MOSS RESPONSE 



The dominant species of moss colonizing the burn im- 

 mediately following the fire resulted from spores (table 

 15) borne by the wind from off site sources. Such mosses 

 initially spread vegetatively. Spores survived and ger- 

 minated best in sheltered microsites. The liverwort Mar- 

 chantia polymorpha also colonized the burned area 

 although it was infrequently found in Pattee Canyon 

 prior to the fire (McCune 1978). Propagules may have 

 come from residual Marchantia populations in moist 

 ravines for the initial colonizing populations in 1978 and 

 the recolonizing populations in 1980. 



Response of Seeded Grasses 



The four perennial grasses seeded on the burn are 

 either bunchgrasses or sodforming grasses. Orchardgrass 

 established best and has been the major species of seed- 

 ed grass present in all burn areas. When these grasses 

 were seeded, it was anticipated that orchardgrass would 

 be the strongest competitor and that it would be 

 naturally lost from the site in 10 years, or at most in 20 

 to 25 years. Seedlings of orchardgrass were present in 

 1981, indicating some ability to reproduce on this site. 

 Wheatgrass (Agropyron trichophorum and A. in- 

 termedium) has increased its (low) canopy cover since 

 1978. It has not been determined if this is the result of 

 seedling production. 



COMPETITION BETWEEN SEEDED GRASSES AND 

 NATURAL REVEGETATION 



The competitive impact of orchardgrass has been 

 strongest and most obvious in the moist, lower ravines. 

 In these areas the orchardgrass has grown very lush and 

 tall, shading and suppressing low shrubs and other 

 herbs. Conversely some plots were observed where 

 orchardgrass £ind other seeded grasses were shaded and 

 evidently retarded by the vigorous regrowth of 

 resprouting tall shrubs. 



The impact of grass seeding on upland sites is not so 

 easily observed. Data suggest that seeded grasses com- 

 pete and may suppress other species. The grasses shade 

 other vascular plants and compete for nutrients and 

 moisture by aggressive fibrous roots. There is at present 

 insufficient conifer regeneration to reach any conclusions 

 about the impact of orchardgrass on conifer regenera- 

 tion. In his discussion of the moss layer, McCune (1978) 

 stated that "the herbaceous layer (orchardgrass and 

 pinegrass) sufficiently moderated the microclimate near 

 the ground to allow more survival of the young mosses 

 during dry periods." By 1981, however, mosses were 

 becoming buried in the grass litter and spore production 

 was high (McCune 1981; personal communication). 



EROSION CONTROL 



Erosion control was a primary purpose for the grass 

 seeding project in the Pattee Canyon bum. Our studies 

 were not, however, designed to moniter erosion, nor were 

 they designed to evaluate the effect of seeded grasses on 

 erosion. Casual observations by study participants in- 

 dicate that accelerated erosion was not apparent during 

 the first 2 postfire years. 



During late May of 1980, several days of above normal 

 rainfall resulted in the flooding of Pattee Creek. Visual 

 inspection of the burned area following the flooding in- 

 dicated that some soil movement did occur on the steep 

 upper slopes, especiedly between clumps of orchardgrass 

 and other vegetation. The lower slopes, however, showed 

 little or no apparent erosion. The unseeded area (fig. 3) 

 showed no apparent evidence of erosion following the 

 1980 storm. Further comments on the benefits of 

 seeding grasses are found in Crane and Habeck (1982). 



WILDFIRE HAZARD 



Wildfire hazard in the burned area has changed 

 drastically as a result of the fire and subsequent grass 

 seeding. Removal of the forest canopy and most downed 

 woody surface fuels by the fii-e has eliminated the prob- 

 ability of moderate-to-severe fires for many years to 

 come. The probability of a fast-spreading, low-intensity 

 surface fire does exist as a result of the grass seeding. A 

 nearly continuous mat of dead grass covers most of the 

 burned area. During late summer, after the current 

 year's crop of grass cures, a fire could sweep the area. 

 The result of such a fire would be to set back tree and 

 shrub revegetation. 



Summary 



On the Pattee Canyon burn the initial vascular vegeta- 

 tion is derived from two main sources; preburn vegeta- 

 tion and seeded grass. (1) At present the most com- 

 petitive species appear to be orchardgrass and pinegrass, 

 with orchardgrass presently dominant in most areas. (2) 

 In ravines and those upland sites with prefire shrub 

 cover the shrubs have achieved dominance fairly rapidly. 

 (3) It appears, however, that secondeiry colonization by 

 shrubs wiU be necessary on many upland sites in the 

 burned area before a shrub stage as defined by Lyon 

 and Stickney (1976) could occur. (4) The recovery of 

 understory plants has been much more rapid in the 

 ravines than on any upland sites. (5) Tree regeneration is 

 at present scarce on most of the burn. Given the 

 distance from seed trees to much of the burned area, it 

 appears that regeneration of conifers may be very slow. 



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