Ecosystem Analysis of the Tallgrass Prairie: Nitrogen Cycle

Abstract

Nitrogen cycling in tallgrass prairie was studied by using nitrogen content and concentration data for various ecosystem components on grazed and ungrazed tallgrass prairie in northeast Oklahoma. The seasonal dynamics of N in various plant parts was described, and the annual flow of N among different compartments was calculated. A simulation model was used to study the effect of grazing, fertilization, irrigation, and fire on nitrogen cycling. The results show that grazing, fertilization, and irrigation increase the nitrogen cycling rates. Annual spring fires reduce plant uptake and mineralization of N from plant parts, while mineralization of N from organic matter is increased.

Responses of herbage and cattle tail switch hair δ15N value to long-term stocking rates on a rough fescue grassland

“…Lower NDF and ADF concentrations in herbage collected from grazed N value in NDF and ADF fractions in the grazing treatment than the ungrazed Control reflect enhanced N uptake as soil nutrient availability increases through accelerated organic N mineralization and release of readily available N forms under grazing (Risser and Parton 1982). In addition, accelerated N cycling (Risser and Parton 1982) under grazing also caused preferentially lighter N ( 15 N values in herbage in these two grazed treatments (in GSC reported by Li et al 2009, and in NDF and ADF reported in Tables 2 and 3). Additionally, the strong correlations between the two (Fig.…”

Nutrient redistribution by grazing cattle drives patterns of topsoil N and P stocks in a low-input pasture ecosystem

“…Nitrogen (N) and phosphorus (P) are the mostcommonly growth-limiting nutrients in grassland ecosystems (Clark 1977;Risser and Parton 1982) and important determinants of patterns in species composition and richness (Ellenberg 1996;Marini et al 2007). Large herbivores, such as cattle, play a dominant role in the cycling of N and P in pastures (Floate 1981;Williams and Haynes 1990;Haynes and Williams 1993;Rotz et al 2005).…”

Journal of Range Management, Volume 56, Number 3 (May 2003)

“…Soil microbial biomass C in the top 12 cm of soil ranged from 277 to 581 mg CO2 -C kg' in the burned treatment and from 170 to 569 mg CO2 -C kg' in the unburned treatment. This response was a result of the higher temperatures reached by the soil during burning (Garcia 1992), which increased plant residue decomposition rates and the mineralization rates of organic matter (Risser and Parton 1982).…”