Annual report of the Rocky Mountain Forest and Range Experiment Station, calendar year 1953

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ANNUAL REPORT

OF

THE ROCKY

MOUNTAIN

FOREST AND RANGE EXPERIMENT

STATION1f

CALENDAR YEAR 1953

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Headquarters at Fort Collins, Colorado, in cooperation with Colorado A & M College •

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C O N T E N T S Introduction Range Research

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Grazing management Range reseeding • • • Noxious plant control Forest Management Research . Forest Disease Research Forest Insect Research ••

Forest Utilization Service

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Page i 1 1 11

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Watershed Management Research • • • • • • • • 51 Publications • • • •

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• INTRODUCTION

The year 1953 was a momentous one for the Rocky Mountain Forest and Range Experiment Station. Three major events took place which have materially broadened the scope of the research program of the Station and facilitated the conduct of the work •

These events are as follows:

1. The consolidation of the former Southwestern and Rocky Mountain Stations into a new, enlarged Rocky Mountain Forest and Range Experiment Station.

2. The addition of Forest Insect Research and Forest Disease Research to the Station's program, as a result of the reorganization of the Department of Agriculture.

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The organization and conduct of the resulting enlarged research program on a problem area or research center basis.

Consolidation of the former South-western and Rocky_Mo_unt2in Stations

The Forest Service is constantly studying ways and means of keeping abreast of the times to meet changing needs and problems and for economy and efficiency of program operation. Hence, after thorough study during the past 2 years, it was deemed expedient to consolidate the former South-western and Rocky Mountain Stations into a new, enlarged Rocky Mountain Station. The areas served by these two stations have many problems in conunon so that basic facts from certain experimental areas will have wide application. Also, improved transportation and other facilities made consolidation possible •

Several advantages resulted from this move. Of importance among

these is that certain economies were made. The elimination of one Director's office now makes it possible to continue and generally strengthen the going research programs of the former two stations in the face of the constantly declining research dollar. Had this not happened, some of the essential research under way would have been curtailed or eliminated. Of importance, also, is that the consolidation of the two relatively small stations into one has made possible an enlarged, more comprehensive and more closely correlated program of research. Formerly, only partial programs in a few fields were possible at the two stations. Now, as a result of consoli-dation, research on a more adequate basis is under way in range management research, watershed management research, forest management research, and forest utilization. Thus, more skills and services are now available in the forest and range research field to the people and interests in the Southwestern ~nd Rocky Mountain areas.

The addition of Forest Insect and Forest Disease Research as a result of Dep~rtm~ntal reorgan!£ation

In accordance with Secretary Benson's memorandum of November 2, 1953, pertaining to the reorganization of the Department of Agriculture, Forest Insect Investigations, formerly in the Bureau of Entomology and Plant Q uar-antine, and Forest Pathology, formerly in the Bureau of Plant Industry,

Soils, and Agricultural Engineering, were transferred to the Forest Service and added to the programs of the forest and range experiment stations. This has resulted in two additional fields of research at the new Rocky

Mountain Station; namely, Forest Insect Research and Forest Disease Research. The addition of these two fields of research makes available skills and

services in six fields of forest and range research, and provides for better correlated and productive work in these closely allied fields.

As a part of the reorganization of the Department of Agriculture, certain phases of range research were transferred to the Agricultural Research Service. All range research in the Great Plains and that at the

Jornada Experimental Range in New Mexico was transferred. Also transferred was research in range reseeding except for wild game and the management of reseeded ranges and research on methods on control of undesirable range

plants except for control by grazing management or fire, and ecology studies. However, it is understood that the men conducting the research transferred are to remain in place and continue essentially as in the past on a coopera-tive basis. Cooperation with the Agricultural Research Service offers

additional skills and a broader basis for an overall range research program. Organization and conduct of research on

2.-Eroblem area or res~arch center basis

To effectively administer the broader and more comprehensive program of the Station within the enlarged area to be served, research is now

organized and conducted on a research center basis.

There are nine research centers within the territory served by the new Rocky Mountain Station, with active programs of research under way at each. These include the Santa Rita, Sierra Ancha, and Fort Valley Research Centers with headquarters in Arizona; the Upper Rio Grande Research Center with headquarters in New Mexico; the Upper Colorado River, Continental Divide, and Front Range Research Centers with headquarters in Colorado; the Big Horn Research Center with headquarters in Wyoming; and the Prairie Research Project with headquarters in Nebraska. Two other problem areas are recognized; namely, the Black Hills of South Dakota and Wyoming, and the Trans Pecos in New Mexico and West Texas which, because of lack of funds and facilities, are not yet activated.

In addition to the above research centers at which phases of forest and range management research are being conducted, the Forest Insect and Disease Research of the Station is organized and conducted from two Forest Insect and Disease Laboratories. One of these laboratories is headquartered at Albuquerque, New Mexico, and serves the States of Arizona and New Mexico. The other is headquartered at Fort Collins, Colorado, and serves the remain-ing portion of the Station's territory. Another Station function, the Forest Utilization Service, is headquartered at Fort Collins, and covers the entire territory.

The research center and laboratory basis of operation is not new. It has been followed by the Forest Service for the past 8 years in the eastern and southeastern parts of the United States. Also, some of the work at the former Southwestern and Rocky Mountain Stations has been on this basis for the pas~ 3 years. The organization, therefore, has proven

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to be effective and has several marked advantages. Among these are: (1) By reason of the research workers residing within the problem areas, they become more intimately acquainted with the people and the problems needing attention; (2) the people within the problem areas have a greater opportunity to take part in the programs; and (3) as a result, the

research results obtained are oriented to local problems and readily accessible to put into practice.

Mani worthw~ile results developed during the ~~r

Despite the consolidation of the two Stations into one and the reorganization of the Station and its program, research was continued throughout the year with a minimum of interruption. Many importan~ results were developed; the more important findings of the year are presented in the following pages under the several fields of research •

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RANGE RESEARCH

Range research has as its overall objectives the development of methods and techniques (1) for improving forage production on rangelands not now producing all the forage they are capable of producing, and (2) for managing ranges and range livestock to obtain the greatest possible produc-tion of livestock and livestock products and game animals consistent -wibh other legitimate uses of the land. To this end research is conducted on several phases of range management such as the growth and development of range forage plants, the management of livestock on the range, the utili zation of ranges by livestock, and the improvement of deteriorated ranges through proper livestock use, reseeding, and noxious plant control.

Progress on research on these phases is discussed under grazing manage-ment, range reseeding, and noxious plant control.

