• IMMEDIATE FIRE EFFECT ON PLANT
• DISCUSSION AND QUALIFICATION OF FIRE EFFECT
• PLANT RESPONSE TO FIRE
• DISCUSSION AND QUALIFICATION OF PLANT RESPONSE
• FIRE MANAGEMENT CONSIDERATIONS

IMMEDIATE FIRE EFFECT ON PLANT:

Columbia needlegrass is generally top-killed by fire. In some instances, particularly with severe fires, soil heating caused by combustion of fine leaves at the soil surface further damages the plant. Researchers classify Columbia needlegrass as slightly to moderately damaged by fire [64].

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:

Specific fire effects depend on the season of burn, phenology, plant size, and fire severity. Season of burn is of primary importance in determining the effects of fire on some needlegrasses [63]. The related species, needle-and-thread (Hesperostipa comata), which begins growth in the early spring, is most seriously injured by midsummer fires and less seriously damaged by late spring or fall burns [58]. Columbia needlegrass also begins growth during the early spring and a similar seasonal fire damage pattern is possible though not documented.

The effects of fire on bunch grasses are related to culm density, culm-leaf morphology, and size of the bunch. Densely clustered, leafy culms may burn long after passage of the flaming front [66]. Columbia needlegrass has relatively few culms per clump which may help to minimize the amount of subsurface heat transfer and subsequent damage. Wright and others [64] classify Columbia needlegrass and western needlegrass (Achnatherum occidentale) as slightly susceptible to damage by fire in sagebrush-bunchgrass communities, whereas needle-and-thread and Thurber needlegrass (Achnatherum thurberiana) are likely to be severely damaged by the fire. This difference appears to be related to the different amounts of dead material per unit basal area between species [7].

Large plants of needlegrass species are more susceptible to fire-caused damage than are smaller plants [64]. Basal area reduction has been noted in all size classes of needlegrasses, with large plants being most severely damaged [66]. With needlegrasses in general, plant size becomes an increasingly important determinant of fire damage late in the summer [63].

PLANT RESPONSE TO FIRE:

Columbia needlegrass is slightly to moderately damaged by fire [36] and has a moderate to rapid (2-10 years) postburn "recovery time" [66]. When the plant is only top-killed, regrowth can begin as early as the first post-burn season [67]. Increases in basal diameter [67], height [67], and dry weight production [5,33] have been recorded following burning. Because Columbia needlegrass does not spread by rootstocks and must await production of seeds, the number of individual plants increases slowly after burning [36].

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

The postfire response of Columbia needlegrass varies with season and intensity of burn, size of plants, and proximity to other fuels.

Fall prescribed burning seemed to stimulate seed production in Columbia needlegrass (number of seeds per plant) in a sagebrush (Artemisia spp.) grassland site [35]. Columbia needlegrasses had more inflorescences per plant and more florets per inflorescence contributing to greater seed production on plants in the 2-year-old burn than on adjacent unburned areas [35]. According to Mueggler and Blaisdell [33], an August prescribed burn to control big sagebrush appeared to benefit Columbia needlegrass in southern Idaho. Response following a variety of treatments was as follows:

Air-dry (lbs/acre)    herbage production     3 years after treatment
Untreated Control     August Burn            Sprayed   
51                    123                    138       
		  

FIRE MANAGEMENT CONSIDERATIONS:

Removal of competing sagebrush through prescribed burning may enhance survival of Columbia needlegrass, unless plants are in close proximity to shrubby fuels [67]. Abundant precipitation after fire may significantly aid recovery of Columbia needlegrass [67]. Pechanec [36] suggests waiting 10 days after seeds of perennial grasses are ripe and scattered before burning.

Related categories for SPECIES: Achnatherum nelsonii | Columbia Needlegrass