Data set ID:
[John Anderson added the following from info provided by Justin Van Zee and edited by Michelle Buonopane.] 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. Soil erosion is also an important indicator of relative disturbance effects of the treatment manipulations. 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).
Data are recorded on data sheets, then entered in the computer for analyses and graphing.
Label heavy duty plastic zip-loc bags with the date, plot number, and pan letter (A-E). The southern most pan is Pan A and continuing north to Pan B, Pan C, etc in each plot. Using either stiff index cards or mini dustpans and paintbrushes, scrape the contents of each pan into the corresponding bag. These then go back to the lab for processing. Any pans not flush with the ground should be emptied and then leveled with the ground. Bags are left open in laboratory to air dry. (No oven drying). The contents of each bag are then separated into 4 components using forceps and a 2 mm seive: sediment with a diameter <2mm, sediment >2mm in diameter, plant litter, and rabbit pellets. These are weighed separately and recorded on the data sheet, entered into a spreadsheet, summarized in Excel, and analyzed in SAS. After project completion, pans are emptied as needed in order to maintain pan location in the case further studies are desired. Soils removed are dumped off-site.
From the stone pillars at the south entrance of the Jornada Experimental Range (USDA), follow the road west approximately 4 miles to the first gate on the right (north). Go through this gate approximately one quarter mile, parking spot is on west side of road under power lines. The biodiversity site is on the right (east) side of the road across from the parking spot.
Varies, roughly 3 or 4+ times each year