Grazing Managem~nt Prolonged drought in Arizona and New Mexieo adv~rse to forage and livestock E!:Oduction

Drought conditions continued to prevail in southern Arizona and New Mexico. In southern Arizona, for example, an analysis of rainfall records of 29 weather stations for desert grassland rangelands showed summer rainfall to be below average at 79 percent of the stations. Fourteen stations were considered to be experiencing severe drought conditions (3 to 10 years of consecutive below-average rainfall) and seven were experiencing moderate dro~ght conditions.

Lack of precipitation resulted in low forage production which in turn was reflected in increased cattle shipments and slaughter for southern Arizona during 1953. There was a 166-percent increase in disposal of cattle over the previous year, in spite of unfavorable market conditions.

The Jornada Experimental Range in southern New Mexico and the Santa Rita Experimental Range in ~outhern Arizona, both located in the semidesert grassland range type, illustrate some of the adverse effects of the prolonged drought on going range livestock operations.

Th~~rity of the drought increased at the Jornada Experimental Range in_l953~ making_l_£2.~~cutive years of drought.-- This is the most severe drought experienced at the Jornada since weather records were first taken there in 1915. Average summer rainfall for the 3-year period,

1951-53 inclusive, was 58 percent below the longtime average. The rainfall for July through September, the period when most of the forage growth is made, was 1.23 inches in 1951, 3.41 inches in 1952, and 1.46 inches in 1953

--only 53 percent of the longtime average. Furthermore, the meager rainfall of 1953 was poorly distributed. As a result, little forage was produced and some parts of the range that ordinarily produce abundant forage, produced no growth of perennial grasses.

Due to lack of forage growth, livestock numbers on the Jornada were further reduced. Only 58 head of cattle and 25 horses remained on the range after the September sales -- less than 10 percent of the number of animals that can be grazed in years of average forage growth.

The calf crop was surprisingly high considering the severity and duration of the drought. From 275 mother cows on the range as of

January 1, 1953, a total of 249 calves were branded in the year, re pre-senting a 90.5-percent calf crop. This is attributed to conditioning of the breeding herd by supplemental feeding.

Forage production at the Santa Rita Experimental Ran~ was the poorest since_l948 and necessitated reducing_§tocking in most range units.-- During the grazing year, October 1952 through September 1953, annual rainfall averaged 3.4 inches below the longtime average. November was the only

relatively wet winter month. The spring months of February through May were near average in precipitation, but because of poor distribution the precipi-tation was largely ineffective. Precipitation, June through September --the critical months for perennial grass growth -- was 35 percent deficient. June and July rainfall was about average over nearly the entire range; but August rainfall was considerably less than half of average, and no rain fell in September.

The July rains started grass growth quite generally over the range, but August rains were low and poorly distributed. As a result, forage production was low. Xe aompensateofor the reduced available forage, cows were culled heavily and yearling heifers, held over as calves in 1952 because of poor markets, were sold. Average calf weights were lower but light calves ordinarily held over were shipped with the bigger calves. Great variations in forage production

chara_£terize semidese!:i...g~!!sland ranges

Forage production by perennial grasses on desert grassland ranges fluctuates greatly with variation in rainfall. Compilation of rainfall and forage records from 1939 to 1953 for three elevational range types on the Santa Rita Experimental Range illustrates the magnitude of these fluctu-ations. The foothill unit extends from 4,000 to 4,500 feet in elevation; the mesa unit from 3,000 to 4,000 feet; and the desert area lies below 3,000 feet.

Average forage production in the best years was 8 times as great as in the poorest year on the foothill unit; 5 times as great in the mesa unit; and 31 times as great in the desert unit (fig. 1).

Years of high and of low rainfall corresponded at the different elevations. However, rainfall did not vary as much as forage production. Summer rainfall at all elevations was within the range of 57 to 153 percent of average.

Grazing intensity affects both range conditions and cattle prod~cti2.!L_~

Intensity-of-grazing studies under way on three range types in Colorado and Wyoming show the effects of different grazing intensities

on forage and cattle production.

Blue grama - buffalograss range, northeast~!:!}_Colorado.-- At the Central Plains Experimental Range, pastures stocked for heavy grazing (60 percent of the grass herbage utilized) were grazed with 58 head of

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1.--Relative forage production and ave~ge summer rainfall at the Santa Rita Experimental Range, 1939 to 1953, inclusive.

yearling heifers per section (640 acres), pastures stocked for moderate

grazing (40 percent of the grass herbage utilized),were grazed with

41 yearling heifers, and those for light grazing (20 percent of the

grass herbage utilized) were grazed with 29 yearling heifers per section.

Cattle weight gains per acre in 1953 under the

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degrees of grazing use

were 8.1 pounds, 16.8 pounds, and 11.9 pounds for heavy, moderate, and

light grazing, respectively. This was the second successive year that

the moderate grazing gave the greatest cattle weight gains per acre.

Table 1.--Cattle weight gain per acre under light, moderate,

and heavy grazing, Central Plains Experimental Range

Year : Heavy grazing : Moderate grazing : Light grazing

: Pounds per acre

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Pounds per acre Pounds_Qer acre

1940 16 16 11 1941 17 14 10 1942 16 14 9 1943 26 18 10 1944 27 18 10 1945 27 17 10 1946 20 17 10 1947 27 17 10 1948 19 16 9 1949 27 19 10 1950 19 17 10 1951 21 17 11 1952 17 21 11 1953 8 17 12

Mountain grassland range in Wyoming.-- The average daily rate of

gain during the 1953 grazing season for steers in the experimental range pastures on the Bighorn National Forest in north-central Wyoming was

2.2, 2.4, and 2.7 pounds in the heavy, medium-, and light-use pastures,

respectively. As seen in table 2, the gains for all 3 grazing intensities

were greater in 1953 than in 1952; also, greatest daily rate of gain during

the 1952 season was made by those steers in the medium-use pastures. For both years the steers in the heavy-use pastures have the lowest daily rate

of gain per animal. However, the heavy-use pastures have given the greatest

gains per acre.

The experimental pastures were first grazed in 1951 with bred

yearling Hereford heifers. The utilization was less than half of that

desired and as a result none of the pastures received heavy use. In

1952 and 1953 yearling Hereford steers were used and the stocking was

increased where necessary so that desired utilization goals were obtained.

A shorter grazing season in 1953 (75 days -- July 2 to September 15)

than in 1952 (90 days -- June 19 to September 17) probably accounts for the

17-percent decline in pounds of gain per acre in the heavily grazed

pas-tures. The decline in gain per acre on the medium-use pastures was 4

per-cent, and there was an increase of 16 percen~ in the light-use pastures.

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Table 2.--Average daily rate of gain and gain per acre

by yearling steers - 1952 and 1953.1/

Bighorn National Forest

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of (Pounds per head) (Pounds) Percent

~use ___ ~: ___ 1952 -~:~ __ 1953 ____ :_ 1952~: __ 1953 _: _1953_is_of_l2~~ Heavy Medium Light 1.8 2.2 2.1 2.2 2.4 2.7 86.0 63.9 21.4 71.6 61.4 24.9 83 96 116

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Annual weights furnished by Wyoming Agricultural Experiment

Station.

