Figure 2.— Aerial photograph of the surface mine of the Arrowhead Coal Company in North Dakota, showing subsidence over 

 the old abandoned underground mine workings in the background (Trimble, 1979). The highwall of the surface mine is 15 

 to 20 feet (foreground). Subsidence over underground room-and-pillar mines creates hazardous surfaces and destroys 

 agricultural land; it does, however, create a local wildlife habitat. Such areas are difficult or impossible to reclaim. 



to which fines from the coal were added. These 

 ridges, commonly called orphaned spoils, pro- 

 vide examples of the natural revegetation proc- 

 ess under the most adverse local conditions of 

 moisture depletion, temperature stress, and soil 

 instability. 



In North Dakota where adequate moisture is 

 available, some orphan spoils have, over a period 

 of 40 years, become naturally revegetated with a 

 variety of plant forms, mainly perennials. These 

 plants have formed islands of vegetation in the 

 mined lands and provide refuges for wildlife, 

 especially deer (figs. 9 and 10). In some places, 

 sportsmen and conservation groups have 

 planted woody vegetation on spoil piles specifi- 

 cally to create wildlife refuges, and the vegeta- 

 tion is doing well (fig. 10). Canadian experience 

 in converting old spoil piles to wildlife refuges 

 has been similar (Schumacher and others, 1977, 

 p. 19). 



Most steep slopes in western coal mined 

 areas, however, are generally bare of vegetation. 

 Elsewhere vegetation is restricted to the most 

 favorable germination sites, namely those where 

 the soil surface is flat enough or where benches 

 allow enough moisture to accumulate to support 

 seed germination. Except in the more humid 

 areas, plant cover is sparse even though some 

 native plants are beginning to colonize (fig. 11). 

 In some locations, moisture-collecting places 

 between the spoil piles and at the bases of old 

 highwalls and ponds are colonized by willows 

 and cottonwoods which may locally dominate an 

 otherwise barren landscape (fig. 7). 



Some mining companies attempted to stabi- 

 lize raw spoil piles by aerial seeding with either 

 grasses or legumes, or both. Some State regula- 

 tions required the leveling of the ridges (figs. -12 

 and 13). These newly leveled surfaces were then 

 partly seeded from the air and, in places, were 



