Jan., 1919] Effects of the Eruption on Vegetation 187 



PRESENT CONDITION OF SURVIVING TREES. 



Because of the difference in the habit of growth, the sur- 

 vivals among the various species of trees show quite different 

 degrees of injury. Balsam poplars (P. candicans)* were the 

 only large trees. All of the growing parts and all of the ordinary 

 buds of these were killed; but some of the dormant buds, 

 buried deep in the thick bark of the large branches, survived 

 and have grown out forming short, bushy brushes, which give 

 the trees a most outlandish appearance. (See page 185.) 



In some places it may be seen that the smaller trees survived 

 where the taller ones, standing beside them, perished. The 

 taller trees were, of course, more exposed, and protected the 

 smaller to a certain extent, but it is not obvious at first why 

 their own lower branches, which were protected to the same 

 extent as the adjacent saplings, have not survived. (See page 

 186.) Sometimes only a few buds on a very large tree have 

 survived. The most extreme case of this sort of thing observed 

 is shown on page 192. In other cases the bark is all dead except 

 for a very narrow strand up one side of the tree which supplies 

 the few new branches. (See page 198.) 



The alder, {A. sinuata), which is the most characteristic 

 Alaskan bush everywhere, was simply exterminated. Not until 

 we had explored a considerable part of Katmai Valley did we 

 find so much as a single live sprig of alder, and then we saw 

 only two or three small shoots coming up from the roots. 



The birch, {B. kenaika), the Alaskan representative of our 

 paper birch, has suffered only less severely than the alder. 

 Throughout the main valley it was destroyed, but in the 

 more sheltered conditions of Soluka Valley new sprouts from 

 the roots are fairly abundant. 



The Alaska willow, {Salix alaxensis), suffered less than any 

 other tree. In many places it has, in fact, almost completely 

 recovered from the effects of the eruption. This is probably 

 due to its capacity for forming adventitious roots on burial. 

 (See below, pages 200-202). The other willows, Salix nuttallii, 

 Salix barclayi, and Salix bebhiana have also recovered to a 

 considerable extent, though their new growth is much less 

 luxuriant than in Salix alaxensis. Salix nuttallii in particular 

 shows an interesting reaction of tops as well as roots. (See 

 page 201.) 



* The writer wishes to extend his thanks to Messrs. Paul C. Standley and 

 A. S. Hitchcock of the National Herbarium, who kindly verified the determinations 

 of the plants collected. 