This experiment is a cooperative undertaking by the Bighorn

Permittees Association, Wyoming Natural Resource Board, Wyoming Agricu

l-tural Experiment Station, and the Forest Service.

Ponderosa_J&ne-bunchgrass range.-- U.S. D. A. Circular 929

entitled 11_{Effect of Grazing Intensity Upon Vegetation and Cattle Gains on}

Ponderosa Pine-Bunchgrass Ranges of the Front Range of Colorado," issued

in December 1953, summarizes results of grazing

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range units, 2 at each

of 3 intensities, at the Manitou Experimental Forest. Thirty- to 40-percent utilization of the grass and sedge herbage on pine-bunchgrass ranges is recommended as being a grazing intensity that will maintain forage values

and make efficient use of available forage for beef production. To obtain

this utilization, Arizona fescue rF.esi:!:!£.a ar1·zonica) ~hould be grazea to an average height of 5 to 6 jnches by the end of the gr.azing aeason and

mountain muhly (Muhlenbergia montana) to 1i to 2 inches.

Ponderosa_12ine-bunchgrass_ranges grazed_at 3 intensities_show

different_res122nse to increased_preci121tation after_3_~ars of_drought.

--From 1949 to 1952 herbage yields at the Manitou Experimental Forest,

Colorado, have shown a definite downward trend resulting from the continued

drought prevalent in most parts of the Front Range of the Rocky Mountains.

This reduction in yields occurred regardless of the intensity at which the

range had been grazed in previous years (fig. 2). During 1953, however,

3,80 inches of rain fell during July, followed by 3.52 inches in August.

This moisture increased herbage yields. Yields in 1953 on moderately and

heavily grazed areas were higher than in 1949, the last year of near -average rainfall in the area. On lightly grazed areas 1953 yields were about the same as 1949 and on ungrazed areas, yields were 21 percent below the 1949 level.

Arizona fescue and mountain muhly, both desirable forage species,

showed marked decreases in yield during the drought years under all three

intensities of use and under nonuse. Under the better growing conditions in 1953, mountain muhly increased markedly under all intensities, but

Arizona fescue did not. The increase in yield of mountain muhly from

1952 to 1953 amounted to 73 pounds per acre on heavily grazed areas,

311 pounds on moderately grazed areas, 192 pounds on lightly grazed areas, and 84 pounds on ungrazed areas. Arizona fescue begins growth and reaches maturity earlier than mountain muhly. It is probable that the plants were too near maturity when the rains came to make most effective use of the

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Figure 2.-- Precipitation, and h~rb~ge yields of grasses and

sedges under light, moderate, and heavy grazing,

and no grazing. Manitou Experimental Forest.

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During the drought period herbage yield of fringed sagebrush

(Artemisia frigida) increased under all rates of grazing. It was most pronounced on areas heavily grazed. On unused areas, fringed

sagebrush decreased in the first year of drought and then increased. The increase was greatest in 1953. On heavily grazed areas there has also been a steady increase in the number of fringed sagebrush plants.

Blue grama (Bouteloua gracilis) was less affected by the drought than the other grasses. During 1953 it increased somewhat under all

grazing treatments and nonuse, but made the greatest gains on heavily

grazed range. Since the number of plants was not increased, the higher

yield appears to be the result of denser foliage growth per plant. The

midsummer rains also were ideal for stimulating g~owth of blue grama.

Species utilization on ponderos~ine-bunchgrass ranges_varies

with season and intensity of grazing.-- Utilization of individual forage

species on ponderosa pine-bunchgrass ranges varies both with time and with

the intensity of gra~ing. On heavily grazed areas 57 percent of the

utilization on Arizona fescue occurred during the first 48 days of the

117-day grazing period. Grazing was started on June 1. During the remain

-der of the season utilization continued but at a reduced rate. On

moderately grazed areas 64 percent of the total use of Arizona fescue

took place during the first 48 days. During the rest of the period the

rate of use was much reduced. On areas lightly grazed Arizona fescue

was utilized at an almost uniform rate throughout the season.

Mountain muhly, in contrast to Arizona fescue, was grazed most heavily during the latter part of the grazing season. On heavily grazed areas, only 24 percent of the utilization of mountain muhly occurred during the first 48 days of grazing. Fifty-four percent occurred during the

last 41 days of grazing. This same trend with only minor variations

occurred on all areas. The lighter the intensity of grazing the more

pronounced was the utilization during the later period. On moderately

grazed areas 66 percent, and on light-use areas 69 percent, of the use

occurred during the last 41 days.

Use of little bluestem (Andropogon ~pariu~) and the sedges (Carex spp.) followed the same general trend on heavily and moderately

grazed areas as that for Arizona fescue. They were grazed most heavily

during the first 48 days of the season. After that period, the rate of use declined especially on the areas grazed moderately. On lightly

grazed areas little bluestem was grazed most heavily during the middle

of the summer.

In general, utilization of blue grama and fringed sagebrush followed

the same general use pattern as that for mountain muhly. However, they were both relatively unpalatable as shown by the comparatively light utilization they received even on heavily grazed areas. Also there was

less consistency in the way they were utilized under different grazing intensities. For instance, blue grama on light-use areas received almost

all of its utilization during the middle of the summer. On heavily grazed

areas it was most heavily grazed during the last of the period.

Seasonal palatability and availability appeared to be important

palatability was important in determining when an individual species receives its heaviest use. Arizona fescue, little bluestem, and the sedges appeared to be most palatable during,·the early summer. Arizona fescue, especially, begins growth earlier than mountain muhly and the leaves begin to get tough as soon as seedstalks are formed. Mountain muhly which received its heaviest use during late season begins growth later and even after maturity the foliage remains soft.

Another factor that was important in utilization of forage was the availability of the different species. The heavier use of blue grama and fringed sagebrush on heavily grazed areas occurred where there was a shortage of available forage from the more palatable species of

bunch-grasses. Cattle were forced to utilize more grama and fringed sagebrush.

On heavily grazed areas the plants that were most palatable in early summer continued to be utilized at a heavier rate in late summer than the same species on more moderately grazed areas. Lightly grazed areas appear to give the truest picture of palatability because there is sufficient herbage of all species available. On this basis, fringed sagebrush has little or no palatability; blue grama is only slightly palatable; but mountain muhly, Arizona fescue, little bluestem, and sedges are highly palatable plants.

