19. Arizona Fescue Ecological Series Table 19-1. Full and short names for the ecological types in the Arizona Fescue Ecological Series. Ecological Type Plant Association Code Name Code Short Name Arizona fescue/pingue–Moderately deep to shallow residual Arizona fescue/pingue– GA02 Argiborolls, gravelly surface–Linear to convex exposed FEAR2/PIRI6 Shallow–Windward slopes shoulders and summits, 8,400–9,600 ft Arizona fescue/muhly–Shallow to deep colluvial Argiborolls, FEAR2/MUMO- Arizona fescue/muhly– GA03 sometimes Lithic, gravelly surface–Linear to convex somewhat MUFI Deep–Windward slopes protected slopes, 8,700-10,500 ft This is the Festuca arizonica series of Once Arizona fescue is eliminated from a site, Komárková (1986) and of Moir (1983), who management can do little to reestablish it, and considers it a non-climatic series. It includes the must instead manage the remaining less-palatable Fescue series, in part, of Donart and others (1978) species, such as pingue, needle-and-thread, and and Dick-Peddie (1993), and the Danthonia parryi junegrass, which reach peak growth in the spring. series, in part, of Hess (1981) and Komárková Loss of Arizona fescue considerably reduces the (1986). It includes the Muhlenbergia montana value of the forage on a site, especially in summer series, the Picradenia richardsonii series, and the and fall for cattle, and in winter for elk. Artemisia frigida series of Komárková (1986). Evaporation is typically great from these sites, Stands of this series occupy small- to medium- and water percolates quickly through the soil. sized sites, which are usually easy to distinguish Arizona fescue and muhly counteract these forces. from sagebrush or other shrublands on aerial These plants and their litter on the soil surface hold photos, though they are sometimes confused with much moisture and retain it through the growing black sagebrush sites. In the UGB, these sites season. occupy gravelly soils, often in rainshadow climates Total aboveground vegetation production in (Ramaley 1942). They occur on well-drained these sites can be as high as 1,700 lb/ac/yr when benches or in well-drained parks, usually above the the site is in good to excellent condition (Aldon and lower tree line. Klemmedson (1983) discusses Barstad 1987). mineral and nutrient cycles. Vegetation/Climate/Soils Table 19-2. Climate and Soils Arizona fescue (Festuca arizonica) is an Characteristic Value Reference obligate outcrosser, so pollen must be transferred 510 mm/yr (420-600 mm/yr) from one plant to another to set seed. The Precipitation zone 20 in/yr Weaver 1979 maximum distance between plants for successful (16-24 in/yr) pollination is 2-3 m (6-9 ft). Arizona fescue roots Mean annual 8°C (-3°C to 18°C) are shallow but densely matted, holding tightly to air temperature 46°F (26°F to 64°F) the upper few centimeters of soil, preventing erosion, and over time increasing its organic Fire Management content. Sites are often windy, and the wind nearly always blows from the same direction, creating a Prescribed burning can increase long-term hostile environment for soil formation. production of forage grasses, and typically increases their nutrient content and digestibility Once Arizona fescue plants are more than 3-4 m (Clary 1978). But these sites are usually too sparse (9-12 ft) apart, usually through grazing by livestock to carry a fire, except possibly in conjunction with or big game, stands regress (Dayton and others adjacent sagebrush sites. 1937). Existing fescue plants senesce and die without reproducing. When the fescue root mats Range and Wildlife Management die, the organic-rich upper soil layer is free to Early researchers were aware of the erode, being removed through the action of wind or vulnerability of Arizona fescue to damage from water from spring snowmelt. Eroded sites are grazing. Dayton and others (1937) noted that it is effectively set back to primary succession; 1,000 “not particularly resistant to grazing and even years or more may be required for Arizona fescue moderately close grazing tends to reduce the cover to reestablish, probably during a favorable period … the greatest [range] damage usually occurs in the of several decades with higher than normal dry period of late spring and early summer before a moisture and less wind. vigorous, lush growth of the grass has been made. This damage is accentuated on poorly watered and 456 heavily stocked range. … Care should be taken that the ranges are not overstocked, especially in the dry 8 late spring and early summer period, and that uniform distribution is secured.” Herzman and 7 others (1967) observed that “Moderate to heavy 6 grazing reduces the stand of Arizona fescue,” while 5 Judd (1962) noted that Arizona fescue “disappears quickly under close grazing and is thus a sensitive 4 indicator of proper grazing management.” 