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

IMMEDIATE FIRE EFFECT ON PLANT:

Blue wildrye mortality following fire has not been widely documented. Indirect evidence indicates that it may be somewhat susceptible to fire. Leege and Godbolt [54] reported reduced frequencies of blue wildrye 1 year after a spring burn in seral brushfields in a grand fir/pachistima (Abies grandis/Pachistima myrsinites) habitat type in north-central Idaho. However, blue wildrye densities showed little change after fire on chaparral sites in California where nonsprouting forms of manzanita (Arctostaphylos spp.) and ceanothus (Ceanothus spp.) comprised most of the prefire overstory vegetation [78].

PLANT RESPONSE TO FIRE:

Blue wildrye is often "an abundant and characteristic species of old burns and cutover areas" [78,90,92], but few studies have dealt specifically with the postfire response of this species. Limited information indicates that blue wildrye depends in part on residual plant survival and subsequent seed regeneration for postfire establishment. Powell [72] reports that that fire creates an excellent seedbed following moderate-severity burns in mixed-conifer forests, and that most postfire regeneration in those forests may be from surviving seedbank propagules.

Tillering can occur from surviving basal buds located on the root crown. Plants in the Great Plains may also regenerate via short rhizomes [35]. Blue wildrye in the Pacific Northwest is rarely rhizomatous [6,33,43].

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

Results of laboratory experiments suggest that blue wildrye seeds may be able to survive ground surface temperatures generated by moderate-intensity fires. Approximately 39% of seeds exposed for 5 minutes to temperatures ranging from 180 to 200 degrees Fahrenheit (82-93 ^oC) germinated, and 17% exposed to temperatures ranging from 200 to 210 degrees Fahrenheit (93-99 ^oC) germinated. This research indicates that on sites where blue wildrye occurs in the prefire community, viable seed may be available for establishment in the 1st postfire growing season [78].

Although blue wildrye was not recorded as a component of the preburn vegetation on seral brush field sites in northern Idaho, it was recorded on sample plots the 4th growing season after burning [54] and in both pre- and postfire quaking aspen stands in Colorado.

Fire creates seedbeds that appear to be conducive to the successful germination and rapid establishment of blue wildrye [16,39,74 86,]. Seedlings develop rapidly on sites where competing vegetation is greatly reduced. In general, cover of blue wildrye increases for the 1st few years following fire [12], but abundance and vigor may decline after 3 or 4 years. On broadcast-seeded burns in the mountain-brush zone of Utah, blue wildrye established readily and gave high yields for 4 postfire years, but then was suppressed by smooth brome (Bromus inermis) [31]. Mean density of blue wildrye in a California chaparral community (nonsprouting manzanita (Arctostaphylos spp.) and ceanothus (Ceanothus spp.) is presented below [78]:

                                Postfire year							  

				prefire  1    2    3    4    5
-------------------------------------------------------    
plants/thousandth acre	0.6      0.8  1.8  2.6  3.9  4.7

FIRE MANAGEMENT CONSIDERATIONS:

Blue wildrye is recommended for seeding mixtures for revegetating burn sites because it exhibits good germination and establishes rapidly [31,78]. To reintroduce blue wildrye and associated grassland species native to California, McClaran [60] recommends site preparation either by tillage or fire, which should be timed in accordance with the emergence of exotic annual seedlings. In McClaran's study, previously unnoticed remnant natives including blue wildrye showed a flush of growth and an increase in seed set in response to burning. However, blue wildrye may be quickly suppressed by other commonly seeded species. On a site in a grand-fir/pachistima habitat type in north-central Idaho, blue wildrye occurred in pretreatment stands but was essentially eliminated from the burn and seed treatment plots within 1 year. Increased competition from seeded species may have been responsible for its decline. Four years after treatment, 46% of the total herbage production on this site consisted of seeded orchard grass (Dactylis glomerata) and slender wheatgrass [54].

Blue wildrye was among 5 grasses measured for canopy coverage before and after moist-fuel and dry-fuel underburns in an Idaho ponderosa pine forest. The underburns were conducted in experimental shelterwood logging units. No-burn, moist-burn, and dry-burn treatments represented a progression of heat treatments on the soil and surface vegetation. Total woody fuel consumption was 24% in the moist burn and 57% in the dry burn. Duff reduction ranged from a low of 10% in the moist sites to a high a 90% in the dry sites. Preburn vegetation was measured prior to logging. In the moist-burn treatment all grass cover, including blue wildrye, was similar to the original vegetation. Also in the moist-burn treatment, blue wildrye responded similarly to the other grasses by showing an increase in canopy cover the summer following burning. In the dry-burn treatment, unlike the other grasses, blue wildrye had disappeared from the test plots by the summer after burning. Canopy cover of grasses other than blue wildrye was reduced or maintained, with the exception of rhizomatous pinegrass (Calamagrostis rubescens), which increased [81].

In a Wyoming study on a quaking aspen site, blue wildrye was among 3 dominant grasses tested for seasonal changes in understory live fuel moisture. Other dominant grasses were California brome and slender wheatgrass. Percent moisture content decreased "as expected" during the summers of 1981 and 1982, but 1982 had 6 times more precipitation than the previous year, leading to considerable variation in overall fuel moisture between the 2 years. Also, in the drier year, moisture content of the grasses averaged 41% higher in a closed stand than in the adjacent open stand, with curing time lagging behind the open stand by 3 weeks [11].

Although blue wildrye forage quality generally improves during the first postfire growing season [23], this may not always occur. In a Wyoming study of the effect of prescribed burning on nutritional status (crude protein and in vitro dry matter) of understory species in quaking aspen, nutritional content of blue wildrye did not differ between burned and unburned plots 3 years after prescribed burning [15].

Related categories for Elymus glaucus | Blue Wildrye