Estimating_the utilization of_Idaho fescue

Idaho fescue (Festuca ideh2~nsis) is one of the most important forage species on the cattle ranges of the Bighorn National Forest in Wyoming. It accounts for about 50 percent of the grass and grasslike herbage produc-tion on many of the cattle ranges on that forest. In addition, livestock show a high preference for fescue compared to other grasses and sedges. These factors make Idaho fescue a key species on cattle ranges. The degree to which a species is grazed over a period of years is often a valuable indicator of what might be the future of the species as a forage plant on the range. When the species is a particularly important forage plant as is Idaho fescue on these ranges, then the trend of the range as a whole may in a large measure be reflected in the trend of this one species. To aid in judging utilization of Idaho fescue on large areas, a method of estimating percent utilization from the percent of plants grazed was devised. Percent utilization by weight is estimated directly from a chart, using percent of plants grazed, determined from counts along a

paced transect. The curve on the chart (equation Log Y = 0.5668 + 0.01421 X,

where Y is percent utilization and X the percent of plants grazed) shows the relationship between number of plants grazed and percent utilization.

The method has proved to be quick, easy to use, and reasonably reliable. Details of the method are discussed in Station Paper No. 12.

Application of commercial fertilizer to native short-grass ranges_increased herbage producti9n

Field-plot trials of commercial fertilizer application to native

short-grass ranges were made again in 1953 at the Central Plains

Experi-mental Range. Commercial fertilizers were drilled into the soil. The drill penetrated the native sod to a depth of approximately 3 inches.

Six treatments were applied. These were nitrogen alone; phos

-phorus alone; potassium alone; nitrogen and phosphorus together; and

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nitrogen, phosphorus, and potassium together. The rate of application

for each of the elements was:

Nitrogen Phosphorus Potassium

80 pounds per acre 100 pounds per acre 200 pounds per acre

The above applications are heavy, but were made with the objective of

learning whether or not the native vegetation would respond to fertilizer

treatments. The drill was run through the sod on the check plots just

the same as it was through the treated plots to give a measure of effects

of the mechanical treatments on the sod.

The yields of air-dry herbage from the forage grasses for the six

treatments expressed in pounds per acre were as follows:

Treatment Pounds air-drY._12er acre

Nitrogen alone

632

Nitrogen and phosphorus

666

Nitrogen, phosphorus, and potassium 707

Phosphorus alone

565

Potassium alone

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Drilled check plots 468

Native sod -- not drilled

635

Similar comparisons where the fertilizers were applied as top dressing

were established in 1952. These gave no observable carry-over effects.

Deferring grazing on semidesert grassland range

during the growing season benefits desirable grasses

In 1937 a large range unit at the Santa Rita Experimental Range was

divided into two smaller units having similar vegetation and growth

potentials. One unit was subsequently grazed yearlong, whereas the other

was not grazed during the summer growing season but was grazed during the

remainder of the year. Rates of stocking and utilization were about the

same for the two units. Randomly located line transects were measured in

both units in 1941 and in

1953.

The density and composition of tall grasses such as cottontop

(Trichachne californica), poverty threeawn (Aristida divaricata) and

black grama (Bouteloua eriopoda) essentially were similar in 1941 in

both units. Short-grasses in the seasonally used range unit comprised

about twice as much ground cover as the unit grazed yearlong. Rothrock

grama (Bouteloua rothrocki) made up over two-thirds of the total

short-grass ground cover in the deferred unit and comprised more of the ground

cover than all of the other short-grass species in the yearlong unit.

In 1953, after 15 years of grazing treatment, the tall grasses

made up only one-third as much ground cover as in 1941 in the unit

grazed yearlong, while in the deferred unit they made up two-thirds

as much cover as in 1941. Average density of tall grass in the deferred

In 1953 the short-grasses in both range units averaged about

one-third of their 1941 values. The 1953 density of Rothrock grama

was about one-tenth that in 1941 in both units. Santa Rita threeawn

dropped to about one-third in the seasonally protected pasture and to

only four-fifths in the unit used continuously. Sprucetop grama

(Bouteloua chondrosioides), a leading species in 1941, had practically

disappeared by 1953,

Shrubby species in general suffered losses similar to those of

perennial grasses. They decreased to 45 percent of original on the

unit grazed yearlong and to 63 percent on the deferred unit . Burroweed

(Aplopaplli:!S tenuisectus), the most abundant shrub in both units, lost

about half of its original density. Cactus was an exception, increasing

in both units. The deferred unit showed the larger gain. Two desirable

browse specie~, false mesquite (Calliandra sp.) and shvubby E~iogonums

(Eriogonum spp. ) also increased in the deferred unit. Shrubby plants

were not considered a dominant factor in the decline in grass abundance

in either unit.

Changes noted in vegetation lead to the following conclusions:

Not grazing during the growing season benefits tall or desirable grasses.

Drought can be devastating to all life-form groups of vegetation regard

-less of the system of grazing followed. The decline in ground cover of

perennial grass despite nonuse during the growing season and conservative

use emphasizes the difficulty involved in adequately coping with drought.

However, the maintenance of black grama contrasted with the virtual

disappearance of Rothrock grama illustrates the relative worth of

individual species as forage plants in a droughty country. Desert

grassland ranges should be managed to maintain species such as black

grama which can endure drought. Nonuse during the growing season is

one way to maintain the desirable species.

Utilization of tobosa grass can be

iD£r~2sed by spraying with molasses

Molasses in a water solution sprayed on tobosa grass (Hi1~ria mutic_{2 )}

shows promise of increasing the utilization of tobosa forage. Usually

tobosa occurs in rather dense stands, but is readily grazed only during

its period of summer growth; herbage which remains after growth ceases

becomes coarse and hampers grazing the following year. Often it is

difficult to get a reasonable use of it.

Preliminary findings from spray tests on the Jornada Experimental

Range and a cooperative study with the Bureau of Land Management on

A. D. Brownfield's ranch near Deming, New Mexico, have provided helpful

guides for future tests in getting cattle to graze tobosa as an emergency

forage. Solutions which contain 50-percent molasses by volume sprayed

on cured tobosa stands sweeten the tobosa sufficiently to cause the

cattle to consistently return to the sprayed area. Solutions containing

less than 50-percent molasses were initially attractive to the c~ttle

but failed to attract the animals more than a day or two. Furthermore,

it was observed that cattle exhibit little preference for molasses

-sprayed tobosa if there is green tobosa at hand.

- 10

,

,

.

Experience from these tests indicates the following:

1. Areas selected for spraying should have a sufficiently dense uniform stand of grass that only a minimum amount of solution is lost on the ground. Locations close to water and relatively free from dust

and sand which may settle on the sprayed material are also important

con.iderations.

2. Only an area large enough to carry the cattle for a few days should be sprayed at a time. Spraying small areas provides the animals

with a fresh source of molasses-sprayed herbage and reduces the time and

cost lost if dust or rain should annul the spray application.

