to 18 inches. Without fire this spruce is self- 

 perpetuating both by layering and seeding. Even 

 after a single intense fire it usually regenerates; 

 but if fires are repeated often, the area may be- 

 come a treeless community supporting sage- 

 rush-grass, or low shiubs. Reentry of black 

 spruce may then be very slow. The trees are 

 short, small in diameter, and have full-length, 

 narrow crowns. On excessively dry valley bot- 

 toms or low benchlands, black spruce tends to 

 grow in extensive areas of dense thicket type 

 stands 20 to 30 feet high, and be so dense that 

 human penetration is impossible. With its typi- 

 cal moss ground cover, a black spruce site is an 

 explosive fire type. Most of the excessive rates 

 of spread recorded on going fires occurred in 

 black spruce stands (ch. 7). 



Grass. — Grass, a typical flash fuel, is found 

 throughout Alaska from valley bottom to ridge- 

 tops and in unbroken continuity from small 

 patches to single areas of hundreds of square 

 miles. Grasses and sedges are an integral part 

 of all muskeg types. In southwestern Alaska 

 grasslands Calamagrostis may be 6 to 8 feet 

 high with a 1 2- to 15-inch surface accumulation 

 of down grass, or "rough." Fire spread in 

 Alaskan grasses is similar to that elsewhere. 

 Winterkilled grass burns at a flash rate of spread 

 in spring before new growth occurs. In late fall 

 after killing frosts, the spread rate again in- 

 creases. 



Muskeg. — Muskeg denotes a poorly drained 

 site regardless of where it occurs topographically. 

 It carries an association of heavy sphagnum 

 mosses, tussocks of sedges, grass, various heath 

 plants, brush, and black spruce,- minor surfaces 

 or better drained ridges within a muskeg may 

 carry birch or white spruce. The term "muskeg" 

 is also used to include swamps or bogs contain- 

 ing hundreds of potholes, sloughs, or lakes. 

 Wherever subsurface drainage is blocked, a mus- 

 keg association develops even on moderate 

 slopes and ridgetops. As an ecological term, 

 muskeg is limited generally to peat-forming 

 vegetation in Alaska and northwestern Canada. 



Moss found in muskegs may be from several 

 inches to several feet deep carrying recognizable 

 plant structure to those depths (peat does not). 

 The moss and lichen types comprise a specific 

 and difficult fire problem because their flashy 



USPS 



Figure 34. — Small black sprue* stand near Gulkana. 



USFS 



Figure 35. — Typical grass type on lower Kenai Peninsula. 



39 



