Herbicide Conversion of a Sand Shinnery Oak (Quercus Havardii) Community: Effects on Nitrogen

Abstract

Seasonal nitrogen dynamics were documented in an undisturbed sand shinnery oak (Quercus havardii) community and in similar areas treated with tebuthiuron 3 years and 6 years prior to sampling in 1981. Percent nitrogen was determined for above- and below-ground biomass compartments and for the soil by depth using semimicro Kjeldahl analyses. Total nitrogen by weight in the ecosystem showed no change from the untreated rangeland to the 3-year-old treatment but was 14% higher on the 6-year-old treatment than on the control. Less nitrogen occurred in oak biomass compartments on the treated plots than on the control and more nitrogen occurred in the herbaceous compartments on the treated plots than on the control. Nitrogen (%) was similar for all compartments on the untreated and 3-year treatments but was slightly higher for all compartments on the 6-year-old treatment than on the other 2 sites. Soil nitrogen was slightly higher (3%) on the 3-year-old treatment than on the control and was 16% greater on the 6-year-old treatment than on the untreated rangeland.