3. Cattle should be moved to the sprayed area immediately after

spraying and it may be necessary to hold the animals on the area until

they acquire a taste for the molasses.

4. Essential spray apparatus consists of a !Ill.Xlng barrel or tank,

a pump which will handle the somewhat viscous 50-percent solution, and a

boom or nozzle arrangement that will spray uniformly. Grazing requirements of different classes of livestock at_the Central Plains Experimental R a n g e

-A 640-acre short-grass range was grazed by four different classes

of range cattle during the period 1939 to 1953, inclusive. Approximately

the same degree of utilization was obtained each year. The class of livestock, average entrance and leaving weights, and number of months

of grazing obtained are as follows:

:Number of: Average Class of cattle : seasons : entrance

______________ :_grazed : __ weight

Cows with calf 3 summers

Yearling steers 4 summers

Dry cow~!/ 2 winter..s

2-yr-old heifers 5 summers

Lb§.:.._~r.J:!~~£ 98l(combined) 498

?/1,000 640

Average :Average unit

leaving :months grazed

weight _ per vear

Lb§~~.!:_head No. l,421(combined) 710

2/

863 144 227 181 201

1/

Grazed in November, December, and January, supplementing during

January with approximately 0.75 pound of cottonseed cake per head per day.

Y

Estimated only. No removing weights.

RANGE RESEEDING

Reseeding ponderosa pine range

in_Arizona ~nd_New Mexico _ _

Reseeding can be used to restore many deteriorated openings in the

ponderosa pin~ zone of Arizona and New Mexico to high forage productivity.

It can also provide for a quick protective cover on timberlands disturbed

reseeding for these purposes has been brought together and is being

processed for release as a U. S. Department of Agriculture publication. Twenty-three species, varieties. and strains of over 170 tested were found to be adapted for reseeding openings. Each has characteristics which fit it for a particular use. Seedbed preparation is usually

necessary to remove competing vegetation and prepare the soil. Plowing 3 to 4 inches deep with a disk-type plow is generally recommended.

Drilling with a single-disk grain drill is the best planting method

wherever it can be used. Optimum planting depths vary from

t

to 1 inch. Summer planting between June 15 and August 15 has been most consistently

successful. At higher elevations planting can be continued into the fall.

Management practices for establishment and maintenance of reseeded stands include: (1) Integrating reseeding and other range improvements;

(2) selecting species with growth characteristics and palatability which

will aid in balancing seasonal forage needs; (3) protecting new plantings from grazing for the first two growing seasons;

(4)

utilizing no more

than 50 percent of total herbage production each year after that;

(5) basing livestock numbers on each year's forage supply; (6) encouraging

even utilization by fencing, water development, salting, and riding; and

(7) light grazing during drought.

Recent burns and areas denuded by logging offer excellent sites for reseeding, and some of the old burns can be satisfactorily reseeded.

Nineteen species and varieties found adapted to such areas afford a good choice and provide various combinations of longevity, soil protection,

seedling vigor, palatability, ability to withstand grazing, seed resistance

to washing, and competition to ponderosa pine regeneration. Seed can be

broadcast in the loose ash of recent burns and on logged areas where the

soil surface has been loosened during timber harvest with good results.

Where the soil surface has been compacted by soil settling, washing,

or use of heavy equipment, cultural treatment is necessary. The best

time for reseeding pine burns is just before the first hard summer rains, approximately June 15 to July 1. On disturbed timberlands seeding

should be done at the time when soil is loose and when adequate

precipi-tation for establishment can be expected. Reseeded stands on disturbed

pine timberlands should be given protection from grazing the first year and conservatively grazed thereafter.

Promising species for range reseeding

in the woodland zone in Arizona ~ - - ---

--Dryland row plantings 2 to

8

years old at

6

locations supplemented

by numerous larger plot and pilot plantings were analyzed to determine which show promise as suitable for artificial reseeding in the woodland

zone in Arizona (table

3).

For this purpose the woodland zone was divided

into five combinations of elevation, moisture, and temperature as follows: 1. Cold, dry woodland above 6,000-feet elevation with an average

annual precipitation of 12 to 15 inches. Snow occurs during most of the winter and below-zero temperatures are common.

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"

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Table 3.--Promising species for reseeding in the

woodland zone of Arizona

Relative success!l

S p e c i e s Cold : Cold : Coo::. : Cool ':'Warm dry :moist: dry :moist:moist Cool-weather growers

Chamiza (Atriplex canescens) G

Wheatgrass, bluestem (Agropyron smithi) G Wheatgrass, crested (A. cristatum) G Wheatgrass, desert (A. desertorum P Wheatgrass, intermediate (A. intermedium) P

Wheatgrass, Siberian (A. sibiricum) G Wheatgrass, stiffhair

(A

.

tricophorum) P

Wheatgrass, tall

(A

.

elongatum) VP Wildrye, Russian (Elymus junceus) F

Warm-weather growers

Bluestem, Caucasian (Andropogon

intermedius Caucasius) 0

Bluestem, Turkestan

(A

.

ischaemum) VP

Curlymesquite (Hilaria belangeri) 0

Fingergras~, wo0l]y· (Qigitaria eriantha) 0 Galleta (Hilaria jamesi) 0 Grama, black (Bouteloua eriopoda) 0

Grama, blue (B. gracilis) VP Grama, sideoats (B. curtipendula) 0

Lovegrass, Boer (Eragrostis chloromelas) 0

Lovegrass, Kimberly (E. brizantha) 0 Lovegrass, Lehmann (E. lehmanniana)

Lovegrass, weeping (E. curvula) 0

Muhly, spike (Muhlenbergia wrighti) P Panicum, Halls (Panicum halli) 0

Triodia, rough (Triodia elongata) 0

Triodia, white (T. albescens) 0

Windmillgrass, hooded (Chloris cucullata)

-Wolftail (Lycurus phleoides) 0

G E G G G G E G E 0 F 0 p p 0 p F p 0 0 G p 0 0 G F F VP VP VP F p F VP VP 0

"

O

VP VP F G 0 0 0 0 VP F F VP 0 Q •. p E F p G VP G G p E E G E G G G E E G E E F G G G G

17

Relative success: E

p excellent; G _{poor; VP= very poor;} = good; F ₀ = ₌ fa_failureir; _.

'?:./

-

= Not tested _'?:) 0 0 0 0 0 0 0 G F 8 0 p G E F E p 0 F F F 0

2. Cold, moist woodland with elevations and temperatures similar to the cold, dry woodland but with an average annual precipitation of 15 to

18 inches.

3. Cool, dry woodland between 4,000 and 6,000 feet elevations and with an annual precipitation less than 16 inches. Snow occurs at the higher

elevations and temperatures below zero are uncommon •

4

.

