LTER Core Area: Organic Matter
Leaf weight-per-unit area of Larrea tridentata from creosote zone on LTER-I Control and Treatment transects was calculated. Litter used was collected from 4 litter baskets placed under each of 10 bushes on Control Transect and also the Treatment transect. Litter was from month of October litterfall. Thirty whole leaves were picked from each bush, dry weight obtained, soaked in H20 to soften, flattened, and run through area meter.
Mesquite litterfall collected monthly from mesquite fringe on south side of College Playa. Oven-dry weights of leave, stem, and seed fractions as well as total dry weight are recorded.
Creosotebush litterfall collected monthly from creosotebush zone Creosotebush litterfall collected monthly from creosotebush zone on upper bajada between College Playa and Mt. Summerford. Oven-dry weights of leave, stem, and seed fractions as well as total dry weight are recorded.
Rabbit pellets were collected from 24 5x5m plots at approximately 1 month intervals. Dry weight by date and plot was recorded. Plots are located along LTER-1 Control and Treatment transects in creosotebush (around station C62 and T61) and upper basin slope
Rabbit browse (clippings) were collected from 24 5x5m plots at approximately 1 month intervals. Dry weight by date and plot was recorded. Plant material collected was subsampled and analyzed for Total N. Plots are located along LTER-I Control and Treatment transects in creosotebush (around station C62 and T61) and upper basin slope (around station C48 and T46). (See site description.)
Rabbit browsed (=clipped) plant material found lying on the ground was collected from 24 5x5m plots at approximately 1 month intervals. Dry weight by species, date and plot was recorded. Material was subsampled and analyzed for Total N. Plots are located along LTER-1 Control and Treatment transects in creosotebush (around station C62 and T61) and upper basin slope. See site description.
Termites are important to litter decomposition and nutrient cycling in desert grasslands. The annual feeding activity on paper baits of subterranean termites in desertified (degraded-shrub dominated ecosystems) and relatively undegraded black-grama (Bouteloua eriopoda) grasslands was measured over six years on 12 sites on the Jornada Basin. Toilet paper roll termite baits were placed on grids on each consumer plot. Data include initial bait weights and bait weights after baits had been retrieved from the field once each year. Weight loss was calculated as a measure of termite foraging activity. This study is complete.
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 % organic matter of soils sampled in January 1987 from ant nests and adjacent reference sites.
Overview: In semiarid ecosystems the diversity of plant functional types ( grasses, shrubs, succulents, and so on) and of species may interact with the severe stresses imposed by the desert environment to influence ecosystem processes. Erosion and transport of surface sediment by wind and water is one process that may be affected by the physical structure of the plant community. The Jornada plant diversity experiment, in which the diversity and structure of the plant community have been manipulated in large (25 m x 25 m) plots, offers the opportunity to examine the relative importance of vegetation characteristics and landscape position in determining rates of sediment movement within the plots. Each of the 48 plots of the plant diversity experiment contains 5 pans or trays on the downslope side; these accumulate sediments and plant litter that are moving within the plots (carried by wind or by water). Data have been collected on the amount of sediment accumulated in the pans during rainy and during dry seasons, with material sorted and weighed as fine (< 2 mm diameter) or coarse > 2 mm) mineral sediment, plant litter, or rabbit/jackrabbit pellets. Previous statistical analyses found that the mass of material collected per plot is explained only poorly by the treatment (plant community manipulation) of the plot and by block (a rough indication of location on the slope). Objectives: We will test the relative significance of the following variables in explaining plot-level accumulations of sediment and litter: treatment, block, position on slope (the row, from 1 (top of slope) to 10 (bottom), in which the plot is located), the treatment of the plot immediately upslope from the plot, and indices of plant cover and volume (total and by functional group) from the plot-level sampling of vegetation (using fall 1997 data). In addition, we will test the significance of the following variables in explaining the accumulation of sediment and litter in individual pans within a plot: all variables listed above for the plot, plus indices of the vegetative cover and volume located immediately upslope of the pan (weighted for distance from the pan itself). Response variables: Vegetative cover measurements are made immediately upslope of erosion pans to estimate plant cover and volume. This is done at two scales. The three large quadrats (2 m x 2 m) are used to look at all large plants (height > 25 cm) rooted within them. The six small plots (50 cm x 50 cm) are used to look at all small plants (greater or equal to 3 cm maximum diameter, but less than or equal to 10 cm) rooted within them. Maximum diameter, maximum perpendicular diameter, and height are measured to the nearest centimeter.