SEASONAL BEHAVIOR OF RAIN-FOREST VEGETATION. 



The relative constancy of temperature in the Blue Mountain Region, 

 together with the lack of a pronouncedly dry season, gives the peren- 

 nial plants of the rain-forest continuously favorable conditions for 

 vegetative and reproductive activity in so far as concerns these major 

 factors of the climatic environment. During my two sojourns at 

 Cinchona I became interested in the seasonal variations of activity in 

 the native trees and shrubs, and made observations which collectively 

 cover all months of the year excepting June. The resulting data 

 exhibit a diversity of behavior which would not be expected on a 

 priori grounds in a region of such climatic constancy. There is, 

 however, a season of relative rest in both vegetative and reproductive 

 activity from October until January. In these months there occurs 

 a total or partial fall of leaves from a few species of trees, and a small 

 total mass of growth and bloom in the woody vegetation as a whole. 

 It is significant that the months named are the most rainy and the 

 most heavily clouded months of the year, a consideration of far more 

 importance than their slightly lower temperature. From February to 

 September there is greater activity, and it is in these months that the 

 divergent behavior of the various forms is manifested. There are 

 several species in which the winter is not a season of growth rest, but 

 greatly outnumbering them are the plants in which the spring and 

 early summer are the time of greatest shoot and leaf formation. The 

 increasing number of sunny days in the months which follow the close 

 of the winter rainy season is equivalent to a much greater rise of 

 temperature for the plants than is indicated by the thermometrical shade 

 readings, and may well be responsible for an increased vegetative activity 

 which wanes considerably before the advent of midsummer. 



Following are described the principal features of the seasonal behav- 

 ior of the Blue Mountain vegetation. 



I found growth and blooming to go on continuously at all months of 

 the year in a number of under-trees and shrubs, including the following : 



Piper geniculatum. Malvaviscus arboreus. 



Piper fadyenii. Heterotrichum patens. 



Boehmeria caudata. Oreqpanax capitatum. 



Bocconia frutescens. Acnistus arborescens. 



Dodonsea angustifolia. Datura suaveolens. 



In Oreopanax capitatum there is a short check in activity in mid- 

 winter. In Datura suaveolens blooming occurs at intervals of three to 

 six weeks throughout the year, being sometimes followed by a complete 

 fall of leaves. 



A few of the larger trees also continue their activity throughout 

 the year : 



Ilex montana var. occidentalis. Psychotaria corymbosa. 



Solanum punctulatum. Miconia quadrangularis. 



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