An 



Explanation 

 and Glossary 

 of Special 

 Terms 



Figure I 



Our planet as 



it would appear if 



there were no oceans 



or mountains and all the 



vegetational belts girdled it 



without interference. 



Wherever you travel on the land surface of this earth, sooner or later and usually in a very 

 short space, you will encounter what we call a change of scenery. This is so even in the midst 

 of what appear on maps to be featureless deserts, prairies, or even vast plains covered with 

 forest. The most notable aspect of this is the constant change in and variety of the land sur- 

 face as a whole, but this is not its only aspect. Often nothing about the topography of the 

 land changes but still the scene does, and drastically, so that even the least observant may 

 notice it. Such innovations (which may come either suddenly or gradually, either widely 

 spaced or in rapid succession) are due to changes in the vegetation; and they may be quite 

 stunning. 



Vegetation is the link that binds what Dr. Costing — as quoted in my Foreword — calls the 

 environment with the organisms, both plants and animals, and even ourselves. It is also a 

 key that can unlock many of the mysteries of nature that we encounter as we travel about the 

 land surface of our earth. 



VEGETATIONAL BELTS AND ZONES 



Within limited compass these are brought about by such circumstances as the availability of 

 soil moisture, but they also occur as a result of much more basic realities that are not so 

 apparent. Further, they need not. and very often do not, entail alterations of the botanical 

 character of the vegetation — i.e., in the kinds of plants — but in what is called the fades of 

 the vegetation itseK. As an example, one may be crossing a flat plain covered with shortish 

 grass and dotted with an orchard of only one kind of acacia tree of a rather grand stature, 

 when suddenly one finds oneself walking through the same grass but waist high and be- 

 tween the same trees but of a smaller size. None of the plants has changed, but the manner 

 in which they grow and their relationships have done so — even to the size, shape, and abun- 

 dance of their leaves. We have here entered what is called another facies. a geologist's term 

 that means "make, form, figure, or shape" and denotes to those specialists that a stratum of 

 rock has changed its appearance in space but not in time. This is to say that as it is followed 

 from one area to another — horizontally — it undergoes a change from, say, a fine clay to a 

 coarse sand. 



The study of vegetation as opposed to mere plant distribution is a special department of 

 phytogeography which actually has little to do with the distribution of individual species of 

 plants, or even of plant groups, genera, families, and so forth. While the presence of certain 

 plants may in some cases be important to the growth of other plants, such as parasites and 

 vines, it is invariably paramount in the distribution of animals, including man. However, 

 variations in botanical constitution are insignificant compared to those in the facies of the 

 vegetation and its distribution. Thus, in our orchard, the species of grass and of acacia are of 

 almost no importance, but the way in which both grow — their density, size, and so forth — is. 

 Even further, you can substitute almost any grass-shaped herb for the grass, and a palm or 

 almost any other tree — even a cactus — for the acacia tree, without affecting the animal life. 

 But step from an orchard into a forest or onto a savannah and, in a matter of paces, the 

 entire fauna may change absolutely. 



Such changes in vegetation are everywhere to be seen, and at first they appear to be arbi- 

 trary and often chaotic; but if one travels far enough, especially north or south or up a 

 mountain, it is apparent that there is a definite succession in their appearance. It is also mani- 

 fest that some are repeated and that others are not; and that similar facies occur at different 

 latitudes, or latitudes in different areas. Even a glance at a world map on which vegetational 

 types are displayed will demonstrate that the major facies — forests, orchards, savannahs, 

 scrublands, deserts, prairies, parks, tundras, et cetera — form continuous belts around the 

 globe, regardless of the seas and oceans that intervene between the land masses. However, 

 these major belts do not go round the planet in neat straight bands but waver to north and 

 south (in different phases in the northern and southern hemispheres) and expand and con- 

 tract in width as they do so. Further, just as they appear to "run under" or skip over the 

 oceans, so they also seemingly disappear into mountain ranges on one side and come out 

 unscathed, as it were, on the other. 



Closer examination discloses the fact that these belts are repeated in miniature in an 

 upward succession on all highlands and mountains, in exactly the same succession as they 

 are found at sea level going from the equator to either of the poles. Moreover, we find that a 

 very tall mountain standing on the equator will have all belts found between its base and 

 either of the poles duplicated as zones on its slopes, starting at the bottom in tall, wet, equa- 

 torial forest, composed of three or four tiers of evergreen plants, and ending at the top in an 

 icefield. By the same token, a mountain standing in. say, one of the hot deserts will display 

 only those belts that lie between the latitude where it stands and the nearer pole. Then 



