Workshop on New Grass Germplasms
31
problems are pronounced in areas that are weed infested, have degraded soils, or
are prone to repeated fires. Another problem for natives is the limited supplies of
seeds, making them more expensive.
Commonly used introduced grasses have been criticized because early seed-
ings were often monocultures, they may displace native species, they reduce bio-
diversity, and they can disrupt the ecology and aesthetics of the plant community.
However, studies have shown that introduced grasses are seldom invasive, can
occur in diverse ecosystems in native habitats, and often co-exist with natives.
Introduced grasses can act as an "ecological bridge" to the establishment
of native grasses. An example of using an ecological bridge is demonstrated in
strategies to reduce cheatgrass infestations. Cheatgrass was accidentally intro-
duced in the late 1800s, and virtually all sagebrush and bunchgrass ranges are
infested with it to some degree today. Cheatgrass is a major threat to ecological
balance, resource conservation, and productivity. It forms a closed system and
fuels recurrent fires, thereby perpetuating cheatgrass dominance. A logical means
of controlling cheatgrass is to replace it with a perennial grass, but there has been
limited success with native grasses being able to replace cheatgrass. The intro-
duced crested and Siberian wheatgrasses have shown potential in inhibiting
cheatgrass growth and may be used as a "bridge" to establish natives. The new
varieties developed on the SERDP research program are particularly promising.
`Vavilov' Siberian crested wheatgrass seeded into a cheatgrass stand is able
to do quite well without the use of herbicides. It may provide a possible "bridge"
to the establishment of perennial native grasses. However, recruitment of natives
from indigenous seed sources into crested wheatgrass seedings can be a slow
process. We recently completed two evaluations of using different methods to
seed native and introduced grasses together.
Bluebunch wheatgrass establishment through Siberian wheatgrass bridge
In the first study, we examined the establishment of the native bluebunch
wheatgrass using a Siberian wheatgrass bridge. The study was seeded at Yakima
Training Center in November 1998. We used four-row plots with 25- or 38-cm
row spacings. The seeding rate was 100 PLS per linear meter. The experiment
used Snake River wheatgrass (native), bluebunch wheatgrass (native), and
Vavilov Siberian wheatgrass (introduced) in the following treatments:
A monoculture of each of the above three grasses
A binary seed mixture of Vavilov with each native grass
Alternating rows of Vavilov with each native grass.
Previous Page
