NOTES AND COMMENT 



Professor Robert F. Griggs has made some observations on the Sitka 

 spruce (Picea sitchensis) at the northern limit of forest on Kodiak Island, 

 Alaska (Bull. Torr. Bot. Club, July, 1914), and he is able to confirm the 

 statement of Fernow that this tree is now advancing northward onto 

 the tundra. Griggs states that the edges of forests have been used more 

 than have any other vegetational lines in shoAving the correlation of 

 plant ranges with climatic factors, and that they have afforded the "evi- 

 dence upon which most of the assumptions of static plant ranges have 

 been based." 



It is necessary here to ask who it is that has assumed plant ranges to 

 be static. Biology, in fact science in general, was formerly full of static 

 phenomena, but they have been kineticizcd at a rapid rate during the 

 last fifty years, and there are surely few plant geographers who still 

 maintain that plant ranges belong in the ancient limbo of things not 

 yet discovered to be unstatic. 



Griggs holds that the correlation of i)lant ranges with climatic fac- 

 tors is based on an assumption of complete adjustment of plants to cli- 

 mate and loses its significance wherever such adjustment does not exist, 

 i.e. wherever the ranges are not fixed but changing. To say that plants 

 are adjusted — or adapted (old style) — to climatic conditions is to state 

 an incontrovertible fact. To maintain that they are in a state of com- 

 plete adjustment is to say more than any worker has ever had the te- 

 merity to claim or the evidence to disprove. 



The relation of plants to climate is one which involves three variables : 

 the amplitude of the physical requirements of each species, the acquisi- 

 tion of new requirements or endurances by a plant stock, and the minor 

 and major variations of the climate. The ecological work of the last 

 fifteen years has centered in a study of the most unstable plant com- 

 munities, and Httle has been done until recently to correlate the succes- 

 sional phenomena in these communities with the physical conditions. 

 The observation of plant successions has been an easy task and has 

 afforded much aid in the classification of the communities involved. 

 The regions in which relatively stable vegetational conditions obtain 

 are mereh' the ones in which a more stable physical environment has 



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