphill about 50 m. Grassland - IBP G-IBPE From stone pillars, go 4.1 mi north to South Well. Take 2nd left (i.e., AFTER the well) and drive 8 mi (this is SW boundary of Exp. Range). IBP exclosure is on left of road 0.2 mi after it turns north away from boundary. OR - from stone pillars, go 10.2 mi north to JER HQ; past shop area, turn left and go 6.4 mi to West Well. Turn left (S) and go 1.4 mi to exclosure. Grassland - Summerford G-SUMM From stone pillars, go 4.1 mi north to South Well. Turn left, drive 3.4 mi to College Ranch HQ. Turn left, drive south 1. mi (going through gate and crossing LTER transects). Turn right (this is 1st right), drive 0.5 mi to power line road, turn left. Site is 0.3 mi from turn, uphill from power line at base of rocks. Mesquite - North M-NORT From stone pillars, go 10.2 mi north to JER HQ; past shop area, turn left and go 2.4 mi to junction with pipe line road, turn right. Proceed 0.6 mi N. Park; site is located about 400 m to west inside fenced exclosure. Mesquite - Rabbit M-RABB From stone pillars, go 10.2 mi north to JER HQ; past shop area, turn left and go 3.4 mi to Rabbit Rain Gauge parking area. Site is to north (left) of road, about 75 m, inside fenced exclosure. Mesquite - West M-WELL From stone pillars, go 10.2 mi north to JER HQ; past shop area, turn left and go 6.4 mi to West Well. Stay on road straight past well; site is about 150 m west of well, on right of road. OR - from IBP grassland exclosure, drive 1.4 mi north, turn left at West Well, site is about 150 m from well. Playa - College P-COLL From stone pillars, go 4.1 mi north to South Well. Turn left, drive about 2.5 mi to Lower Trailer (on left); park there and continue on foot along road to stiles over fence on right. Concrete block paths lead to playa. NPP grid is in western portion of fenced area of playa, just east of College Ranch HQ and pasture. Playa - Small P-SMAL From stone pillars, go 4.1 mi north to South Well. Turn left, drive about 3.4 mi to College Ranch HQ. Proceed through gate and HQ area; road jogs north and then heads west again. Proceed 3.8 mi from HQ; take small road on left, downslope 0.4 mi (through gate) to playa. Playa - Tobosa Tank P-TOBO From stone pillars, drive 10.2 mi north to JER HQ. Jog to right past shop, continue north 3.1 mi. Site is to right of road in fenced portion of large depression. Tarbush - East T-EAST From stone pillars, drive 2.6 mi north. Site is on right of road (E), in fenced area. Tarbush - Taylor T-TAYL From stone pillars, go 4.1 mi north. Turn right just before South Well. Take jog to left (N) across cattle guard, proceed east 2.3 mi. Site is on right (S) of road about 20 m in fenced area. Tarbush - West T-WEST From stone pillars, go 2.4 mi north. Site is on left (W) of road, in fenced area. Each site is a grid of 49 quadrats, each 1 m x 1 m, located 10 m from one another in a 7 x 7 square (quadrats make up a 60 m x 60 m square with 10 m buffer zones around boundary). Exception is P-COLL, where limited space forced us to use a 3 x 16 arrangement (48 quadrats).
field data sheetsMethods:
Field sampling described in project documentation. Analysis of aboveground biomass by species described in documentation for plant biomass datasets (NQBIOxxy DAT). Productivity for an interval estimated as described in documentation for project; that is, all positive increments in biomass for a species in a quadrat for an interval are summed to total productivity for that square meter. Estimated mean productivity summed for 3 increments in a calendar year (xx winter, xx spring, and xx summer) to yield estimated annual production, October - October.
Three times per year, February, May, and October
DWREG.SAS used to produce regressions from harvest data; NQBIOxxy.SAS used to produce biomass by species by quadrat for a given sample date; PROD.SAS used to calculate productivity for individual quadrats from two successive NQBIOxxy.DAT files, and to summarize by calculating averages per site.