WEATHER CONDITIONS AND PLANT DEVELOPMENT 
GEORGE P. BURNS 
Vermont Agricultural Experiment Station 
The effect of weather conditions on plant development has been 
one of the chief problems studied during the past few years by the 
ecologist, the agriculturalist, the forester and in some cases by the 
plant physiologist. The weather, however, is a variable mixture 
composed chiefly of different amounts of light—direct, diffuse, white, 
yellow, red, etc., or darkness; moisture—precipitation, humidity, 
soil-moisture, etc.; heat, temperature of the air and soil; wind, etc. 
Each of these component parts varies within short intervals of time 
and each has its effect direct or indirect on the living plants. The 
problems of the effect of weather conditions, then, is largely a physio- 
logical problem and such problems should be attacked only by means 
of accurate experiments under controlled conditions. 
The ecologists have been attempting to change from the old 
descriptive methods in which the results of a more or less accurate 
study of the vegetation of a given area were published. Sometimes 
this study was accompanied by a few tables of meteorological data 
gathered from a nearby U. S. Weather Bureau station. In only a 
few cases were attempts made to relate these data to the descriptive 
part of the study and one was often at a loss to know why they were 
included in the publication. This type of work has served a good 
purpose in a preliminary way but is now outgrown. More accurate 
methods have been introduced by advanced workers and ecologists 
have adopted the plan of gathering their own data with instruments 
placed in the field, the attempt being made to place them under the 
same weather conditions as those of the plants under consideration. 
The largest amount of data has been collected on evaporation rates 
by workers with atmometers. This is probably due to the fact that 
these instruments are inexpensive as compared with the cost of the 
recording instruments necessary for collecting other data. But they 
lack standardization, many kinds, shapes and sizes being in use. 
Since no atmometer can be made to work exactly as a plant, ecologists 
should adopt arbitrarily one type in order that data wherever col- 
lected may be compared. Some ecologists have gone deeply into this 
phase of the work and are well equipped with field instruments record- 
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