Response of Wavyleaf Oak to Nitrogen Fertilization

Abstract

This study was conducted to determine the response of wavyleaf oak to nitrogen fertilization, at rates of 0, 112, and 224 kg of elemental nitrogen per ha. Over the three years of the study, twigs were longer on fertilized areas than on unfertilized areas. Nitrogen at 112 kg/ha was generally as effective as 224 kg/ha in stimulating twig growth. Slope position did not have an effect on all sites. Where slope position was significant, plants on the upper and middle slopes responded better to fertilization than did plants growing on lower slopes. Site appeared to influence twig growth more than slope. Differences in twig growth among sites were attributed to differences in soil depth and density of vegetation. Twig length was significantly different among years due to uneven distribution of rainfall. As wildlife populations are restricted to less favorable areas, it is increasingly important to develop new and better methods of habitat manipulation. One important area involves improvement of quality and quantity of food, as demonstrated in several studies of mule deer (Odocoileus hemionus) and white-tail deer (0. virginianus). Deer densities can be controlled by quantity and nutritive quality of available forage (Hagen 1953, Swank 1956). Many deer diseases are due to inadequate nutrition (Lang 1957, Taylor and Hahn 1947), and fertility levels in deer generally correspond with the quality of their range (Cheatum and Severinghaus 1950, Julander et al. 1961). Recently, fertilization has gained importance in improvement of wildlife ranges. Williams (1969) stated that soil fertilization may be valuable in correcting nutritional deficiencies occurring within a wild population, providing the deficiencies are properly diagnosed and fertilizers are administered accordingly. Fertilization can significantly increase production of range plants (Schultz et al. 1958) and substantially increase carrying capacity of the range (Ward and Bowersox 1970). Fertilization can cause major compositional changes in vegetation (Basile 1970, Gibbens and Pieper 1962, Schultz et al. 1958), improve the palatability of certain species (Brown and Mandery 1962, Gibbens and Pieper 1962, Schultz et al. 1958), and improve the quality of forage (Rogler and Lorenz 1957, Ward and Bowersox 1970, Wood 1966). On the Fort Stanton Cooperative Experimental Range, Anderson et al. (1974) fertilized mountain mahogany (Cercocarpus montanus) and wavyleaf oak (Quercus undulata) with urea at the rate of 101 kg nitrogen (N)/ha. The mounAuthors are professor, Department of Fishery and Wildlife Sciences, New Mexico State University, Las Cruces 88003; research scientist USDA, Rangelands Weed and Brush Control, Tucson, Arizona 85719; and professor, Department of Experimental Statistics New Mexico State University, Las Cruces, New Mexico 88003. This study was supported by the New Mexico Agricultural Experiment Station and McIntire-Stennis funds. Nipak, Inc., Dallas, Texas donated the fertilizer for this project. This Journal Article 681, Agricultural Experiment Station, New Mexico State University, Las Cruces, New Mexico 88003. Manuscript received August 7, 1978. tain mahogany showed a growth response to the fertilizer, and the percent crude protein in leaves of wavyleaf oak increased. Mule deer use was greater on fertilized plots than on control plots. Since oak constitutes a major portion of mule deer diets in the Southwest (Anderson et al. 1965, Boeker et al. 1972, Lamb 1971, Smith 1959), this study was initiated to determine growth response of wavyleaf oak to different rates of fertilization in a pinyon-juniper woodland.