Revegetation of Soil 259 



THE RECLAMATION OF SOIL BY VEGETATION. 



F. M. Andrews, Indiana University. 



An exceptional opportunity afforded itself to make a study of the 

 reclamation of soil by vegetation on a small scale, as will be set forth 

 in this paper. In most cases of this kind the original conditions either 

 are not known or one is so situated that he is unable to follow the 

 progress of the revegetation of a given area. However, some cases are 

 on record where the observer is not hampered by the above mentioned 

 adverse conditions. 



An extensive and admirable study of revegetation has been made 

 by R. F. Griggs', who investigated the encroachment of plant life on 

 the materials thrown out by volcanoes. Instances of this and other 

 kinds of revegetation are also mentioned by Schimper". That seeds of 

 plants may be carried long distances by both air and water is well 

 known. The proper elucidation, however, of many of the conditions 

 involved in such dissemination has been especially well studied and 

 reported by Schimper who observed that seeds may be carried long dis- 

 tances not only in the above ways, but also may they withstand adverse 

 conditions during such carriage. 



Treub^ has also proved that spores and seeds can be carried long 

 distances, at least 20 nautical miles, for he found the spores of 11 ferns 

 and the seeds of two species of Compositae that distance inland on 

 Krakatoa. Wallace' mentions instances of seed distribution and revege- 

 tation. Numerous instances could be recounted illustrating the capa- 

 bility of plants to obtain a new locality and grow and finally take pos- 

 session of a given area. 



That many plants will gain a foot-hold and grow in unfavorable 

 conditions is in some instances well known. One such case the writer 

 observed on the slopes of Mount Vesuvius, when a few years after an 

 eruption, certain small trees and other plant life were growing on and 

 among the cooled lava and ashes, on a surprisingly unsuitable surface. 

 These plant forms were, of course, carried almost entirely by the agency 

 of the wind and some of them for considerable distances. The vegeta- 

 tion here decreased rapidly from the base of Vesuvius upward until 

 finally conditions were such that no plant growth was possible. 



But one does not always find it necessary to study such a problem 

 at a distance or over a large area in order to see the same factors at 

 work, even if on an infinitesimally smaller scale. One of the difficulties 

 is to find an area where complete plant denudation has been effected. 

 The re-establishment of the plant forms in a very small area, as in 

 large ones, can be seen in most cases to be extremely irregular in its 



1 Griggs, R. F. The Valley of 10000 Smokes. National Geographic Magazine, Vol. 

 31, 1917, pp. 13-68, and literature there quoted. 



- Schimper, A. F. W. Pflanzen Geographic auf Physiologischer Grundlage, 1898, 

 15p. 33, 200, etc., and the literature quoted in this work. 



' Treuh, M., in Schimper's Pflanzen Geographic auf Physiologischer Grundlage, 

 1898, p. 200. 



■> Wallace, A. R. Island Life, 1892, p. 77. 



"Proc. Ind. Acad. Sci., vol. 33, 1923 (1924;." 



