Effect of Cattle Grazing, Seeded Grass, and

an Herbicide on Ponderosa Pine Seedling

Survival and Growth

Philip M. McDonald Gary O. Fiddler

United States

Department

of Agriculture

Forest Service

Pacific Southwest

Research Station

Research Paper

PSW-RP-242

http://www.psw.fs.fed.us/
Publisher:

Albany, California

Mailing address:

PO Box 245, Berkeley CA

94701-0245

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http://www.psw.fs.fed.us

Pacific Southwest Research Station

Forest Service

U.S. Department of Agriculture

Abstract

McDonald, Philip M.; Fiddler, Gary O. 1999. Effect of cattle grazing, seeded

grass, and an herbicide on ponderosa pine seedling survival and growth.

Res. Paper PSW-RP-242. Albany, CA: Pacific Southwest Research Station,

Forest Service, U.S. Department of Agriculture; 15 p.

On a site of above-average quality in northern California, an early

shrub-forb-grass plant community was treated by artificially seeding two forage

grass species at plantation age 3, cattle grazing with and without seeded grasses,

and applying a soil-active chemical (Velpar). Planted ponderosa pines were part

of this community. Results for a 10-year period (1988-1997) are presented for

planted pines, manzanita, other shrubs, forbs, and grasses (natural and seeded).

In general, the pines, manzanita, and grasses were numerous and developing

well after 10 years, and the other shrubs and forbs were declining in density or

foliar cover or both. Velpar was the only treatment that significantly improved

pine seedling growth. Grazing did not. The seeded (introduced) grasses, which

were heavily grazed, probably reduced damage to the pines. The grasses also

helped reduce manzanita foliar cover when grazed. No evidence was found that

the introduced grasses served as a biological control in terms of reducing the

density of manzanita or other shrubs.

Retrieval Terms: cattle grazing, northern California, plant community dynamics,

ponderosa pine, seeded grasses, vegetation management

The Authors

Philip M. McDonald and Gary O. Fiddler are Research Forester and Supervisory

Forester, respectively, with the Pacific Southwest Research Station’s Silviculture

Laboratory, 2400 Washington Ave., Redding, CA 96001.

December 1999
Pacific Southwest

Research Station

USDA Forest Service

Research Paper

PSW-RP-242

December 1999

Effect of Cattle Grazing, Seeded Grass, and

an Herbicide on Ponderosa Pine Seedling Survival

and Growth

Philip M. McDonald Gary O. Fiddler

Contents:

In Brief .............................................................................................................................. ii

Introduction .................................................................................................................... 1

Methods............................................................................................................................ 2

Location and Site Characteristics ...................................................................... 2

Study and Design .................................................................................................... 3

Sampling .................................................................................................................... 4

Results............................................................................................................................... 5

Plant Diversity ......................................................................................................... 5

Manzanita .................................................................................................................. 7

Other Shrubs ........................................................................................................... 7

Forbs .......................................................................................................................... 8

Grasses ...................................................................................................................... 9

Ponderosa Pine ....................................................................................................... 9

Discussion and Conclusions........................................................................................ 11

References ....................................................................................................................... 14
USDA Forest Service Res. Paper PSW-RP-242. 1999.

In Brief...

McDonald, Philip M.; Fiddler, Gary O. 1999. Effect of cattle grazing, seeded

grass, and an herbicide on ponderosa pine seedling survival and growth.

Res. Paper PSW-RP-242. Albany, CA: Pacific Southwest Research Station,

Forest Service, U.S. Department of Agriculture; 15 p.

Retrieval Terms: cattle grazing, northern California, plant community dynamics,

ponderosa pine, seeded grasses, vegetation management

Although plantations are established and maintained to ensure that conifer and

hardwood seedlings grow at the potential of the site, some bare ground usually is

present, particularly when the seedlings are small. This bare ground is susceptible

to erosion and is considered by some people to be unsightly. Covering the

ground with plants that have low competition potential in terms of moisture use

would mitigate or solve the problems of erosion and unsightliness. If this

vegetation was palatable and of sufficient quantity, the cattle that it sustains

could serve as another yield from the land and help pay for the cost of establishing

the plantation. Furthermore, if the cattle concentrated on it, it could mean less

damage to the conifer seedlings. And, if this vegetation would inhibit the

germination of shrub seeds in the soil, or seeds of other weeds that were carried

into the area, it would act as a biological control.

The objectives of this 10-year (1988-1997) study were fourfold: (1) to identify

and quantify the vegetation that became present in a young ponderosa pine

plantation in the northern Sierra Nevada of California; (2) to evaluate the

effectiveness of two direct vegetation management treatments—herbicide and

cattle grazing—for reducing the size and number of plants in various categories

of competing vegetation; (3) to evaluate two species of introduced forage grasses

for their ability to rapidly cover the land and grow well, for their potential to

inhibit the density and development of other species of vegetation, and for their

potentially negative effect on the growth of planted ponderosa pine seedlings;

and (4) to quantify the survival and growth of the pine seedlings in these

treatments.

Some of these objectives were achieved, and others were only partially

successful. For the first objective, plant diversity increased from 17 species in fall

1987 to 35 species in 1997, and trends in density, foliar cover, and height were

determined for manzanita, other shrubs, forbs, and grasses over the 10-year

study period. In general, manzanita and grasses (native and introduced)

prospered, and other shrubs and forbs declined. Total number of plants in the

fenced and ungrazed control was 298,400 per acre at the beginning of the study

and 128,750 per acre at the end. For the second objective, the herbicide Velpar

lowered the density and foliar cover of plants in most of the vegetation categories,

although most differences were not statistically significant. The cattle grazed the

grasses heavily but not much else. Overall, cattle grazing was not a significant

treatment for reducing the vegetation that was competing for site resources with

the pine seedlings.

For objective three, the introduced grasses became established quickly,

grew well, and spread to other treatment areas. No evidence was found that

they reduced the density and development of other species or the growth of

ponderosa pine seedlings. They probably did prevent the cows from

damaging the terminal shoots of the pine seedlings. For the fourth objective,

only Velpar significantly increased the average diameter, height, and foliar

cover of the ponderosa pine seedlings relative to most of the other treatments.

None of the other treatments differed significantly among themselves. Thus,

introduced grass, grazing, their combination, and interaction with the pines

did not produce significant results.

ii
USDA Forest Service Res. Paper PSW-RP-242. 1999.

Forest vegetation managers have many techniques to manipulate unwanted

vegetation in young conifer plantations. If the vegetation is palatable, one such

technique is to use cattle. Increasing evidence shows that to be effective, release

must take place when the conifer seedlings are young. However, young seedlings

are vulnerable to consumption and trampling by cattle. In this study, cattle

grazed the area only 3 months after planting—a possibly risky, but sound option

that enhances grazing as a vegetation management technique. In spite of this

effective beginning, grazing by cattle never significantly enhanced the growth of

ponderosa pine seedlings. Although the pines did not benefit, the cattle did, and

the owner was pleased with their performance and probably with the economic

return. Thus, the acceptability of grazing the transitory range in plantations

should be judged on the basis of both the growth of the trees and that of the

animals.

iii
USDA Forest Service Res. Paper PSW-RP-242. 1999.
USDA Forest Service Res. Paper PSW-RP-242. 1999.
PSW-RP-242

Research PaperResearch StationPacific SouthwestForest Serviceof AgricultureDepartmentUnited States

on Ponderosa Pine Seedling Survival and GrowthEffect of Cattle Grazing, Seeded Grass, and an Herbicide
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