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Global Invasive Species Team listserve digest #103
Fri Apr 05 2002 - 16:41:56 PST
--CONTENTS--
1. Noxious, invasive plant meeting 25-26 April (Arizona, USA)
2. Oxalis pes-caprae (California, USA)
3. Drills and Sidewinder (Michigan, USA)
4. Sidewinder injector systems (California, USA)
5. Literature reviews (Global)
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1. Noxious, invasive plant meeting 25-26 April (Arizona, USA)
From: Laura Moser (lmoser(at)fs.fed.us)
To all who have an interest in noxious, invasive plants on wildlands and
rangelands in Arizona, there will be a Summit held at the Radisson Hotel
in Tucson, April 25-26. The Summit will be an excellent opportunity for
land managers, educators, legislators, and members of the general public
to come together to learn from experts and share information about
successes and challenges in noxious, invasive plant management, with
special emphasis on Arizona.
The registration form has been posted on the WIST web site, at:
http://tncinvasives.ucdavis.edu/meetings.html
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2. Oxalis pes-caprae (California, USA)
From: Andrea Pickart (andrea_pickart(at)r1.fws.gov)
We have a new infestation that is invading dune habitats in northern
California. It is most severe in degraded dunes, but is also in native
areas. I found advice on the UC Pest control site that recommends
preventing flowering (to prevent bulb formation) and solarization to kill
bulbs. Has anyone had to deal with this weed in wildlands?
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3. Drills and Sidewinder (Michigan, USA)
From: Jack McGowan-Stinski (jmcgowan-st(at)tnc.org)
Regarding herbicide drills mentioned in listserve posting #101...
We use cordless drills (DeWalt), with extra battery packs, a 3/8 inch
drill bit, a laboratory squeeze bottle to drill-and-fill; a drill holster
helps so you can juggle between the drill and squeeze bottle, and we also
mark trees that have been treated with tree marking spray paint.
The advantage of using above method is the drill can also be used for
non-herbicide projects; I am guessing that the price would be about the
same, but the Sidewinder only has one function. I have explored a flexible
squeeze-bag with a tube attached to the drill that allows you to drill a
hole, back the drill bit out, move the drill up and insert the flexible
tube and squeeze bag; this worked well in that it was a one-handed
operation, but it contaminated the drill.
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4. Sidewinder injector systems (California, USA)
From: Ken Moore (ken(at)wildwork.org)
I haven't used this particular system, but I have used a cordless drill
with a 5/16" bit and simply squirted a 50% glyphosate solution directly
into the holes with good success on acacia, black locust (Robinia
pseudoacacia), and eucalyptus.
Large eucalyptus trees have a thick secondary bark which requires an extra
long drill bit to penetrate to the cambium layer. The extra friction of a
longer bit is a big drain on the battery, and even though I use an 18 volt
drill, I can drain a battery in 1 or 2 large trees (48" DBA or more).
The Sidewinder uses a 12V drill, which has considerably less capacity than
the 18V, so I think its usefulness would be limited to smaller trees
unless you want to purchase and carry many extra batteries.
The holes need to be 1-2" apart, around the entire circumference. I drill
at a downward angle, to provide a receptacle for the herbicide. This is
best done in early fall. Sometimes a second treatment is required.
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5. Literature reviews (Global)
From: John Randall (jarandall(at)ucdavis.edu)
**Study with implications for use of distantly gathered plant material for
restoration:
Seliskar, D.M., J.L. Gallagher, D.M. Burdick and L.A. Mutz. 2002. The
regulation of ecosystem functions by ecotypic variation in the dominant
plant: a Spartina alterniflora salt-marsh case study. Journal of Ecology
90: 1-11.
This paper provides evidence of another reason why it may be inappropriate
to use seeds and cuttings of native species gathered from distant sites in
restoration plantings: different ecotypes of a dominant species may differ
so much in important characteristics that they have significantly
different effects on rates of ecosystem functions. This adds to arguments
that plants gathered from distant sites might differ genetically and be
poorly adapted for the local climate and so have a poor chance of
surviving or conversely, that they could do well and swamp out distinctive
local genotypes through competition and or interbreeding with local types.
The authors of this study gathered 5 to 7 sods of 20-40 culms of Atlantic
salt-marsh cordgrass from 1 hectare sites on the coast of Massachusetts,
Delaware and Georgia and then propagated them in a common garden in
Delaware for 6 years. The plants reproduced vegetatively but maintained
phenotypic differences typical of their latitudes. Four replicate
plantings of each of these three ecotypes were then made in an
artificially constructed salt marsh on the Delaware coast and for the next
5 years morphological traits and ecosystem functions were measured in each
planting. The magnitude and expression of most ecosystem functions
measured remained distinct between the different ecotypes. End of season
aerial biomass, below-ground biomass, root and rhizome distribution with
depth, canopy height, stem density and carbohydrate reserves were more
similar to values measured in each ecotype's native range, than to values
measured in natural Delaware populations. For example, all root and
rhizome biomass of the MA ecotype was less than 15cm deep while 8% of
biomass of the GA type was greater than 30 cm deep. These characteristics
apparently had significant influence on respiration of the microbial and
soil communities and edaphic algal chlorophyll (an indicator of edaphic
algal abundance) which differed significantly among ecotypes. Edaphic
chlorophyll was higher under the MA and DE ecotypes which had shorter,
less dense canopies than the GA type. In addition, more than twice as
many larval fish (Fundulus heteroclitus, common name mummichog) were
caught in plots of the MA ecotype than in DE and GA ecotypes, apparently
because foraging was better in these lower density, low canopy-height
stands.
The authors note that the different ecotypes were shaped by historic
environmental forces but also exhibit some plastic responses molded by
current environmental forces. In turn, the dominant S. alterniflora
exhibits keystone resource activity -serving as a major fuel for the food
web - AND keystone modifier activity - modifying the habitat and so
favoring or inhibiting various other species. Because the different
ecotypes produce different amounts of biomass with different ratios of
stem to root mass and different placement of the roots and rhizomes with
depth in the soil they support different levels of microbial respiration
in the soil, on its surface and on detrital organic matter. The different
ecotypes also provide different habitat structure, with the taller, denser
stands from GA excluding more light and keeping the sediments cooler, etc.
**Threshold of abundance for impact of invader?
Standish, R.J., A.W. Robertson and P.A. Williams. 2001. The impact of an
invasive weed Tradescantia fluminensis on native forest regeneration.
Journal of Applied Ecology. 38(6): 1253-1263.
This study examined whether an invasive understory herb suppressed
regeneration of native tree and shrub species and whether there was a
threshold level of its abundance above which this occurred. Tradescantia
fluminensis is a ground-smothering perennial herb native to South America
which has invaded forest understories in New Zealand, where this study was
conducted, and in eastern Australia and Florida. Native forest species
seedling richness and abundance decreased exponentially with increasing T.
fluminensis abundance which the authors attributed to decreasing light
levels beneath the T. fluminensis. Under 100% T. fluminensis cover
(approximately 500 g m-2) available light was less than 1% of full light.
Six different native species had different tolerances to T. fluminensis
biomass with the least tolerant Micropiper excelsum abundance reduced to
50% of its maximum levels by just 12 g m-2 of T. fluminensis and the most
tolerant Dysoxylum spectabile reduced to 50% of its maximum at 40 g m-2.
The authors estimated that emergence of native woody species seedlings
above the level of T. fluminensis blankets can occur only where T.
fluminensis cover is less than 200 g m-2. Fortunately, T. fluminensis
cover is itself reduced under moderately dense tree canopy cover.