Cool, moist woodland with the same elevations and temperatures as the cool, dry woodland but with the average annual precipitation above

5, Warm, moist woodland at elevations from 4,000 to 5,500 feet and with an average annual precipitation above

17

inches. Snow periods are short

and infrequent and temperatures rarely drop below zero.

These conditions overlap widely due to the effects of exposure and are therefore only approximate delineations.

At the higher elevations with relatively low temperatures, the best adapted species are predominantly cool-season growers. With decrease in elevation and the resultant increase of temperature, the warm-weather growers tend to be more adapted, and at the warmest tested site only warm-weather

growers have been able to survive.

Reseeding desert grassland ranges in southern Arizona

Arizona Agricultural Experiment Station Bulletin No.

24

9

,

"Reseeding Desert Grassland Ranges in Southern Arizona," was published in July

19

5

3

cooperatively with the Arizona Agricultural Experiment Station and the Soil Conservation Service. This bulletin summarizes available information on how to reseed the arid desert grassland ranges.

The sites for reseeding are those with deep, fertile,

medium-textured soils, above 4,000 feet in elevation, and that receive 14 inches or more rainfall annually. On these sites Lehmann lovegrass (Eragrostis le!lmannt~!le.) and Boer lovegrass (!h_ chloromelas) are the best species to use. Cottontop, black grama, and blue grama can also be used but are more difficult to establish. Weeping lovegrass (!h_ curvula) and sideoats

grama (Bo~te1~ curtipendula) are suitable for the more moist sites.

Wilman lovegrass (!h_ superba) can be used where temperatures do not fall

below 100F.

On upland areas receiving less than 14 inches of rainfall, Lehmann lovegrass is the only species that can be generally recommended. Boer

lovegrass can be used on the more moist sites and Wilman lovegrass in warm locations. At the present time no reseeding is recommended where average annual rainfall is less than

11

inches.

Reseeding should be done in May or June just prior t o the summer rains. Pitting to conserve moisture, followed by cultipacker-seeding, has been the most consistently successful method. Ripping and contour furrowing have given good results on fine-textured bottom-land soils.

Rotary tiller tested in southwestern chaparral type

A test to determine the suitability of a rotary tiller for brush

eradication and seedbed preparation in the chaparral type was made in June

1953

,

2

5

miles north of Globe, Arizona.

The tiller consists of a rapidly rotating drum

(

1

75

r.p.m. ) on whichare· mounted many metal tines. The drum can be raised or lowered so that the tines operate above the ~round surface or as deep as

12

inches in the soil. The rear hood can be adjusted to incorporate the chopped

plant material in the soil or to spread it over the surface of the soil.

- 14

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.

•

Vegetation on the plot consisted largely of shrub live oak with

some squawbush (Rhus t.rilobat.;:i.), algerita (Berberis sp.), and catclaw (Ac~cia sp.). The drum was set to operate at a soil depth of about 4 inches. A very loose, pulverized seedbed in the coarse granitic soil

covered with a mulch of shredded brush was obtained, and practically no live stems were visible.

In sparse stands of shrubs the tiller tended to leave an uneven

and spotty mulch. Three months after treatment ground covering was

32-percent mulch, 4-percent live vegetation. Sixty-four percent of

the soil surface was bare.

The most serious limitation of the tiller was that the roots of

sprouting shrubs were not sufficiently disturbed to prevent sprouting when the tines are operating at a 4-inch soil depth. Although the tiller destroyed the above-ground parts of the plants, sprouts developed from

57 percent of the original shrubs. Operating at greater depths greatly

increases the danger of damage to the machine from striking rocks.

On the basis of this test, this model does not seem practical for

large-scale mechanical control of chaparral.

Livestock gains on crested wheatgrass average_2.5 times_those on ad1acent ranges

For the second successive spring, cattle weight gains were unusually

high on the crested wheatgrass ranges on Cebolla Mesa, north of Taos,

New Mexico. The average rate gain of 3.3 pounds per day in 1953 for all

animals on the crested wheatgrass areas was only slightly below the 3.6 pounds per day average in 1952. These unusually high gains were

due to the thin condition of animals when they were placed on the reseeded range and reflect the quality of crested wheatgrass forage in contrast to

that on adjacent pinyon-juniper rangeland. Cattle of similar quality

and condition held on the adjacent native range in poor condition gained

on the average only 1.3 pounds per day.

Weight gains by animal classes and grazing intensity for both 1952

and 1953 are listed in the following table:

: Degree : __ Average dai1z_weight gains .Ll:bs. ~ ! : . _ ~

Cover type : ot' :C :₈ .f : Cows and :C :C

1 : Cows and . ows ei ers . ows aves

--- : grazing : __ : __ : heifers : _ : _ _ _ : calves

Crested wheatgrass Crested wheatgrass Crested wheatgrass Native range Heavy Moderate Light Heavy

3.8

4.0

5

.

0

2.7 2.6 3.4

3

.

3

3.4 4.2 2.9

4.4

4.

5

1.6

2.8 2.5 2.8 1.0 2.9 3.4 3.6 1.3

Weight gains in 1953 corroborate those obtained in 1952. Animals

on the lightly grazed crested wheatgrass range gained most rapidly and

Herbage utilization for this study during the past 2 years is shown in the following table:

Pas-: : Planned: Actual percent utilization

ture : Cover degree Grass herbage _Pingu~

___ : ____________ : of use : 1952 : __ 1953 __ ]_95} __

:

1 Crested wheatgrass Heavy 76 62

2 Crested wheatgrass Moderate 61 44

3 Crested wheatgrass Light 55 23

4 Native range Moderate

--

66 74

---In 1953 the same number of cattle grazed the 33-acre heavily used crested wheatgrass range as the approximately 400-acre adjacent native sagebrush - pinyon juniper range. The inadequate and poor-quality herbage on the native range forced cattle to graze the noxious half-shrub pingue (Actig~ richards£ni). This may account for the small weight gains.

Response of creGted wheatgrass to varying intensities of utiliza-tion in the spring is beginning to show a definite trend after only

2 seasons of differential use. The herbage production given as ratios of the heavily used pasture is:

Deg_!:~~ of u~

M~squit~

Heavy Moderate Light

Prior to grazing experiment 1.00

1.11

1.48

NOXIOUS PLANT CONTROL

1952 1.00 1.12 1.72 1953 1.00 1.24 1.84

Abs2rption and translocation of herbicides in mesquite seedling§ are increased by addition of nont2xic oil.-- A nontoxic oil-water

emulsion proved to be superior to diesel oil as a carrier for 2,4,5-T as demonstrated by markedly greater absorption and translocation of this herbicide by mesquite seedlings growing in the greenhouse. A nontoxic oil was also tested in a 20-percent oil-water emulsion with various wetting agents, and different formulations of 2,4,5-T. Optimum t rans-location from four centrally located leaves of mesquite seedlings treated with 2,500 p.p.m. of herbicide occurred with the more water-soluble

formulations. The sodium and triethylamine salts moved into nontreated portions of the plants to a much greater extent than did esters.

