UNITED STATES DEPARTMENT OF AGRICULTURE 



s^r?'*r*j-u 



% BULLETIN No. 1059 M 



Contribution from the Forest Service 

 WILLIAM B. GREELEY, Forester 





Washington, D. C. 



May 19, 1922 



RESEARCH METHODS IN THE STUDY OF 

 FOREST ENVIRONMENT. 



By Carlos G. Bates, Silviculturist in Charge of Fremont Forest Experiment 

 Station, and Raphael Zon, Forest Economist. 



CONTENTS. 



Introduction .» 



Object 



Scope 



Sample plot method 



Need for a permanent organiza- 

 tion in forest investigations — 



Forest experiment stations 



Short-term studies 



The simple physico-physiological 



concept 



Measurement of environmental con- 

 ditions affecting vegetation 



Climatic characteristics of local- 

 ity 1 



Natural climatic regions 



Data obtained by the Weather 



Bureau 



Knowledge of existing stations 



necessary 



Periods of growth and rest 



Special observations on climate 



and soil of locality 



Location of instruments for 



study of growth 



Location of instruments for 



study of reproduction 



Air temperatures 



Problems 



Exposure of thermometers — 

 Standardizing thermometers 

 Maximum, minimum, and cur- 

 rent temperatures 



Hourly temperatures 



Croats 



Mean temperatures 



Annual summary 



In I run. '-ill - 



Soli temperatures 



Purpose* bo be served 



Problems 



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IS 



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Page. 



Measurement of environmental con- 

 ditions affecting vegetation — Con. 

 Soil temperatures — Continued. 



Time of observations 



Daily mean soil temperatures- 

 Readings 



Tabulation 



Hourly soil temperatures 



Summary of soil temperatures. 

 Annual summaries of soil 



temperatures 



Apparatus 



Special suggestions on surface 



measurements 



Instruments 



Solar radiation — light 



Concept of the functions of 



radiant energy 



The nature of sunlight 



Horizontal and vertical ex- 

 posures 



Total radiation on the site — 



Isolation under canopies 



Light measurements in rela- 

 tion to minimum require- 

 ments 



Apparatus and methods for 

 radiant energy measure- 

 ments 



The radiometer 



The thermopyle 



The bolometer 



pyrheliometers 



Thermometric sunshine re 



••order „ 



Solar thermograph 



Photo chemical phol • 



ters 



Comparison photometers 



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4G 



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