Data set ID:
The purpose of this investigation was to answer three general questions: 1. How does the modification of soil properties and the ratios of resources (e.g., water-N) by ants alter species assemblages of winter annual plants at the edge of the ant nests? 2. How does the "spring cleaning", clipping, predation or herbivory by ants affect success of the winter annual plants at the edge of ant nests? 3. Are there significant differences in the floristic assemblage and belowground standing crop (root biomass) between the edge of ant nest and the surrounding unaffected soils? Data set contains chemical analyses for soil samples collected from five ant nests for each of the three sites for total nitrogen, (ammonium, nitrate), inorganic phosphorus, and exchangeable cations (K+, Na+, Ca2+ and Mg2+). Also included is below ground biomass from five ant nests for each of the three sites.
field data sheets
On 24 June 1987, soil samples were collected from five ant nests for each of the three sites for analysis of total nitrogen, (ammonium, nitrite, nitrate), inorganic phosphorus, and exchangeable cations (K+, Na+, Ca2+ and Mg2+). The two quadrats of the ant nest edges were randomly sampled once with a 400-cm3 core (20 cm depth) and the soil samples were mixed together. The same procedures were used for the two quadrats of adjacent reference sites.
All chemical analyses were determined on the < 2-mm soil fraction. Total nitrogen was measured by microKjeldahl digestion (Bremmer & Mulvaney, 1982) and analyzed twice. Ammonium (NH4-N), nitrite (NO3-N), and nitrate (NO3-N) were extracted with 100 ml of 2 N KCl on 10-g soil samples and were measured as described by Keeney and Nelson (1982). Inorganic phosphorus (P) was extracted with 100 ml of 0.5 M NaHCO3 on approximately 10-g soil samples and was measured on an autoanalyzer. Exchangeable cations (K+, Na+, Ca2+ and Mg2+) were extracted with 1 N ammonium acetate (pH 7.0) and were analyzed with an atomic absorption spectrophotometer. On 24 June 1987, below ground biomass was measured at only five ant nests from each of the three sites. A 400 cm3 soil core sample was taken from each quadrat (edges and reference). Roots were cleaned with a 2-mm sieve, oven-dried for 72 hours at 60 C and carefully weighed.
This study was conducted at three sites on the Jornada LTER during winter-spring 1987. A burrograss-tobosa swale grassland was site 1, an area dominated by the perennial grasses Scleropogon brevifolia (burrograss) and Hilaria mutica (tobosa). This area is located 3,000 ft. (1,000 m) SE of the playa bottom or playa basin (College Playa) and subject to rare sheet flooding. A playa fringe (College Playa) was site 2, an area characterized by scattered Prosopis glandulosa (mesquite) mixed with Yucca elata and Larrea tridentata (creosotebush). The upper basin slope was site 3, an area characterized by a fairly uniform cover of Xanthocephalum sarothrae (snakeweed) and a high diversity of annual forbs and grasses. The soil series described on the watershed by Wierenga et al. (1987) from site 1 to site 3 are Dalby (Typic Torrerts, fine), Headquarter (Ustollic Haplargid, fine loamy), Bucklebar (Typic Haplargid, fine-loamy), and Dona Ana (Typic Haplargid, coarse-loamy), respectively.