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|Data by Research Category|
Dataset: NPP plant tissue chemistry 1989-1990
Plant nutrient distribution beneath and between plant canopies in the Mesquite, Grassland, Playa, Creosotebush, and Tarbush plant communities. The LTER plant biomass plots were harvested during spring, fall, 1989 and winter 1990, in 5 vegetation zones (Mesquite, Grassland, Playa, Creosotebush, Tarbush), 3 sites per zone (site with low, medium, and high biomass, ranked based on fall-89 biomass). Samples were analyzed for total Kjeldahl N, and total phosphorus. Site ranking based on Fall 1989 biomass estimates: ZONE SITES BIOMASS (using FALL-89 rank of plant) M RABB low M NORT medium M WELL high G IBPE low G SUMM medium G BASN high P TABO low P COLL medium P SMAL high C CALI low C GRAV medium C SAND high T WEST low T TAYL medium T EAST high
Location: Northern Chihuahuan Desert 37 kilometers N of Las Cruces, New Mexico on the NMSU College Ranch and the USDA Jornada Exp. Range. Climate: Characterized by an abundance of sunshine, a wide range between day and night temperatures, low relative humidity, an evapotranspiration rate averaging 229 cm per year, and extremely variable precipitation. The average annual precipitation is 230 mm, with 52% occurring during the summer. Droughts are recurrent climatic phenomenon. Vegetation: We are studying 5 vegetation communities that are dominant on the Jornada and are hypothesized to differ in their degree of desertification: 1) remnant black grama (Bouteloua eriopoda) grasslands; 2) playas or low-lying areas with heavy soils ( which are periodically flooded) and dominated by tobosa (Hilaria mutica) and burrograss (Scleropogon brevifolius); 3) tarbush stands (Flourencia cernua); 4) mesquite dunes (Prosopis glandulosa); 5) creosotebush-dominated bajadas (Larrea tridentata). For each community type, three permanent plots representing a range of primary productivity have been established to examine patterns of NPP, soil moisture, plant nutrients as a function of climatic variation
data sheets, electronic spreadsheet (Microsoft Excel 2.2)Methods:
Sampling: Plots were harvested for NPP within 5 zones (Mesquite, Grassland, Playa, Creosotebush, and Tarbush), within 5 zones (Mesquite, Grassland, Playa, Creosotebush, and Tarbush), on 3 sites per zone (sites with low, medium, and high biomass) during Spring 89, Fall 89, and Winter 89 on the Jornada LTER II site approximately 40 km NNE of Las Cruces, NM. Plant samples are harvested adjacent to permanent NPP sites, avoiding plants obviously damaged by livestock or by previous harvests, or otherwise unrepresentative of plants within permanent quadrats. Dead biomass (other than that obviously produced in current growth season) is removed and discarded; living material is dried and weighed. Samples were analyzed for total kjeldahl N, and total phosphorus. Nutrient Analysis: Soil samples were air-dryed in a glasshouse and ground to pass a 2-mm seive. Total N (and TP) was digested by Kjeldahl digestion block techniques (Bremner and Mulvaney, 1982). Digest NH4-N was analysed using an automated salicylate procedure (Technicon Industrial Method No. 329-74W/B).
1 time in Spring and Fall 1989 and Winter 1990