Great Basin Naturalist


Gambel oak (Quercus gambelii Nutt.) is increasingly recognized as a valuable fuelwood throughout Arizona, Colorado, New Mexico, and Utah. Knowledge of distribution of nutrients among biotic and abiotic components is an important step in developing prescriptions for managing these stands for sustainable productivity.

Eight Q. gambelii stands were sampled for concentrations (%) and accumulations (kg ha−1) of total nitrogen (N), phosphorus (P), sulfur (S), calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) among aboveground and belowground biomass components and the upper 30 cm of soil. Highest concentrations of N, P, and S occurred in oak leaves, understory leaves, and the forest floor layer. Generally, highest concentrations of Ca, Mg, K, and Na occurred in the soil.

The greatest proportion of the total capital of individual nutrients was contained in the soil (82%–99%). Aboveground components of live biomass, standing and down-dead, and forest floor contained 10%, 14%, and 8%, respectively, of total capitals of N, P, and S. The forest floor had the largest accumulation (63%) of total nutrients (N, P, S, Ca, Mg, K, and Na) of live and dead aboveground components. Nutrient accumulation in live biomass was heavily weighted to the belowground component. The dense system of roots, rhizomes, and lignotubers comprising 56% of total biomass contained 62% of the total accumulation of nutrients in live biomass.

Low levels of total P in the soil and accumulation of 14% of the ecosystem total of P in aboveground biomass components suggest the need for a better understanding of the role of P in productivity of these stands in development of prescriptions for management of residues after harvest.