Plant root biomass data where grazing height/frequency were simulated by mowing

The Mowing Experiment Biophysical Measurements data set was collected to quantify the effects of grazing and nitrogen fertilization on primary productivity and plant chemistry. The data in this data set quantified the effects of foliage removal on plant net primary productivity (NPP), plant nutrient content and the effects of grazing pressure as simulated by mowing. Mean values and their variances are reported. Standing crop values reflect treatment effects of removing biomass periodically, but the productivity levels show the inverse effects, suggesting plant compensatory growth mechanisms. Grazing intensity was defined as the amount of leaf area remaining following defoliation. The latter was manipulated experimentally by mowing at several heights. Grazing frequency was defined as the number of times foliage removal occurred in each year and included grazing and mowing history as well as current mowing frequency.

This data set records the productivity of a semiarid shortgrass prairie steppe located in the Central Plains Experimental Reserve (CPER)/Pawnee National Grassland in north-central Colorado. There are nine data files (.txt). Four files contain measurements of monthly dynamics of harvested above-ground plant biomass, one file each for untreated, irrigated, fertilized, and irrigated + fertilized plots for the period 1970 to 1975. The fifth file contains annual above-ground NPP estimates for the untreated plot for the period 1970-1974. The sixth file contains long-term ANPP estimated from field harvest measurements made between 1970 and 1990 and by correlation with forage production measurements made between 1939 and 1990. Two additional files provide estimates of above- and below-ground NPP based on peak growing season harvests; one record covers 1970-1972 from the Pawnee site and the other covers 1985-1988 from CPER. The ninth file contains climate data for 1912-1990 from a weather station located at CPER.Revision Notes: This data set has been revised to correct the study site elevation, extend the temporal coverage, and add four data files containing estimates of NPP. Please see the Data Set Revisions section of this document for detailed information.

Estimates of plant standing crop, plant productions & consumption by herbivores

Light radiation striking a vegetative canopy interacts with individual phyto-elements (i.e., leaves, stems, branches) and the underlying substrate. The interaction depends on light quality, radiative form (direct or diffuse), illumination incidence angle, vegetative component optical properties and canopy architecture. Radiation is reflected, transmitted or absorbed. Mowing, grazing, and fertilization can affect the canopy architecture or optical properties of vegetation, thus changing the canopy reflectance. This study examined the response of spectral reflectance characteristics (using an Exotech radiometer) to canopies that were manipulated using simulated grazing and fertilization of plots. The spectral reflectance data set supports the original hypothesis of a curvilinear relationship between productivity and grazing intensity. Reflectances for the four MSS bands and the standard error for each are reported. These data were collected at two locations within the northwest quadrant of the FIFE study area during the growing season of 1987. Reflected radiation measurements were converted to radiances and reflectance factor. The reflectance factor is the ratio of the target reflected radiant flux to an ideal radiant flux reflected by an ideal Lambertian standard surface irradiated in exactly the same way as the target.

The Biophysical Properties of the Vegetation Data Set were collected as part of the larger FIFE Science effort to characterize the physical and biological properties of the sites within the FIFE study area over the life of the field experiment. These data were collected at 43 locations scattered throughout the FIFE study area between May 1987 and August 1989. The measurements of leaf area were based on an optical technique in which the area of the light beam obscured by the material under the beam is a measure of the surface area of that material relative to the total surface area that the beam covers. The resulting Leaf Area Indices (LAI) provide a relative measure of leaf area. These indices, when compared between plant samples provide an indirect and relative measure of plant biomass.