April 8, 1921] 



SCIENCE 



325 



VEGETATION MAPPING 



The value of accurate maps of native vege- 

 tation as a basis for very practical gen- 

 eralizations can not be questioned. It is ob- 

 vious that an essential condition for getting 

 accurate maps of large areas is the existence 

 of precise maps of smaller component ones. 

 At present very few precise local maps are 

 available, but it is to be hoped that botanists 

 throughout the country will begin to supple- 

 ment the efforts of a few of their number who 

 are doing map work of permanent and general 

 value. 



careful tests, and are presented not because of 

 any imagined novelty but because they may 

 prove useful to other workers under suitable 

 conditions. 



In original surveys of the forested states 

 by government engineers the bearing trees at 

 section corners were often listed by species, 

 while field notes of transects present an 

 orderly panorama of forest types passed 

 through on each mile. The first Ohio sur- 

 veys were generally done by trained woods- 

 men, and exhaustive field cheeks show that 

 their specific determinations of trees may be 



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The workers who have contributed our 

 various large area maps doubtless realize 

 better than any one else the impressionistic 

 nature of their final product. In most cases 

 these men have done the utmost possible with 

 scanty and vagnie local data. There have 

 been, however, a few instances of buoyant dis- 

 regard of the deadly principle of accumulation 

 of error which ought not to have happened. 

 One author, mapping a fairly large area, 

 secured local data from a source whose au- 

 thority few would care to question and then 

 from his distant vantage point cut and 

 trimmed until, speaking mildly, the accuracy 

 of a considerable sector of his map was 

 seriously impaired. 



In preparing careful local maps of vegeta- 

 tion the question of procedure varies greatly, 

 and is seldom an easy one. The two sources 

 of help outlined below have been put to rather 



pretty generally relied upon. Happily, too, 

 there have been few serious errors in running 

 lines — certainly nothing like the gross blun- 

 ders of some of the surveyors of a later 

 day who worked in states farther west. When 

 one considers the genuine hardships and 

 dangers unconsciously revealed by the field 

 notes covering the Connecticut Western Re- 

 serve (done before 1800), for example, the 

 excellence of the work is remarkable. 



A means of utilizing these notes has been 

 worked out after some experiment, and com- 

 bines economy of time with accuracy. A set 

 of arbitrary generic symbols was devised 

 which could be logically grouped and readily 

 memorized. Three typical series of symbols 

 are shown in the accompanying table. They 

 consist of familiar units of penmanship and 

 can be written without much effort, while 

 their number can be increased to cover almost 