Colloidally ground acid of 2,4-D and an emulsifiable acid of 2,4,5-T gave relatively poor results when carried in a 20-percent nontoxic oil-water emulsion. Granules of 2,4,5-T acid and the butoxy-ethanol ester of 2,4-D were somewhat more effective.

Differences in activity were noted among some 30 wetting agents applied at concentrations of 0,3 to 2.0 percent in conjunction with 2,500 p.p.m. of the triethylamine salt of 2,4,5-T in a 20-percent

- 16

•

•

•

nontoxic oil-water emulsion. Wetting agents giving maximum trans

-location from the treated leaves to both the apical and basal portions of the plant were as follows:

Armour Chemical

Colloidal Products

Emulsol Corporation

Monsanto Chemical

Ninol Laboratories Nopco Chemical Company

Shell Oil Company

Wyandotte Chemical Company

Ethomid HT/15 Multifilm L, L-SX, 402·,- 403 Emcol H-77 Emulsifier H Toximul 400 Agrimul 11 Weedkiller emulsifier Pluronic L-44

The effect of different treatments on trans!ocation of he£2icide

l!!_m~sgu!~~·-- Absorption and translocation of externally applied

carbohydrates are known to be greatest when a plant has been starved of its natural metabolites by pre-dark treatment. To investigate the relation between carbohydrate translocation, one group of plants was given normal light and another group treated with a 27-hour dark period.

These groups were then treated with either the sodium salt or the propylene-glycol-butyl-ether ester of 2,4,5-T at 4,000 p.p.m. acid equivalent, in connection with one of the following: (1) 4-percent glucose; (2) molasses extracted from ponderosa pine diluted to

4-percent carbohydrate content and acidified; (3) 4-percent emulsion of Goodrite Latex VL-600 (Goodrich Chemical Company); (4) no additives

(control). In the oase of the sodium salt, pre-dark treatment resulted

in less damage than when plants were left in the light. Pre-darkness treatment had no effect upon the results of applying the ester. With time, all significant differences between dark and light pretreatments and different additives disappeared among the treated leaves.

Two days after application, leaves treated with the ester were

considerably more damaged than those treated with the sodium salt . The sodium salt was absorbed and translocated far more readily than the ester as evidenced by severe formative effect to the apex and young leaves, as well as to the older leaves. A smaller number of sprouts appeared at and above the nodes of leaves treated with sodium salt than with the ester.

Ca~~Qhydrate translocaiion !!:!_ll}esquite under investigation

.--A study relating herbicidal response to the developmental stage of the mesquite tree and to the carbohydrate content of various tissues at different periods throughout the year was initiated in 1953.

Costs of two methods of applying diesel oil_to velvet mesquite

£Ompar~£·-- Diesel oil sprayed or poured around the base of the tree form of velvet mesquite is an effective control measure but is sometimes

too costly. In seeking a method of reducing the cost, use of an

orchard hand-carried pressure spray can was tested against application with a pressure rig mounted on a pickup. Total cost of treating mesquite

by the two methods is practically the same -- $0.042 a tree for the

hand-carried spray can and $0.045 per tree for the pickup-mounted rig

Pickup-mounted

Hand-carried pressure

Item~ spray can oi+ing rig

Total number trees Trees per acre

Man-hours for treating

Labor cost per tree (labor at

Diesel oil cost per tree (oil

Total cost per tree

$1 per hour)

at 14.7i per gal.)

257 75 3-2/3 $0.014 0.028

-$0.042 506 71 12 $0.024 $0.021 $0.045

The cost for oil was less with the pickup-mounted rig because slightly

less diesel oil per tree was inadvertently used. This resulted in a kill

of 86 percent of the plants treated, compared with a 98-percent kill

with the hand-carried can. Labor costs were higher for the pickup-mounted

rig. Either method can be used to kill velvet mesquite at a relatively

low cost.

Fortified diesel oil_§:£.Plied as a basal~ay for killing velvet

mesquite compared with basal application of diesel oil alone.~ Fortifying

diesel oil with 2,4-D and 2,4,5-T or other herbicides to increase the

percent kill has been advanced as a promising technique. The following

table compares basal-spray applications of straight diesel oil and three

fortifying agents that have given the best plant kills.

Treatment

Diesel oil alone

2,4,5-T acid equivalent in diesel oil.Y 1% solution 2. 5% solution 5% solution 10% ~elution 2,4-D and 2,4,5-T in diesel oil17 1% solution 5% solution Ethylene dibf9mide in diesel oil!il

No. of treesI/ treated

per gallon of solution

: 32 16 :

_;_it;

pt. per tree):

Cl

pt. per tree): % Plant kill : .

%

plant kill

15.7 45.0 37.5 67.5 40.0 50.0 62.5 67.5 25.0 95.0 60.0 95.0 80.0 65.0 1% solution 30.0 80.0 70.0 30.0 3% solution 40.0 5% solution 50.0 Approximate cost per gallon of solution $0.149 0.389 0.772 1.395 2.641 0.348 1.142 0.210 0.332 0.454

-

--

-

Y

Trees of about 3-6 inch_g_r_o_un_d __ d_i_am_e-te-·r-w_i_t_h_n_o_t_m_or_e_ t_h_a_n _ _ three stems emerging from the ground.

'?:./

2,4,5-T ester 4 lb./gal. at $14.20 per gallon.

l/

2,4,5-T and 2,4-D esters at

4

lb./gal. and $11.32 per gallon. ~/ Ethylene dibromide: 85% at $6.06 per gallon.

- 18

-'

,

II.

'"

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..

The one-fourth pint of material in either fortified or straight

diesel oil did not result in acceptable kills except in the case of the

5-percent solution of the 2,4-D and 2,4,5-T mix. The one-half pint-per

-tree rate gave acceptable kills with 10-percent 2,4,5-T; 1-percent 2,4-D and 2,4,5-T; and 1-percent ethylene dibromide. The cost per

gallon of a 10-percent solution of 2,4,5-T makes its use impractical.

The results of treatment with 1-percent ethylene dibromide and 1-percent

2,4-D and 2,4,5-T mix in one-half pint per tree of diesel oil suggest

further work is desirable. The cost per tree with these compares favo

r-ably with the use of 1 pint of straight diesel oil per tree. Use of

1 pint per tree of straight diesel oil is the most economical and

practical except for the 1-percent ethylene dibromide in one-half pint

of diesel oil per tree.

