﻿MOORE— SUCCESSION 



The soil is a light brown, pebbly sand of coarse texture, with 

 the upper 2-3 inches darkened by humus. The glacial origin of this 

 soil is attested by the planed surfaces of the pebbles. In one place 

 where the pine bordered an open field, a small piece, not over 50 by 

 100 feet, had been clear-cut sometime ago, perhaps 15 or 20 years. 

 Here the ground has been taken possession of by aspen, on the field 

 edge of which is a little gray birch (Betula populifolia Marsh.), con- 

 siderable white oak and black oak, and a little post oak; scrub 

 oak is mixed thickly with the aspen. The soil here was found to 

 contain a considerable amount of clay or fine silty material. 



That the clay or fine silty material is the cause of the aspen can- 

 not be stated definitely, for the pine was there before the aspen, 

 and might again take possession, as shown by pine seedlings on 

 spots which had escaped fire. Furthermore, in another part of 

 the forest, where the pine formed a fairly full stand except for 

 occasional small openings made by trees which had been weakened 

 by fire and then killed by insects, occur young aspen, gray birch, 

 and sycamore (Platanus occidentalis Linn.). The soil here, at least 

 down to 10 inches in depth, is the same coarse sand without clay 

 as was found under the other parts of the pine forest; but, owing 

 to the closer canopy of pine, there was a better mulch of needles, and 

 a considerable quantity of humus in the first 4 inches of soil. It 

 might be deduced that the extra mulch and humus here served 

 the purpose of the clay, but it is dangerous to jump at conclusions 

 from such observations. Clay might lie at various depths, being 

 near enough to influence the vegetation in some places and not in 

 others. Clay 2 feet below the surface would be sufficient to account 

 for this second case of aspen and other deciduous trees. Judgment 

 in this case must be withheld, therefore, until after further investi- 

 gation. 



Not far from this first body of pine, separated from it by a 

 cultivated field, we find an open stand of pitch pine in which are 

 scattered mature white oak trees, the understory being scrub 

 oak. The white oak appears to be about the same age as the pine, 

 but less numerous. The original stand, before fires became so 

 frequent, was probably chiefly pine with a scattering of white 

 oak. Here is what might appear at first sight to be an indication of 



