Bui. 1423, U. S. Dept. of Agriculture 



Plate 18 



Fig. I.— Lichen Quadrat, Untouched 



Area established for study at Uiialaklcct, Ala.'ika, April, 1922 



Fig. 2.— Lichen Quadrat, Cover Removed 



Same area as iu Figure 1. I'liolographcd aflor vcpolation had been removed by i)icliiiig, to 

 uolc the later recovery 



