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Global Invasive Species Team listserve digest #092
Wed Sep 05 2001 - 16:52:27 PDT
--CONTENTS--
1. Clarification on weed-free topsoil (Maine)
2. Weed pamphlet from WIST (Global)
3. Upcoming workshops/meetings (Nationwide, USA)
4. NFWF reminder (Nationwide, USA)
5. Literature reviews (Global)
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1. Clarification on weed-free topsoil (Maine, USA)
From: Nancy Sferra (nsferra(at)tnc.org)
I just wanted to clarify an item sent in by Ross Geredien in Invasive
Species digest #91. Our restoration project in Maine did not rely on
imported topsoil. We stockpiled topsoil from an intact sandplain
grassland where a pipeline was going through and used that stockpiled
topsoil for the restoration of the construction site. The seed bank in
the stockpiled topsoil was a major contributor to the success of the
revegetation of that site.
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2. Weed pamphlet from WIST (Global)
From: TunyaLee Martin/WIST (tamorisawa(at)ucdavis.edu)
Do you need to explain to your community why that "pretty flower" should
be removed from a natural area, or are you having trouble explaining what
a "weed" is? The Wildland Invasive Species Team is ready to help!
We are pleased to announce the internet publication of a pamphlet, "Weeds
in the Wild: Weed Management in Natural Areas". The pamphlet is chock full
of information on invasive plants and animals. It is one page,
double-sided, and can easily be printed on a black/white or color printer,
and then folded for site visitors, partners, and neighboring landowners.
If it is well received, we may follow it up with similar pamphlets on
other topics. Check it out! We have it on line at:
http://tncinvasives.ucdavis.edu/outreach.html
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3. Upcoming workshops/meetings (Nationwide, USA)
From: Barry Rice (bamrice(at)ucdavis.edu)
In case you have not noticed, we maintain on our web site a list of
approaching meetings that may be of particular interest to weed bashers.
Right now, at http://tncinvasives.ucdavis.edu/meetings.html you can see notes,
information, and links on two meetings.
First, the 28th Annual Natural Areas Conference (3-6 October, Florida)
will include an Invasive Species Symposium hosted by the National
Association of Exotic Pest Plant Councils and the Florida Department of
Environmental Protection, Bureau of Invasive Plant Management. The plenary
guest is Dr. Dan Simberloff. (Thanks for Ruark Cleary for news of this
meeting.)
The second is "Phragmites australis: A Sheep in Wolf's Clothing?" (6-9
January 2002, New Jersey), is dedicated to the complex issues surrounding
Phragmites australis. Is it native? Is it really the villain it is often
claimed to be?
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4. NFWF reminder (Nationwide, USA)
From: Barry Rice (bamrice(at)ucdavis.edu)
Do not forget that the due date for NFWF (National Fish and Wildlife
Foundation) grant proposals for the "Pulling Together Initiative" is
November 6. NFWF funds projects which "...benefit multiple species,
achieve a variety of resource management objectives, and/or lead to
revised management practices that reduce the causes of habitat
degradation. A special emphasis is placed on larger projects that
demonstrate a landscape-level approach and produce lasting, broad-based
results on the ground."
Pulling Together Initiative proposals are particularly likely to be
successful if they involve Cooperative Weed Management Areas, or some
analogous consortia of multiple partners.
These grants average about $50,000, but assume that 1/2 the funds are
raised by the grantee via matching funds. For more information, look to
the web site at: http://www.nps.gov/plants/nfwf/02rfp.htm
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5. Literature reviews (Global)
From: John Randall/WIST (jarandall(at)ucdavis.edu)
D'Antonio, C.M., R.F. Hughes and P.M. Vitousek. 2001. Factors influencing
dynamics of two invasive C4 grasses in seasonally dry Hawaiian woodlands.
Ecology 82(1): 89-104.
This work examines a case in which a previously established invasive
species is pushed out by a more recent arrival and reveals the conditions
and physiological mechanisms that allow this to occur. The perennial C4
bunchgrass Schizachryum condensatum from the American tropics and
subtropics is now an abundant invader in Hawaii's seasonally dry
woodlands. Following fires, however, this species is often replaced by
another invasive C4 grass native to Africa, Melinus minutiflora (molasses
grass). The authors' experiments indicated that molasses grass
establishment is suppressed by the dense shade cast by established S.
condensatum stands. Molasses grass establishment was promoted by removal
of S. condensatum but not by nutrient addition alone. When seeds of both
species were started at the same time the molasses grass seedlings
consistently outcompeted S. condensatum, regardless of light or nutrient
conditions. The authors concluded that where S. condensatum is already
established molasses grass can invade only following fires which eliminate
or sharply reduce the former species above-ground biomass. Molasses grass
seed is generally abundant in these areas and it quickly becomes
established and eventually replaces S. condensatum through resource
competition. The authors also concluded that molasses grass could readily
invade unburned woodland if it was not already dominated by other invasive
bunchgrasses.
Leslie, A.J., and J.R. Spotila. 2001. Alien plant threatens Nile
crocodile (Crocodylus niloticus) breeding in Lake St. Lucia, South Africa.
Biological Conservation 98: 347-355.
Chromolaena odorata is an herbaceous perennial in the Asteraceae which is
native to the American tropics (including south Florida) but invasive in
parts of Africa, Asia and on many tropical and subtropical islands. It is
now abundant around Lake St. Lucia and adjacent wetlands which lie near
the Indian Ocean in South Africa's Kwazulu-Natal province and are the
southernmost extent of the Nile crocodile's breeding range. The authors
found that dense C. odorata root mats sharply reduced availability of
crocodile nest sites at one study location. The heavy shade cast by C.
odorata at every site examined also reduced soil temperatures so that they
fell below a threshold at which the eggs yield roughly equal numbers of
female and male offspring and perhaps even below the threshold which
allows embryonic development to occur at all. The authors concluded that
where C. odorata is not controlled, the highly female-biased sex ratio of
nestlings will result in sharp decline and eventual extirpation of the
Nile crocodile population.
Larson, D.L., P.J. Anderson, and W. Newton. 2001. Alien plant invasion
in mixed-grass prairie: effects of vegetation type and anthropogenic
disturbance. Ecological Applications 11(1): 128-141.
The researchers assessed frequency of non-native invasive species on more
than 1300 transects in the two units of Theodore Roosevelt National Park
in western North Dakota to determine whether anthropogenic disturbance or
biotic and physical factors better explain variations in abundance of
invaders there. Each transect was classified beforehand by park unit,
vegetation type and as disturbed (here defined as within 100 mm of roads,
trails, buildings, etc.) or undisturbed. Invasive species were present in
all vegetation types but mesic communities had more species of invaders
and higher frequencies of most species than did drier community types.
Surprisingly, frequencies of six of the seven most abundant invaders in
the Park (Melilotus officinalis, Poa pratensis, Tragopogon dubius,
Taraxacum officinale, Bromus japonicus, Euphorbia esula) were best
explained by vegetation or vegetation and unit. Frequencies of Bromus
inermis (smooth brome) and several less abundant species were best
explained by vegetation type and disturbance or disturbance alone. The
authors note that there was a strong element of stochasticity in frequency
differences between the two units of the Park for many invasive species
which suggests that chance may play an important role in many invasions.
Because vegetation type was the best predictor of frequency of non-native
plants in aggregate and for 10 of the 17 species detected the authors
suggest that it be explicitly taken into account in the design of invasive
plant monitoring and management plans.