879 
Woods of North-Easi Kent. 
The Thanet Sand consists of a fine light-coloured sand without 
pebbles, and gives rise to a light, frequently loamy soil. Chemical 
analyses show a small amount of calcium carbonate varying from 0*02 to 
0*38 % (Hall and Russell ( 7 )), and the soil in these woods generally gives an 
acid reaction with litmus paper. 
The woods in almost all cases consist of coppice, generally without 
standards, frequently made up almost of Chestnut (Castanea sativa , Mill.)* 
Hooker, in his ‘ Students’ Flora of the British Islands ’ (8), places the Chest¬ 
nut in the list of excluded species, and it is highly probable that the 
whole of these coppices have been planted. In this part of England mature 
specimens of the Chestnut only produce ripe seed in unusually long and 
warm summers, and in the case of the coppice, where felling takes place 
about every fourteen years, seed is only rarely ripened. No seedlings have 
ever been found. The regularity in the distance between the stools may 
also be given as evidence for the artificial origin of this type of woodland. 
Although stones are not found in typical deposits of the Thanet Sand, 
in several cases soils described in the Geological Survey as belonging to this 
formation contain a considerable proportion of rounded pebbles. Soils of 
this kind are usually found in proximity to the Woolwich and Reading beds, 
and in these cases a certain amount of admixture has probably taken place 
between the two formations. The vegetation occurring on such soils 
differs in some respects from that found on the typical deposits. Certain 
differences are also found in the flora where the Thanet Sand thins out 
in the vicinity of the Chalk. These variations in the composition of the 
vegetation, although seen both in the light and in the shade flora, are more 
pronounced during the shade period. This circumstance is not unexpected 
when the conditions under which the light flora is produced are considered. 
During the shade period little or no change takes place either in the abun¬ 
dance of the ground flora or in its composition. The factors on which its 
existence depends are almost constant, and in consequence the vegetation 
is in a condition of equilibrium. As a result of felling, large areas of almost 
unoccupied soil are rendered available for plant growth, and these are 
rapidly seized upon by species which possess an efficient method of distribu¬ 
tion. 1 Although many of these plants are doubtless well adapted to the 
soil composition a considerable number are probably enabled to develop, 
not because of the special suitability of the soil, but rather on account 
of the slight competition existing for a short period after felling has taken 
place. The occurrence of ruderal plants similar to those mentioned in the 
light flora of the Clay with Flints is probably rendered possible by the 
feeble competition during the first few years of the coppice growth. 
It is improbable that the light flora ever attains a condition of equi¬ 
librium. The elimination of the more unsuitable species will proceed for 
1 The origin of the light flora will be discussed in a later communication. 
3 M % 
