508 JOURNAI, OF FORESTRY 



position and the nature of their lumber products, has been generally 

 misunderstood by dwellers of temperate regions. Most people believe 

 them to be very complex in composition and to contain only hard and 

 very hard woods that cannot be generally substituted for the soft conif- 

 erous woods. It is true that from the standpoint of a botanist they are 

 very complex in composition — and to one unacquainted with the nature 

 of tropical forests the botanists' reports are likely to be misleading. 

 In the first place, in contrast with temperate regions, the great majority 

 of the species are woody, either trees or woody vines (lianes). More- 

 over, the tree species of the forest can usually be arranged into four 

 diiTerent irregular stories, depending on the size each species attains 

 when it is mature. The height of the different stories differs according 

 to the forest considered. In forests where the climatic and soil factors 

 approach the optimum for forest growth the lower story is composed 

 of tree species which when mature have a height of 15 to 30 feet. 

 These, together with the immature trees of the upper stories, make this 

 story most complex. The second story has trees, say, from 31 to 60 

 feet in height, the third those 61 to 100 feet, and the top those that are 

 over 100 feet, and in some instances up to 150 feet. In each successive 

 story from the lower up the number of species that have the inherent 

 power to reach the higher stories when mature becomes less ; so that the 

 top story has fewer species than the third, the third less than the second, 

 and the second less than the first. Obviously, the lumberman in sizing 

 up the forest from its capacity to furnish timber would consider the 

 trees of first and second stories, and in some instances the third story, 

 as weed trees, just as he would consider the undergrowth of a typical 

 deciduous forest in temperate regions as not worthy of his considera- 

 tion as producing lumber. Naturally, complexity of the upper story 

 varies according to the quality of the site on which the forest grows. 

 On many habitats the upper story consists of scattered trees here and 

 there that project the whole or a part of their crowns above the general 

 level of the story beneath, thus giving the profile of the forest an uneven 

 appearance. In such a case, if the other species of the lower stories 

 were removed, the forest would have an appearance not unlike the park 

 forests of the western yellow pine. Sometimes this upper story is made 

 up entirely of one species, or for a given region there may be as many 

 as 12 to 20 species. Usually, however, it is quite simple in composi- 

 tion. I observed a striking example of this on an island off the west 

 coast of Mexico, where at least 90 per cent of the individual trees were 

 of one species, known locally as palo prieto. The remaining 10 per 

 cent comprised a large number of species with scattered individuals 



