|Blank, Robert - Bob|
Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 9/12/2006
Publication Date: 2/12/2007
Citation: Blank, R.R., Chambers, J., Roundy, B., Whittaker, A. 2007. Nutrient availability in rangeland soils [abstract]. Society for Range Management. Paper No. 333. Interpretive Summary:
Technical Abstract: Soil nutrient availability is a major factor influencing plant community composition and susceptibility to invasion by exotic plants. We used resin capsules to integrate, over time, soil nutrient availability at sagebrush-grassland elevation transects in the east Tintic range of Utah and in the Shoshone range of Nevada. At each research area, sites were selected to encompass a precipitation-vegetation gradient; 5 in Utah and 4 in Nevada. In the fall of 2001, treatments applied to replicated plots at each site included prescribed burning, herbaceous vegetation removal (total in Utah, one-half and total in Nevada), and controls. Following treatment application, resin capsules were installed in each plot at a depth of 15 cm in shrub interspaces. Nutrient availability was integrated during 4 separate periods (late fall to spring and spring to late fall for 2 years). Relative to controls, complete herbaceous vegetation removal increased resin availability of NO3- (both states) and Ca+2 and Mg+2 (Nevada only), but only during the second sampling period (growing season). Availability of K+ and ortho-P (both states) and NO3- (Nevada only) was greater on prescribed burned plots than the control plots. For Utah, availability of ortho-P, K+, Ca+2, Mg+2 and Fe generally increased with increasing elevation. Nutrient availability did not display strong trends with elevation for Nevada. Availability of Ca+2, Mg+2, K+, and Fe was greatest during late fall to spring integration periods for Nevada. For Utah, nutrient availability was more erratic among sampling periods. Patterns of nutrient availability can be explained by a combination of decreased root uptake in relation to mineralization, differences in soil water content with season and elevation, and nutrient release from vegetation and soil as a consequence of prescribed burning. Our data suggest that removal of herbaceous vegetation and prescribed burning can raise NO3- availability and risk invasion by nitrophilic species such as B. tectorum. Moreover, nutrient availability can be out of phase with most plant growth; plants capable of uptaking these nutrients during cold periods may have a competitive advantage. Resin capsules have utility in integrating the availability of an array of soil nutrients.