Scientific research has provided the foundation for
PlantRight recommendations. To share the wealth of knowledge, this page lists
important articles from peer-reviewed journals. We encourage you to learn more
about invasive plants by reading these papers and discussing them with your
community. If you would like to nominate an article to be included in our library, please send it to us using the contact us form. Don't hesitate to ask us a question if there's something you would like to hear more about!
Horticulture Industry and Invasive Plants
Burt, Jennifer W., et al. Preventing horticultural introductions of invasive plants: Potential efficacy of voluntary initiatives. Biological Invasions, Jan. 2007
This study sets out to measure the success of recent
industry efforts to control the introduction of invasive plants. It has become
clear that initial prevention of introduction is the most cost-effective and
efficient way of controlling invasive species. Just over half of industry
members currently voluntarily took part in preventative measures. Several
factors would increase participation in voluntary action, including awareness
and participation in trade associations. Results conclude that participation
will increase with improved outreach.
Crosson, Holly. 2005. Keeping Aquatic Plants in Their Place: Common Sense Tips to Protect Lakes and Rivers. Landscape Contractor Magazine, June 2005.
Information for water gardeners, pond owners, and
landscape contractors who install aquatic gardens. Description of the ways some
water plants can escape and cause problems in natural waterways, with
suggestion on steps water gardeners can take to prevent this from happening.
Harrington, Robin A., et al. Invasive Plants and the Green Industry. Journal of Arboriculture. January 2003, vol. 29, no. 1.
There are a many reasons why plants have been
introduced outside their native ranges, one of them being the introduction for
aesthetic reasons in the horticultural industry. In an effort to control the
introduction of invasive plants while minimizing impacts to the industry there
is a need for educational action as well as the compilation of information
pertaining to potential invasive species. This action ensures a proactive
approach with industry representation and input that could dramatically reduce
the introduction of invasive species.
Kelley, Kathleen M., et al. Invasive Plant Species: Results of a Consumer Awareness Knowledge, and Expectation Survey Conducted in Pennsylvania. Department of Horticulture, The Pennsylvania Sate University. University Park, PA. March 2006.
A survey of consumers at the 2004 Philadelphia Flowers
Show was conducted to quantify their attitudes towards invasive plants and
their behavior in purchasing and utilizing them. The survey concluded that over
80% of those surveyed were aware that potentially invasive plants were
available in the horticultural industry. Over 80% of those surveyed also
indicated that they would not purchase a plant they knew was invasive, and 40%
were considered to be "invasive savvy" and interested in excluding invasive
species from their yards.
The St. Louis Declaration On Invasive Plant Species. A product of: "The Workshop on Linking Ecology and Horticulture To Prevent Plant Invasions", February 2002
Findings, principles, and codes of conduct developed
for the prevention of invasive plant introduction. Codes of conduct established
included those for the government, nursery professionals, gardening public,
landscape architects, and botanical gardens and arboreta.
The Economics of Invasive Plants
Eisworth, M.E., W. S. Johnson, J. Agapff, T. D. Darden, and T. R. Harris. Economic Impacts from the Effects of Invasive Weeds on Outdoor Recreation: An Input-Output Model. University of Nevada-Reno Cooperative Extension. Special Publication SP 05-06.
Description of the costs of invasive plants on
hunting, fishing, and other recreation activities in Nevada.
Invasive Species: Federal and Selected State Funding to Address Harmful, Non-native Species. United States General Accounting Office. August 2000
Summary of Federal and State expenditures in
controlling invasive plants, and update on the status of the Invasive Species
Council. Federal spending for the years 1999 and 2000 amounted to over half a
billion dollars per year. In California expenditures were estimated at $85M
each year.
Pimentel, David, et al. Update on the Environmental and Economic Costs Associated with Alien-invasive Species in the United States. Ecological Economics, vol. 52, no. 3, 2005.
Alien-invasive species have been responsible for major
economic losses in agriculture, forestry, recreation, and other segments of the
U.S. economy; as well as causing harm to the indigenous environment. These
economic costs have been estimated at as much as $120 billion per year. In
addition the environmental costs are unmistakable by seeing that 42% of the
federally listed Endangered or Threatened species are at risk primarily due to
alien-invasive species. This paper is an update on the following document by
the same author.
Pimentel, David, et al. Environmental and Economic Costs Associated with Non-indigenous species in the United States. BioScience. 50(1): 53-65, 1999.
A valuation of the Economic and Environmental Costs
incurred through the introduction of Non-native species. Included are the costs
due to plants, mammals, birds, reptiles, fish, shellfish, microbes, and
diseases. The valued amount is in excess of $138 billion dollars annually.
