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Wildlife, Animals, and Plants
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FIRE EFFECTS
SPECIES: Bouteloua hirsuta
| Hairy Grama
Studies on direct effects of fire on hairy grama are lacking. Fire probably top-kills hairy grama.
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Most studies conclude that hairy grama is undamaged by fire, following a season or 2 of decreased production. Production of hairy grama was reduced for 1 or 2 growing seasons following prescribed fires during August, September, and October in south-central Oklahoma, but the authors concluded there was no long-term negative effect on hairy grama [21]. In the Nebraska sandhills, phytomass of hairy grama was significantly less (P<0.05) at the end of the growing season on sites burned the previous year than on unburned sites [49]. Bock and Bock [10] studied the effects of spring and fall prescribed burns in ponderosa pine communities in the southern Black Hills, at Wind Cave National Park, South Dakota. After 2 growing seasons, they found no significant difference (P>0.05) in the ground cover of hairy grama between control and burned plots. However, the plants on the control plots were significantly taller for the 2 years following burning.
In another study, Bock and Bock [9] compared short-term plant response to prescribed burning in a semi-desert shrub grassland in Arizona. The site included plains lovegrass, wolftail, threeawn species (Aristida spp.), sprucetop grama (Bouteloua chondrosioides), sideoats grama, shrubby false mallow (Malvastrum bicuspidatum), tansyleaf aster (Machaeranthera tanacetifolia), wait-a-minute bush (Mimosa biuncifera), velvet-pod mimosa (M. dysocarpa) and yerba de pasmo (Baccharis pteronioides). One year following the June burns, density of hairy grama was significantly less (P<.02) on burned than unburned plots. By the 2nd growing season, however, there was no longer a significant difference.
In Arizona, hairy grama was evaluated for 2 seasons following a June wildfire. Fire appeared to have little or no effect on the density of the plant after two seasons, although density was reduced during the first growing season, compared to the control. After 2 seasons, density of hairy grama compared to other perennial grass species was greater than the control [80].
Annual burning appears to be particularly favorable to hairy grama. Annual burning appears to favor growth of warm-season grasses, while a longer mean fire interval favors cool-season grasses [30]. Anderson and others [2] burned 3 sites in Kansas annually for 10 years to evaluate the effects of fire on prairie species. The presence of hairy grama increased by 12-16% in early- and mid-spring burn treatments (from 3% in the control) and by 8% over the control on a late spring burn. Basal area, however, was not significantly different, although late spring burning slightly decreased the basal area of hairy grama. Collins and others [18] compared average cover of several species in response to annual burns, 4-year burns, and no burns. Cover of hairy grama was higher (4.6%) on the annually burned site than on the other 2 (both at 0.2%).
Dokken and Hulbert [20] looked at prairie communities in Kansas that had burned 3 out of 4 years as part of the management plan. They evaluated hairy grama density on plots that were withheld from burning for 1 and 3 years. On shallow soils (20 to 100 cm deep, cherty silt loam or cherty silty clay loam), stem density was significantly less after 3 years without burning, but on deep soils (silty clay loam), there was no significant difference.
Hairy grama appears to be less affected by fall or winter than spring burns. In Kansas, annual burning in November or March increased cover and frequency of hairy grama, while late April burning, 2- and 4-year burns, and not burning all resulted in lower cover and frequency [31]. However, April prescribed burns in Wind Cave National Park, South Dakota, resulted in increased cover of grama species [63]. Worcester [81] found no significant difference, although a slight increase in productivity occurred from pre- to postfire yields of gramas (blue and hairy) on prescribed burns in Wind Cave National Park, 1 year after May and June burns [81].
Three spring burns, on 20 March, 10 April, and 1 May all increased relative percentages of hairy grama under moderate grazing, compared to an unburned site in Kansas. Of the 3 burns, the March burn increased relative cover the most [45].
In redberry juniper (Juniperus pinchotii) rangelands in Texas, hairy grama occurred significantly less in a 4-year-old burn site than in an 8-year-old and an unburned site [46].
Following prescribed burns in the tallgrass Konza Prairie in Kansas, hairy grama was more prevalent (in terms of percentage cover) in the early years following fire and became less important as other species recovered [30].
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Below average winter and spring precipitation can be particularly damaging to hairy grama's ability to recover following fire [63].
Related categories for
SPECIES: Bouteloua hirsuta
| Hairy Grama
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