476 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1963 



Arctic and exclude the barren grounds of the far north. For our 

 general purposes, however, we will use the term broadly, and the 

 idiosyncrasies of the Tundra will be largely ignored. 



Let us return to the Alpine for a botanical look. By simple exten- 

 sion of what has already been said about the Arctic, we can now go on 

 to say that the Alpine comprises the treeless zone of high mountains. 

 Alpine vegetation is in many ways quite tundralike, as anyone who has 

 seen both the Alpine and the Arctic can testify, and, in fact, some plant 

 ecologists go so far as to use the same term. Tundra (or Tundra For- 

 mation), for arctic-alpine vegetation in general, calling the one "Alpine 

 Tundra" and the other "Arctic Tundra" (Costing, 1956). We can- 

 not digress to argue the merits of this view or any other except for a 

 few comments. Profound differences separate the Arctic from the 

 Alpine, as anyone who has done research in both knows, and 

 in any thorough-going scientific analysis these differences could 

 not justly be ignored and glossed over by one simple terminology. 

 Yet in the worldwide context of climates, floras, and vegetation one is 

 amply justified, I believe, in thinking singularly of one environment, 

 one flora, and one type of vegetation common to both the Arctic and 

 the Alpine, as I am doing in part here. Without other modification, 

 however, I will use the proper term "Tundra" only for the Arctic, as 

 in widespread usage. 



In the final analysis we are not so much concerned here with a care- 

 fully circumscribed area as with a concept. Whether, for example, we 

 define the Arctic by latitude, landform, isotherm, or vegetation type, 

 all definitions tend to converge on roughly the same area around the 

 Pole. What is far more crucial than a specific area is the concept of 

 environment and vegetation in concomitant transition. Relative to 

 organisms of ordinary tolerances, the environment gradually becomes 

 more rigorous and hostile as one moves poleward or upward from sea 

 level, and this transition is accompanied by gradual changes in the 

 vegetation toward ever more hardy types. The opposite ends of the 

 transitions are strikingly different, but the changes in between are for 

 the most part too subtle to permit the delineation of sharp boundaries 

 between one zone and another. If, however, a definition is necessary, 

 then let us think simply of the Arctic as being north of treeline and the 

 Alpine as being above treeline. 



Treeline, by which is meant here the upper limit of continuous forest, 

 is seldom a sharp line either in the Alpine or the Arctic, at least 

 when seen close up. Unless there are very steep or abruptly dis- 

 continuous changes in topography or climate, the proverbial tree- or 

 timher-Une is more likely to be a band or broad zone, which in the 

 Arctic may be many miles wide, where trees only gradually thin out 

 from forest to scattered clump and finally give way to open meadows 



