Jan., 1919] Effects of the Eruption on Vegetation 197 



most common readings were about 43 F. as compared with air 

 temperatures averaging about 50 F. Thus the temperature 

 beneath the heavy ash blankets on the mainland may be pre- 

 sumed to be in the neighborhood of 40. F, But the Equisetum 

 at Kodiak, which revived on being dug up, had been buried 

 only a few inches beneath the surface and must have been at 

 a temperature well above the growth minimum for several 

 months in each of the three years of its burial. Next to the 

 low temperature, one thinks of desiccation as a means of 

 maintaining a dormant condition in plants. But desiccation 

 cannot have been a factor in this case for the country is notor- 

 iously wet. Indeed, the Equisetum had lain below the water 

 table in all but the driest months of the year. One might 

 go on and consider the possible lack of oxygen and other fac- 

 tors, but there was nothing in the field to suggest the action 

 of such factors and no means available of estimating their 

 probable effect. 



There is some evidence that a similar dormant period may 

 follow the shock of an eruption even in a tropical country, where 

 the vegetation is not accustomed to such seasonal variations as 

 the plants of the Katmai District are subjected to by the long 

 winters. In the revegetation of Taal, which has been studied in 

 more detail than that of any other volcano up to the present, 

 Gates 7 found in October, 1913, nearly three years after the 

 eruption, only three clumps of bananas and none of bamboo. 

 But, "in April, 1914, bananas were fairly abundant and indi- 

 cated quite well the positions of many of the -former houses," 

 while bamboo was also prominent. Brown, Merrill and Yates 8 

 furthermore submit evidence which indicates that a large 

 proportion of the new vegetation of Taal may have come from 

 old roots which lay dormant for a long period. 



RESTORATIVE REACTIONS OF SURVIVING PLANTS. 



From what has been said above, it is evident that those 

 trees, which were not killed outright by the eruption, were so 

 injured that the chances of their ultimate recovery must have 

 appeared remote if they had been examined soon after the 



7 Gates, F. C. The Pioneer Vegetation of Taal Volcano. Philip. Journ. Sci. 

 Ser. C, 9: 391-434. Pis. 3-10. 1914. 



8 Brown, Merrill and Yates. The Revegetation of Volcano Island, Luzon, 

 Philippine Islands Since the Eruption of Taal Volcano in 1911. Philip. Journ. 

 Sci. Ser. C, 12 : 177-248. Pis. 4-16. 1917. 