3 Leaf height, in Sites supporting the same Arizona fescue 2 grassland type as is found in the UGB are an 1 important component of a low-elevation bighorn sheep winter range (but not the intermediate range 0 JE 1 JY 1 SE 1 AG 1 JE 10 JE 20 JY 10 JY 20 AG 10 AG 20 or summer-lambing range) west of Saguache near MY 10 MY 20 the UGB. Within bighorn winter range, Arizona Seasonal date fescue (FEAR2), blue grama (CHGR15), fringed sage (ARFR4) and mountain muhly (MUMO) are major Light Moderate Heavy components of bighorn diets (Shepherd 1975). Figure 19-2. Growth in height of mountain muhly (MUMO) leaves in a ponderosa pine stand in east-central Colorado in three pastures with different cattle-use intensities (Johnson 1953) 14 Recreation, Roads & Trails, Scenery 12 Ridgetop or shoulder sites are unsuitable for 10 developed or dispersed recreation because of 8 shallow soils and high winds. More-protected sites are moderately suitable for recreational activities 6 that do not disturb the soil, though they are Leaf Height, in 4 probably less suitable for developed recreation. These sites are suitable for roads and trails, but 2 roadbeds should be kept on or close to the surface, 0 as cut banks do not hold very well in the gravelly JE 1 JY 1 SE 1 AG 1 soils. Sites on ridges are not suitable for JE 10 JE 20 JY 10 JY 20 AG 10 AG 20 MY 10 MY 20 Seasonal Date construction because of high winds. Revegetation and Rehabilitation Light Moderate Heavy Arizona fescue is resistant to drought and trampling (Dayton and others 1937), but it Figure 19-1. Growth in height of Arizona fescue (FEAR2) leaves in produces few viable seeds even in dense stands, a ponderosa pine stand in east-central Colorado in three pastures with different cattle-use intensities (Johnson 1953). and even fewer germinate and survive (Dayton and others 1937), which presents problems for revegetation and for commercial seed growers. Arizona fescue is a prime candidate for local harvesting of seed for revegetation, but sites must be protected after seeding, a daunting task. Any revegetation effort is severely limited by the fact that erosion of the organic-rich topsoil (2-3 in deep) usually follows disturbance or any other decline of the fescue population. Needle-and- thread is one of the few native grasses that will grow in the subsoil of these sites. 457 45 4.5 40 4 35 3.5 30 3 m c 25 2.5 n, o i m at t i c , p i h t c e w 20 2 r o P Gr y hl 15 1.5 ont M 10 1 5 0.5 0 0 AP-1 AP-15 MY-1 MY-15 JE-1 JE-15 JY-1 JY-15 AG-1 AG-15 SE-1 SE-15 OC-1 OC-15 NO-1 NO-15 DE-1 DE-15 JA-1 JA-15 Seasonal Date FEAR2-leaf FEAR2-culm MUMO-leaf MUMO-culm Precipitation Fig. 19-3. Growth of Arizona fescue (FEAR2) and mountain muhly (MUMO) in ponderosa pine stands in northern Arizona (Pearson 1967). Notice that Arizona fescue apparently needs June and July drought to initiate culm growth. Key to Ecological Types in the Arizona Fescue Series 1. Mountain muhly (MUMO), slimstem muhly (MUFI), or Parry oatgrass (DAPA2) present, and the sum of cover of these three species >10%; usually one or more of these three is conspicuous, >25% cover .......................GA03 1. Mountain muhly and Parry oatgrass both absent; sometimes slimstem muhly present but always <5% cover... ......................................................................................................................................................................GA02 Table 19-3. Characteristics of Ecological Types within Ecological Series 19 in the Upper Gunnison Basin. Numbers are shown in form Average (Minimum-Maximum) Cover, %: Trees Total Live Avg. Aspect, Surface: Shrubs Cover, % Code °M (r) Soil Depth, cm Coarse, % Graminoids No. Species Short Name No. Samples Elevation, ft Slope, % Coarse, % Mollic, cm Bare, % Forbs TLC/NS, % GA02 0 (0-0) 71.4 (43.7-140.9) Arizona fescue/pingue– 9,041 268 (0.86) 64 (26-162) 58 (24-77) 9 (0-21) 19 69 (36-87) 30 (22-39) Shallow–Windward (8,420-9,520) 20 (6-34) 20 (7-40) 7 (1-19) 42 (18-73) 2.4 (1.4-4.1) slopes 20 (5-67) GA03 0 (0-0) 88.1 (29.4-167.0) Arizona fescue/muhly– 9,669 166 (0.54) 54 (20-95) 30 (5-71) 7 (0-41) 20 54 (14-79) 27 (17-38) Deep–Windward (8,760-10,480) 25 (6-111) 22 (0-52) 31 (1-90) 59 (15-117) 3.4 (1.1-5.6) slopes 22 (3-54) 458 GA02 ARIZONA FESCUE/PINGUE–SHALLOW–WINDWARD SLOPES FEAR2/PIRI6 Arizona fescue/pingue–Moderately deep to shallow residual Argiborolls, gravelly surface– Linear to convex exposed shoulders and summits, 8,400–9,600 ft Wind Figure 19-4.