No differences in kill of velvet mesg~ite noted among five esters 2£_~i4.5-T.-- Five esters of 2,4,5-T were applied by airplane in the

spring of 1952 on 5-acre plots of velvet mesquite at the optimum growth

stage for effective spraying. Five gallons per acre of a spray mix of

three-fourths pound per acid equivalent in 1:4 diesel oil-water emulsion

was sprayed on 42-foot flight strips. There was no appreciable diffe

r-ence in plant kill or top kill of mesquite among the five esters as

indicated below:

Plant kill Top kill

Ester

Butoxy ethanol

Propylene glycol butyl ether esters

Isopropyl and amyl esters

Pentyl esters

Polyethylene glycol ester

Percent Percent

---

----20 24 26 24 26 76 62 60 84 87

Phenology of velvet mesquite as an index to proper spraying_time

.--In a 5-year period at the same site, leaf buds and flower buds of velvet

mesquite have burst as early as March 28 and as late as April 24. Leaves

have remained in the succulent but full-leaf stage for periods of 10 to

56 days and have hardened off into mature leaves as early as May 2 and

as late as June 22. Pods have appeared on the flowers from 24 to 76 days

after flowering started. The time pods reached maturity varied from

June 17 to August 24.

Often the early spring flowers abort before pollination due to lack of soil moisture or are destroyed by wind or rain. When this occurs,

a new reproductive cycle is started when growing conditions become favor

-able. Flowers and pods in various stages of growth may occur on a single

tree at any time from April through September. As many as 3 distinct

flowering cycles have been noted on an individual tree in 1 growing

season. Differences of 1,000-feet elevation have caused variations of 10 days in the time of flowering and leafing •

Frequent-interval spraying tests run in con~unction with phenological observations have indicated that the optimum time for spraying velvet

mesquite may be recognized when full succulent leaves appear, the flowers

are mature, and pods less than 1 inch long are beginning to form. At

one elevation on the Santa Rita, optimum conditions did not occur on the

only 9 days in 1950, 11 days in 1952, and 18 days in 1953. From these

phenological observations it then seems that some years may not be

suitable for extensive spraying of velvet mesquite; and even in years

when the external characteristics indicate possibly successful spraying,

the period of optimum conditions may be extremely short.

Relation of leaf moisture

to kill of hon~_@esg!:!,;l:te

As a criterion f.or determining the optimum time for maximum

effectiveness of herbicides applied to honey mesquite, investigations

of leaf moisture and weekly foliage spray treatments were continued at the Jornada Experimental Range in a cooperative study with the New

Mexico Agricultural Experiment Station. A concentration of 1,000 p.p.m.

of 2,4,5-T PGBE ester in water was used in all tests since the effect of

season is more easily discernible at this concentration, which represents

about the threshold level of toxicity of honey mesquite to 2,4,5-T.

Evaluation of tests conducted in 1952 indicates that the highest

complete kill -- 65 percent -- resulted from the June 9 treatment. At

this time the leaves were only recently matured and the pods were from

4 to 8 inches long. The pattern for leaf moisture showed a steady decrease

from 73.17 percent when leaves began to emerge on May 1, to 55.08 percent

on June 9. During subsequent phenological development the leaf moisture

declined to approximately 49 percent before increasing slightly as a

result of new growth after the summer rains began. Leaf moisture rose

to 54.51 percent with a corresponding increase in plant kill to

46 percent during this period.

Initial leaf development began Aprill? in 1953 contrasted to

May 1 in 1952. Growth was slower, however, and phenological development

was at the same stage in both years by mid-May after which the growth

cycle continued in the same pattern and time sequence for both years.

Leaf moisture and plant development were approximately the same on

June' 9 in the 2-year period.

Correlation analysis of the 2-year data indicates a highly

significant association between leaf moisture and susceptibility of

mesquite to 2,4,5-T.

Invasion of_grasslands_bv me~uite

In April 1935 a belt transect was established on the Jornada

Experimental Range to measure changes in the extent and succession of

black grama and adjacent mesquite sand dunes. Running from east to

west, the transect is 1,500 feet long by 1 foot wide. The first 500 feet

of the transect was originally within the mesquite-dune type and

con-tained about 70 percent of the total mesquite plants; the next 500 feet

lay across the intermediate zone; and the last section in grassland where

black grama was dominant. Iron stakes at 50-foot intervals along the

transect were notched for measurement of the soil level.

Recharted in July 1950, 15 years later, the transect indicates

that the vegetation is changing from black grama to a mesquite-sandhill

type. Chan~es in the size and numbers of the mesquite plants and

- 20

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.

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~

.

..

movement westward of the dune area are shown in the following table:

Changes in vegetation along the 1,500-foot transect

- - - in number of._Elants and in number of_feet

-1935 : _ _ _ _.12..5.Q Change Change

Vegetation: No. : No. feet : No. : No. feet : of in feet

--- :_12lants: occupied _;__plants : occupied : _ _plants occupied

Mesquite 16 98 Snakeweed 81 60 Black grama

_--

696 Drop seed

--

85 Yucca 9 7 Changes in the soil Number of dunes Height of dunes

Erosion, sand dune area

Erosion,!7 black grama area

36 55 14 171 56 533 41 13 surface along 1935 7 1.23 feet Percent Percent +125.0 - 32.1 + 55.5 the transect +74. 5 - 6.7 -23.4 -51.8 1950 12 1.45 1.77 0.85 +85.7 feet inches inch

Jj 83 percent of iron stakes show erosion in 1953.

At the time the transect was laid out the nearest water was nearly

4 miles distant. A year later, in 1936, water was developed at a distance

of 1 mile from the transect. Grazing has been deferred during the growing

season to protect the black grama, and stocking of the area has been

moderate, averaging a third lighter than the intensity that is usually

considered proper for black grama.

Tarh!J§.h

Promising control measures for tarbush.-- In New Mexico, heavy

stands of tarbush (Flourensia cernua) have become established on areas

that were once dominated by grass vegetation. The number of tarbush

plants was reduced 73 percent by railing. Crown cover of tarbush on

railed plots was 1.58 percent in contrast to 27.65 percent on adjacent

unrailed plots.

Railing treatment consisted of pulling an 8-foot section of rail

weighing 240 pounds over the area. Towing the rail behind a pickup

traveling at approximately 10 miles per hour, it was necessary to drag

the area only in one direction.

Evaluation of several chemical treatments on tarbush was made on

plots treated in 1952. The highest kill in a series of tests was 87.5 per

-cent obtained with an August application of one-half pound per acre acid

equivalent of 2,4-D in a 1:4 oil-water emulsion. Treatments in May 1952

gave a kill of 37 percent using one-half pound per acre acid equivalent