[APWG] Bothriochloa ischaemum invasiveness question

[Scott Lenharth]

This was the most difficult of the non-native grasses to manage in Texas.
It starts in any area of disturbance, xeric to wet-mesic, and forms
monocultures.  It can be killed with glyphosate, although individual short
rhizomes often survive, and within months will re-dominate from the seed
bank.  It blooms opportunistically with rainfall.  In small amounts it can
be hand-removed, but regardless of treatment only very strong competition
from other grasses will control it.

A clip from an essay with some useful sources, below.  Also see the 2011
Natural Areas Journal article that mentions herbicide tests with this and
several other grasses in Texas.

"Avian behavioral activities are better facilitated by heterogeneous
habitat structure (Wiens 1974).  The dominance of non-native "King Ranch"
bluestem (Bothriochloa ischaemum var. songarica) in grassland and
mixed-shrub communities poses a problem for the preserve.  Bothriochloa
grows densely on all soil types, forming extensive mats that compete for
light and moisture.  Areas where Bothriochloa dominate have significantly
less native perennial herbaceous species (Gabbard and Fowler 2008).  The
availability of food, in the form of arthropods, is attributed to grassland
forb cover.  The poor forb cover in a Bothriochloa-dominated grassland thus
results in a much lower avian richness (Hickman and others 2006).  Since
the nesting success of grassland birds is positively impacted by diverse
structure (Winter and Faaborg 1999), the observed monoculture of
Bothriochloa further affects native grassland birds."

Gabbard, Bethany L.; Fowler, Norma L.  Wide ecological amplitude of a
diversity-reducing invasive grass.  Biological Invasions 9:149-160.  2007.

Hickman, et al.  Effects of Old World Bluestem (Bothriochloa ischaemum) on
Food Availability and Avian Community Composition Within the Mixed-Grass
Prairie.  The Southwestern Naturalist 51(4):524-530. 2006.

Wiens, J. A. Habitat heterogeneity and avian community structure in North
American grasslands. American Midland Naturalist 91:195–213.  1974.

Winter, M.and Faaborg, J.  Patterns of area sensitivity in
grassland-nesting birds. Conservation Biology 13:1424–1436.  1999.





On Tue, May 14, 2013 at 6:06 PM, Backer, Dana <dana_backer at nps.gov> wrote:

> Yellow bluestem *(Bothriochloa ischaemum*) is a new species to Saguaro
> National Park (Tucson, Arizona). It showed up at an isolated spot in one of
> the riparian areas. I haven't been able to find much information about this
> plant.
>
> Folks in (www.texasinvasives.org) do not seem to like it. Does any one
> know how invasive it is? What are the ecological threats of this plant?
> Best control measures? Any information you can provide would be helpful.
>
> Thank you.
>
>
> Dana Backer, Restoration Ecologist
> Saguaro National Park
> 3693 S. Old Spanish Trail
> Tucson, AZ 85730
> Phone: 520-733-5179
> Fax: 520-733-5283
>
>
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