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A project funded by the Joint Fire Science Program

The study area is located within a single watershed on the northern rim of the Grand Canyon in the western Colorado plateau. The administrative boundaries of the project are within the National Park Service portion of the Grand Canyon–Parashant National Monument, an area jointly managed with the Bureau of Land Management, Arizona Strip Field Office. The site is at 6,200 feet, with slopes from 2-15%. Mean annual precipitation is 33 to 43 centimeters, bimodally distributed in summer monsoons from late June to early September, and winter frontal systems from November through March. Mean annual soil temperature is 27 to 31 degrees C, and the frost-free period is 135 to 150 days.

The Natural Resource Conservation Service conducted an Order Three-Soil Survey for the site in 1999, which indicated the soils are a well-drained, gravelly loam (35-55% clay) with a neutral pH 7.2 from the surface (A1 0 to 1 inch) and a neutral pH of 6.6 from 1 to 6 inches below the surface. The soil parent material is limestone with depth to bedrock ranging from 19 to 60 inches. Chert gravel covers 50 to 70% of the soil surface. The potential plant community composition includes an understory of >50% native perennial grasses, although current perennial grass cover is much lower.

Based on pre-treatment brush belt transects installed in 2002 by the NPS-FMH crew, we are able to describe the current plant community at the study site. Dominant woody perennials include Utah juniper (Juniperus osteosperma) (1,864/ha), singleleaf pine (Pinus monophylla) (1,792/ha) big sagebrush (Artemesia tridentata var. tridentata) (1,337/ha), antelope bush (Purshia mexicana var. stansburyana) (1,204/ha), broom snakeweed (Guterrezia satrothrae) (432/ha), Palmer's oak (Quercus turbinella) (392/ha), and Colorado pinyon pine (Pinus edulis) (200/ha). Dominance of herbaceous species was difficult to determine because sampling was done after a few drought years, but species that were observed included in descending order of relative cover were sulfur flower (Eriogonum umbellatum), red brome (Bromus rubens), squirreltail (Elymus elymoides ssp. elymoides), cheatgrass (Bromus tectorum), and blue grama (Bouteloua gracilis).

European settlement of the site occurred in the mid 1800’s including extensive cattle grazing throughout the area until the late 1980’s when grazing was ceased on the site and a cattle exclosure fenceline was constructed along the boundary line with the Bureau of Land Management just to the north of the project area. Historic evidence of prolific cattle grazing remains in the study region including corrals, drift fences and earthen water tanks. Some of this region was chained in the late 1950’s to early 1960’s by a local rancher to try and improve range forage conditions. The area was “withdrawn land” by the Bureau of Reclamation in the 1930’s and was transferred to the National Park Service in 1964.

Fire suppression has likely occurred concomitantly with European settlement and organized fire fighting responsibilities have been shared by the BLM and NPS since the 1950’s. A Prescribed Natural Fire Plan was implemented for the area in 1998 and fires are currently being managed has “wildland fire for resource benefits” which is synonomous for allowing naturally caused fires to burn under certain management prescribed conditions.

Lightning storms commonly occur in the area throughout the monsoon season. There is historical evidence of moderate size fires up to 100 acres in area, but in the last 25 years smaller fires less than 1 acre and single tree fires were more common. The NPS has implemented over 6,000 acres of prescribed fires in the area since the program started in1994. Prescribed burn objectives were only met on approximately 1,500 of those acres, which included the majority of the old-chained areas. Most of the untreated/unchained areas did not carry fire with the use of a helitorch under extreme fire weather conditions. Monitoring has shown that plant diversity has generally increased in burned areas, however native grasses have only increased in small isolated areas, possibly due to a previously depleted soil seedbank. The need for alternative treatments besides simply re-introducing fire is necessary to meet resource objectives.

Current management goals at this site are to preserve, restore, and maintain naturally functioning ecosystems and cultural resources. Other goals are to maximize native plant and animal diversity within the natural range of variation. Primary management concerns are related to soil preservation and it is believed that current site conditions will not adequately sustain soil resources. The site is ideal to conduct restoration activities since cattle grazing has been excluded, no elk exist in the area, and deer, small mammals and insects are the only remaining grazers. The lack of excessive grazing pressure should facilitate the re-establishment of native grasses and forbs. The Lake Mead Exotic Plant Management Team is available to control invasive plants in the event the treatment sites become sources of exotic plant invasion in the area.