layer on the soil surface probably is effective in reducing the 

 number of species of plants that can thrive under Coast Redwood 

 trees. 



Study of the soils and past history of Coast Redwood forests 

 indicates that these forests have been subjected to periodic burn- 

 ing and also to periods of heavy silting as a result of floods (such 

 as the periodic floods that have devastated the redwood region in 

 recent years). These two ecological factors are probably very im- 

 portant in eliminating potential tree competitors of Coast Red- 

 wood. Coast Redwood is fairly tolerant of fires, and even young 

 plants can produce new shoots from the roots or lower trunks 

 if the upper portions of the tree are completely destroyed (Plate 

 7B). Some of the potential tree competitors of Coast Redwood 

 are not fire tolerant, however, and are completely destroyed by 

 these periodic fires. Furthermore, Coast Redwood can tolerate 

 silting by floods since the species can produce new surface-feeding 

 roots either by developing new roots from the old ones after they 

 have been buried under silt, or by the production of completely 

 new roots systems from the trunks of the tree just below the 

 surface of the silt deposit. In contrast, some of the potential tree 

 competitors of Coast Redwood are intolerant of silting and die 

 very soon after their roots have been covered by the layer of silt 

 deposited during floods. 



The potential tree competitors of Coast Redwood over much 

 of its area of distribution are Tan Oak, Douglas Fir, Grand Fir, 

 and California Bay. None of these species is very tolerant of 

 either silting or fire. Even if individuals of these species become 

 established in an undisturbed Coast Redwood forest, they are at 

 a competitive disadvantage compared with Coast Redwood. For 

 example, California Bay is a relatively slow grower and rather 

 intolerant of shade. Consequently, one rarely encounters a full- 

 grown or fully vigorous California Bay tree in a well-established 

 Coast Redwood forest. Douglas Fir can compete successfully 

 with Coast Redwood if both species start out simultaneously in 

 an area as seedlings, but Douglas Fir will eventually disappear 

 from the area due to the shorter life span of this species and be- 

 cause its seedlings cannot become established in the dense shade 

 of Coast Redwood. Similar explanations can be offered for other 



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