Journal of Range Management, Volume 37, Number 1 (January 1984)
http://hdl.handle.net/10150/635596
2024-03-29T01:59:59ZJournal of Range Management, Volume 37, Number 1 (January 1984)
http://hdl.handle.net/10150/650484
Journal of Range Management, Volume 37, Number 1 (January 1984)
Complete digitized issue.
1984-01-01T00:00:00ZWater Balance Calculations and Net Production of Perennial Vegetation in the Northern Mojave Desert
http://hdl.handle.net/10150/645740
Water Balance Calculations and Net Production of Perennial Vegetation in the Northern Mojave Desert
Lane, L. J.; Romney, E. M.; Hakonson, T. E.
Measurements obtained between 1968 and 1976 indicate the influence of climatic factors and soil characteristics upon soil moisture and production of perennial vegetation in the northern Mojave Desert. Seasonal distribution patterns of precipitation are shown to have a strong effect on plant-available soil moisture, and these patterns are, in turn, reflected in net production of perennial vegetation. Available climatic data and soil characteristics were used as input to a continuous simulation model to calculate the water balance for a unit area watershed. Computed and measured soil moisture agreed quite well over a range of values from close to the wilting point to near field capacity. We used computed evapotranspiration rates to estimate water use by perennial vegetation. Computed water use was multiplied by a water use efficiency factor to estimate net production of perennial vegetation. Estimated net production exhibited year-to-year variability comparable with measured values, and agreed quite closely with available observations. This paper briefly describes soil-water-plant relationships in the northern Mojave Desert and illustrates an application of a continuous simulation model to predict soil moisture and net production of perennial vegetation. Based on our analysis, the simulation model would appear to have potential for estimating the water balance and above ground net primary production on arid and semiarid rangelands.
1984-01-01T00:00:00ZVegetation and Litter Changes of a Nebraska Sandhills Prairie Protected from Grazing
http://hdl.handle.net/10150/645735
Vegetation and Litter Changes of a Nebraska Sandhills Prairie Protected from Grazing
Potvin, M. A.; Harrison, A. T.
End of season components of biomass and litter were measured on a Nebraska Sandhills prairie site to follow vegetation changes during the first 4 years following the cessation of intense livestock grazing. The 1977-1980 mean annual end of season biomass at Arapaho Prairie, a Sandhills prairie site, was 109 g/m2. Summer grazing on Arapaho Prairie was terminated in 1977, and as a result, significant increases in the biomass of the deep-rooted, palatable warm-season (C4) grasses, sand bluestem, little bluestem and switchgrass, have occurred since then. The biomass of the shallowly rooted C4 grama grasses for the 4-year period was significantly correlated with growing season precipitation. Significant decreases in end of season biomass of the cool-season (C3) grasses during the same 4-year period were highly correlated with yearly decreases in May precipitation. Following the removal of grazing, litter increased from 40 to 127 g/m2 from 1977 to 1980. A nonsignificant yearly increase in litter production occurred in the third year after grazing as a steady state of litter production and decomposition was approached.
1984-01-01T00:00:00ZUsing Weather Records with a Forge Production Model to Forecast Range Forage Production
http://hdl.handle.net/10150/645733
Using Weather Records with a Forge Production Model to Forecast Range Forage Production
Wight, J. R.; Hanson, C. L.; Whitmer, D.
This paper describes a method for calculating site specific forecast yields and their associated probabilities of occurrence. A physically based range forage model, which utilizes beginning soil water content and daily precipitation, mean air temperature, and solar radiation as inputs, calculates the ratio of actual transpiration (T) to potential transpiration (Tp) as a yield index. Annual yield is calculated by the relationship: yield = potential site yield (yield when water is nonlimiting) × T/Tp. By using the current year's beginning soil water content and weather data for a number of years, a population of yields is generated (one yield for each year of weather data). From the population of yields, a mean and various confidence intervals around the mean can be calculated as the forcast yield and its associated confidence intervals. The forecast procedure was tested using 55 years (1917-1971) of weather records and 12 years (1967-1978) of actual yield and soil water data for an upland range site in eastern Montana. An expected two thirds of the field measured yields were within a standard deviation of the forecasted yields for the April, May, and June forecasts.
1984-01-01T00:00:00Z