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Wildlife, Animals, and Plants
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FIRE EFFECTS
SPECIES: Hesperostipa comata
| Needle-And-Thread Grass
Needle-and-thread grass is top-killed by fire. It may be killed if the aboveground stems are completely consumed [22]. Needle-and-thread grass in sagebrush ecosystems is classified as slightly damaged by fire [106,110,111,], and in Intermountain rangelands, as severely damaged [139].
Wright and Klemmedson [137] performed burning studies on needle-and-thread grass plants in Idaho. Burning in June killed more than 90% of needle-and-thread grass plants, while only 20% burned in July died, and none burned in August died. Needle-and-thread grass' dense culms, with a lot of dead material, will continue to burn after the fire has burned over the stand; resulting temperatures can be lethal to underground parts[134,136,137,139]. Charring down into the growing points is noticeable in needle-and-thread grass plants following burning [134]. Large plants are more susceptible to fire kill than smaller plants [139].
Some studies indicate that needle-and-thread grass becomes more resistant to burning from spring through summer as tissues dry out and root storage of carbohydrates increases [1,95,134]. However, this finding contradicts Wright [133], who claimed mortality of needle-and-thread following burning peaks in July and August and declines slightly in September.
Wright [133] claims that the large amounts of dead material in needle-and-thread grass culms cause the plant to burn completely regardless of weather or fire conditions, and that complete defoliation can itself result in mortality, regardless of heat effects in the base of the culm [134].
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Needle-and-thread sprouts from the caudex following fire [1,46]. Recovery generally takes 2 to 10 years [138,139].
Post-fire productivity and coverage usually decrease for 1 season and then increase in the following year, although this response is not consistent. In Wind Cave National Park, South Dakota, needle-and-thread grass coverage decreased for the 1st season following a spring prescribed burn and then rapidly increased in the following 2 seasons [56]. Following a prescribed burn and a wildfire elsewhere in the southern Black Hills, South Dakota, needle-and-thread grass production was significantly higher (p<0.05) on the burned than on unburned control plots in the 1st year following the fire [20]. Following an August wildfire in eastern Idaho in a curlleaf mountain mahogany (Cercocarpus ledifolius)/bluebunch wheatgrass type, needle-and-thread grass frequency and coverage percentage slightly increased in the 1st year over an unburned control [30]. In North Dakota, 2 years following a prairie fire, needle-and-thread grass cover increased by 100% [90].
In contrast, in the Nebraska Sandhills, a lightning strike started a fire in October in a sand bluestem (Andropogon gerardii var. paucipilus)-little bluestem (Schizachyrium scoparium)-prairie sandreed (Calamovilfa longifolia)-needle-and-thread grass-blue grama (Bouteloua gracilis)-hairy grama (B. hirsuta)-spike dropseed (Sporobolus cryptandrus) grassland. In the following year, needle-and-thread grass biomass on unburned sites was not significantly different from biomass on burned sites in June, July, and August, but by October, biomass on unburned sites was higher (p<0.05) [98].
Fire did not affect the root biomass of needle-and-thread grass following a late-summer fire in a northern Nevada grassland [95].
Blank and Young [18] studied the effects of heating the substrate and exposing seeds to burned soil and big sagebrush smoke on needle-and-thread grass seedling emergence, and plant growth response to aqueous extracts of heated soil and smoke. Emergence rate and maximum emergence of seedlings of needle-and-thread grass were significantly (p<0.05) greater in heated substrates than controls. However, exposure to sagebrush smoke significantly reduced the rate of and maximum emergence of needle-and-thread grass. When seeds were pretreated with smoke, needle-and-thread grass had significantly greater leaf elongation rates for the first 30 days of growth. Number of leaves, rate of leaf formation, and above- and belowground biomass were also higher following smoke treatment. Soaking in the soil solution resulted in significantly less aboveground biomass than the control. The authors did not identify the agent in sagebrush smoke that resulted in these growth effects.
In Wind Cave National Park, a spring (April 21) prescribed burn in 1976 in a mixed grass prairie association resulted in significantly greater (p<0.10) yield of needle-and-thread grass over the unburned control in the 1st year following the fire, and significantly less (p<0.10) yield in the 2nd year [114]. The authors explained these differences by the 2nd year having lower precipitation, and an observed stimulation of flowering, in both inflorescence numbers and size, in the 1st year after burning.
In contrast, in Idaho, the number of inflorescences per needle-and-thread grass plant decreased following fire [41]. In North Dakota, in the 1st year following a spring burn, no needle-and-thread grass inflorescences were found [49].
In Wind Cave National Park, needle-and-thread grass decreased in frequency following 2 spring burns. The author postulated that the mild preceding winters caused the grass to green up earlier than usual, and therefore, it was at an advanced phenological point and more susceptible to fire damage than it usually would be in April [118].
On an upland mixed-grass prairie site in Badlands National Park, South Dakota, burning needle-and-thread grass in April and October both reduced aboveground biomass (p<0.05) for up to 3 growing seasons. The authors concluded that the greater damage occurred in April because the plants were actively growing, unlike October, and that needle-and-thread grass is intolerant to both spring and fall burning [131].
Following a lightning-caused fire in the Nebraska sandhills, needle-and-thread grass coverage increased 12% on burned hilltops but decreased 16% on north and south-facing slopes [23].
A big sagebrush-steppe community type that burned naturally in late summer was studied to determine the effects of cheatgrass competition on the recovery and growth of needle-and-thread grass. Needle-and-thread grass plants had significantly less (p<0.05) biomass in the study plots in which they competed with cheatgrass than in those in which they did not. The authors concluded that cheatgrass depletes the soil water quickly and takes advantage of soil spaces left by plants killed by the fire. Cheatgrass uses the water before needle-and-thread grass [96].
Fall is generally the least harmful season for burning needle-and-thread grass in terms of survival percentage. However, mortality in needle-and-thread grass appears to be related to the amount of dead material in the plant culm, and mortality may occur regardless of the season of the burn or burn conditions. Heavy grazing prior to a burn may reduce dead material and improve survivorship of needle-and-thread grass [134].
Related categories for
SPECIES: Hesperostipa comata
| Needle-And-Thread Grass
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