The effects of fire on nitrogen cycling processes within Bandelier National Monument, NM
Contribution to Book
Fire effects in southwestern forests: proceedings of the second La Mesa fire symposium
General Technical Report Rocky Mountain Forest and Range Experiment Station, USDA Forest Service
Nitrogen is often the nutrient limiting production in conifer for- ests. Fire acts as a mineralizing agent, releasing nutrients in available forms. However, nitrogen is lost during fires, which can further deplete this limiting nutrient. Without fire, nitrogen becomes tied up in partially decom- posed litter (needles and woody debris). The problems faced by manag- ers of these forest systems are how and when to use fire from a nutrient perspective. A chronosequence of fire intervals in ponderosa pine forests (Pinus ponderosa) was studied to determine (1) if nitrogen cycling pro- cesses (mineralization and nitrification) decrease and (2) if concentrations of organics that inhibit these processes increase along the fire chronosequence. Patterns were not statistically significant, but fairly clear trends occurred. Nitrogen mineralization and nitrification patterns were higher in sites recentry burned (within two years) and were lowest in sites without fire since the 1890's. The patterns at intermediate age sites var- ied, perhaps because of differential usage by elk and variable amounts of needle scorch which resulted in differential needle litterfall after fire. Within a site, concentrations of certain monoterpenes were consistently nega- tively correlated with rates of nitrification and mineralization. In these sys- tems, fire promotes more rapid cycling of nitrogen, in part through com- bustion of monoterpene inhibitors.
White, C.S., "The effects of fire on nitrogen cycling processes within Bandelier National Monument, NM" (1996). Aspen Bibliography. Paper 1615.