The Coconino sun., 1924-11-07

grama is characteristic desert grass
and is therefore of increasing import
ance toward the west and south. dis
appearing altogether at higher eleva-
tions and toward the east. !.
The tall grasses have nearly all
disappeared from vast areas in north
ern Arizona as a result of heavy over
grazing, the sand dropseed (Sporobo-
lus cryptandrus) being the only one
which is still widespread and Wnlch
will come back readily if conditions
permit. In certain favorable areas
the western wheat grass (Agropyron
smithii) Is still predominant, and
such areas are of great importance,
because of the excellent quality and
large quantity of the forage produced.
This wheat-grass is especially I'M
portant also because wheat-grass
withstands grazing and trampling by
cattle very we'll in the situations
where it has survived, and because the
type contains sand dropseed, which re-
covers quickly If given opportunity.
The two types Of grassland men
toned (the tall grass, characterized
by the western wheat grass; and the
short grass, characterized by blue
grama) are the most important OF
those found grazed by prairie dogs IN
this region. The other types occur In
washes which flood to such an extent
that prairie dogs can not colonlZe
them, on rocky hills where these ro-
dents can not dig burrows, or in the
parks in the upper plant formations
where the animals can not live. Inc
short-grass forage types belong es-
sentially to the same formation ana
were originally much more closely as
sociated. The coming in of man with
his herds of grazing animals has
caused them to Segregate and form
iistinct considerations, or forage types
elements, 1920; Loftfield, 1924.
The experimental areas were estab-
lished during the early spring OF 1913
by the writer's, assisted by ID. A. Gli-
christ. After an extensive survey, the
Toconino area was selected as typl-
cal representation of the tall-grasS
vvpe, and the Seligman area OF that
form Of the short grass most common
lv found in northern Arizona. An
other tract was considered in the type
where blue grama is associated with
ring grass, since this was more nearly
representative of the short grass as II
occurs generally in the western states.
An additional installation was made
possible in a tract located IN the
;hort-grass type and established un-
der Mr. Gilchrist's direction on the
rusayan national forest, near VIII
liams.
Summarizing, the Coconino areas
are representative of conditions IN the
tall grass; Williams, those IN the
;hort grass; and Seligman, of tie
zone of transition between the great
plains and desert associations OF the
grassland climax. Results to 1922
from the Coconino and Williams areas
are presented, data from the Sellgman
areas being omitted because expert
mental difficulties have so Tar pre-
vented the securing of significant data
on rodent damage.
The CocOnino Experiment
The Coconino experimental tract is
situated near Coconino, Arizona, in
the northern division of the Tusayan
national forest, l mile east of the Will
liams-G Grand Canyon road. and about
8 miles by road from Grand Canyon
postoffice. The place selected is IN
The "wash, VINO hrs best described
as a water-made park IN the yellow
pine forests which forms broad belt
along the south rim of the Grand
Canyon at this point. The character
istic vegetation of the area (Pls. and
III is the western wheat grass (Agro-
pyron smithii) (Pl. IID, sparsely dot
ted with bushes of the true sagebrush
(Artemisia tridentata). The wheat
grass is predominant, but where some
protection permits it to produce seed
the sand dropseed (Sporobolus crypt
andrus) is of nearly equal Importance.
Blue grama (Bouteloua gracllls) II.
IV) is present also, but thus Tar has
been of minor Importance. Several
other grasses, such as the June grass
(Koeleria cristata), occur but are rare
and of little economic Importance.
Two plots were measured off on
April Id, 1918, each approximately
three-fourths of an acre in extent
(132 by 247.5 feet). One quadrat was
staked out and charted in each OF the
plots and another outside. The plots
we're fenced on May 27, 1918. To ex-
clude stock, four strands of barbed
wire were utilized. For the prairie
dog inclosure strip of 1-inch-mesh
galvanized wire feet wide was used
in addition, the lower 6 inches being
buried in the ground, leaving 212 feet
above the surface as barrier to the
rodents. -
Careful counts indicated the infes-
tation of prairie dogs in this region TO
be about 25 individuals to the acre. a
like proportion, or Is or 20 animals,
were found to have been fenced in the
inclosure. Prairie dogs in the total
protection area and outside the in
closures were eliminated by thorough
poisoning. Some difficulty was ex-
perienced in retaining the rodents
where needed and in excluding them
from protected areas, and this con-
stituted source of error in the ex-
periments, but these, tending to mini
mize rather than exaggerate the re-
sultc show the damage as less eX-