12 Forest Club Annual 



but the factor investigated, and the effectiveness of each deter- 

 mined. This being done, their influence must be integrated ; and 

 further, since under natural conditions climatic factors vary 

 widely both in intensity and in duration, facts of the highest 

 importance to life processes yet often overlooked by junior in- 

 vestigators, such variations must be taken strictly into account. 

 For example, a temperature of three or four degrees below 

 freezing lasting for only an hour 'or so is not necessarily detri- 

 mental to the plant, whereas, if the same low temperature main- 

 tains for several hours part or all of the superficial plant tissues 

 may be killed. On the other hand, freezing temperatures of rel- 

 atively short duration coupled with high winds may be fully as 

 harmful as noticably longer periods of similar minimum tempera- 

 tures. 



From the foregoing it is apparent that the direct determina- 

 tion of the response of vegetation to the controlling factors is a 

 problem of such detailed and far-reaching potentialities as to 

 involve not only infinitely more time than most field botanists 

 can devote to the problem but of necessity elaborate and costly 

 laboratory and field equipment. Further, a problem of this 

 character is hardly to be solved by a single investigator. It is 

 a study in which the plant ecologist, the physiologist, the mor- 

 phologist, the taxonomist, the physicist and the chemist might 

 well cooperate. 



The quadrat method of noting the correspondence between 

 habitat factors and vegetation while somewhat superficial, but 

 nevertheless reliable, may be used by any investigator. This 

 method of study, while tedious because of the necessary detail 

 involved, presents ocularly the integrated relationship existing 

 between the factors of the habitat and the vegetation, \\hile 

 this correspondence may be more or less apparent to the experi- 

 enced physiologist and ecologist absolute invasional and succes- 

 sional figures so essential to purely scientific studies and to the 

 practical management of lands are not available without a detailed 

 "pictorial" account of the vegetative structure and compositional 

 changes. The readiest methods available by means of which to 

 obtain these data are briefly stated. 



APPLICATION AND ESTABLISHMENT OF PERMANENT 

 SAMPLE PLOTS. 



The use of experimental plots, as applied in forestry investi- 

 gations, consists, in general, more of applying quadrat methods 



