﻿iai6] MOORE— SUCCESSION 



future investigations; and it is just this feature of the i 

 which needs emphasis. Conclusions from one locality should not 

 influence investigations in another locality, except in creating a 

 desire to test the conclusions. The answer should be: We do not, 

 and cannot, know until after thorough quantitative study of all 

 factors which so far as now understood may have a bearing on the 

 question. 



Meanwhile, until such an investigation is made, several features 

 of the situation, so far as they can be determined by observation 

 without detailed study, may be noted. It is conceivable that, if 

 conditions were left undisturbed for a sufficient length of time, the 

 pine would, by a gradual accumulation of humus, render the soil 

 favorable to the oaks, 5 which would then crowd out the pine. But 

 in nature, conditions, at least in forests, are never left undisturbed 

 indefinitely, for if man does not start fires lightning will, and fire 

 tends to produce a deadlock between the pine and the oak. It 

 favors the oak against the pine in that the oak seedlings which are 

 killed can come up again from sprouts, whereas the pine seedlings 

 cannot. On the other hand, it favors the pine against the oak by 

 destroying the physical conditions, especially the litter and humus, 6 

 favorable to the oak. The result is that a worthless form of oak, 

 the scrub oak (Quercus nana), which both is fire-resistant and can 

 grow on sandy soil, takes possession of the ground. Above the 

 scrub oak is seen an occasional pine or an oak, most frequently a 

 white oak, owing to its greater power of fire-resistance. 



It might be noted here that the scrub oak, owing to its dense 

 habit of growth, protects the soil against leaching out, as well as 

 serving as an excellent accumulator of humus. It appears to be 

 analogous to the snowbrush and manzanita in the northern and 

 central Sierras of California. These species and their associates, 

 which should not be confused with the true chaparral farther south, 

 form a dense cover of brush about 4-8 feet high, which keeps the 

 soil and lower atmospheric strata favorable for the establishment 



Sarg.). 



6 It has been found by R. C. Hawley by quantitative experiments that repeated 



