NORTHERN GREAT PLAINS FIELD STATION, 1913—1922 7, 
Clipped quadrats.—This name was adopted from the method of 
removal of the vegetation, which was cut or clipped close to the 
ground with a pair of roaching shears. In no case were the plants 
cut below their crown. The aim has been to cut all plants uniformly 
close to the ground, closer than they would be grazed by cattle. The 
plants were divided into different groups at each clipping. The 
clipping was done at different periods varying from 10 to 40 days, 
and annually, or at the end of the season. In 1919 a set of quadr ats 
was added for the removal of the vegetation every two years. The 
clipped quadrats plainly show that the most active growth and 
ereatest production of the vegetation as a whole is in May and June, 
the period during which the cattle make their greatest gains. Boute- 
loua gracilis is “the species most resistant to clipping. Quadrats 
clipped at 10; day intervals were discontinued at the close of 1921. 
During 1922 Bouteloua gracilis made a fair growth on them, and a 
few plants Thaadled| out. Stipa comata is the species least resistant 
to clipping. It has entirely disappeared from the frequently clipped 
quadrats. 
Isolation transects.—These areas were 40 feet wide and 300 feet 
long when first established. They were fenced when the pastures 
were started. One transect was located in the 30-acre pasture, one 
in the 100-acre pasture, and one in division B of the rotation pasture. 
On one side of the fenced area a unit 20 feet square was closed to 
grazing each year. On the opposite side a like unit was opened to 
grazing. The units in the center were never grazed. The transect 
in the 30-acre pasture shows the points of most value. The units 
on each side that have been grazed the longest show the largest 
number of plants of Artemisia “Frigida per unit area. In the units 
not grazed the plants of A. frigida remain normal in number and are 
not as coarse as those in the open pasture. 
Photographs.—Views of the vegetation and cattle have been taken 
each year since the grazing experiment started in 1915. Photo- 
eraphs are of unusual value in connection with this experiment, as 
they bring out certain points and illustrate features that do not lend 
themselves rea adily to description or measurement. 
Field notes.—Notes on the growth of the native vegetation are 
recorded each year. The time that any species starts growth in 
the spring is influenced by the season and may vary widely from year 
to year. There is also a wide variation between species in the time of 
starting growth. Bouteloua gracilis does not start its sprmg growth 
as early as most other grasses. Stipa comata and Koeleria cristata 
are the earliest grasses to start growth in the spring. 
Other inv estigations which were carried on as a part of the grazing 
experiment were a mowing experiment, field germination tests of 
grass seeds, seeding experiments in the native sod, and soil-moisture 
determinations. 
The acre units of the mowing experiment were so arranged that 
3 acres were mowed each season and 3 acres in alternate years. The 
yield of hay from all units has been low, but the units mowed in 
alternate years have produced approximately twice as much hay 
per acre as those mowed every year. The hay from the two-year 
units was not of as good quality as that from the one-year units, as 
about one-third of its weight was composed of the old growth of 
the previous season. 