Taylor, Brad W. and Rebecca E. Irwin. Linking Economic Activities to the Distribution of Exotic Plants. Proceedings of the National Academy of Sciences, December 21, 2004 vol. 101, no. 5.
This paper argues that there is a causal relationship
between economics and the ecology of the introduction of exotic plants. The
models tested propose to explain a correlation between certain population and
economic activities and the number of exotic plant species in a given area.
Invasion Biology
Bossard, C.C., J. M. Randall, and M. C. Hoshovsky (editors). 2000. Invasive Plants of California's Wildlands. University of California Press, Berkeley, CA.
This thorough book contains description of the biology, ecological impacts, and management strategies for 78 non-native invasive plants.
Clarke, Midori M. et al. Prevalence of different horticultural taxa of ivy (Hedera spp., Araliaceae) in invading populations. Biological Invasions. 8: 2006.
English Ivy includes many different species of ivy,
not all of which have invasive characteristics. This study has found through
DNA sampling, invasive ivy populations in the Pacific Northwest are mostly
derived from just one species, (Hedera hibernica). However, there are other
ivies that were not been addressed in this report that do have invasive
tendencies.
Groves, R. H. , R. Boden, and W. M. Lonsdale. 2005. Jumping the Garden Fence: Invasive Garden Plants in Australia and their Environmental and Agricultural Impacts. CSIRO Report for World Wildlife Fund - Australia. WWF-Australia, Sydney.
Australia, which has a similar climate to California
in some areas, has experienced many damaging plant invasions. This paper
outlines the serious economic, agricultural, and environmental damages from
invasive plants.
Harsh P. Bais. et al. Allelopathy and Exotic Plant Invasion: From Molecules and Genes to Species Interactions, Science: Vol. 301. no. 5638, 2003.
Presented here is a study of Spotted Knapweed, an
invasive plant in the Western United States, and the tendency to displace
native plants by exuding an inhibitive toxin from the root system. The result
is a growth inhibition of other plants.
Hobbs, Richard J., Mooney, Harold A. Broadening the Extinction Debate: Population Deletions and Additions in California and Western Australia. Conservation Biology, vol. 12, no. 2, April, 1998.
Deletion of a significant portion of a species
population is as much a concern as the extinction of the species all together.
Species additions in the form of introduction of invasive species are more
numerous than the extinction in any given area. These additions can often lead
to dramatic changes to ecosystems and can have a significant part in leading to
the extinction of populations. The two areas of California and Western
Australia, while very different, show similar trends in species extinctions,
range contractions, and invasions. Furthermore they both show that by focusing
on species extinction important human effects on biodiversity can be
overlooked.
Lambrinos, John. 2004. A tale of two invaders: The dynamic history of pampas grass and jubata grass in California. Cal-IPC News. Vol. 12, issue 3/4 (Fall 2004/Winter 2005).
This article from the California Invasive Plant
Council illustrates a history of the introduction and spread of two popular
ornamental plants that now invade wildlands in California.
Lambrinos, John G. The expansion history of sexual and asexual species of Cortaderia in California, USA. Journal of Ecology, 2001:89.
Presented is a comparison of the invasions of two
species of pampas grass which show different qualities of invasiveness. Also
considered is the temporal period of introduction and subsequent genetic
alteration that can influence invasiveness. The invasions of alien species seem
to be malleable processes, rather than an isolated event in time and place.
Lodge, David M., Biological Invasions: Lessons for Ecology. Trends in Ecology & Evolution. vol. 8, no. 4, p. 133-137, April, 1993.
Changes in species ranges as a result of population
invasions do occur naturally, with varying end results. However the accelerated
rate of invasion caused by human induced introductions may accomplish a
homogenization of the earth's biota in an unnatural way. These introductions
can have lasting impacts on ecosystems such as altering processes and cycles,
species to extinction, and reduction of total species richness. The potential
impacts of a species invasion are not limited to the species itself but the
target community as well; different communities will responded in invasions in
different ways.
Poulin, Jessica, et al. Genetic Diversity does not affect the Invasiveness of Fountain Grass (Pennisetum setaceum) in Arizona, California, and Hawaii. Department of Ecology and Evolutionary Biology, University of California at Irvine, Irvine, CA. Diversity and Distributions, 11, 241-247, 2005.
Fountain Grass has been a problem in the state of
Hawaii for some time and in its initial stages of invasion in the states of
California and Arizona. Fountain Grass has maintained little genetic variation,
but even little variation can allow for differences in invasive success.
Findings of this study suggest that invasion success of Fountain Grass is not
related to genetic variation. Alternatively variation of site conditions and temporal
periods may be the cause of variations in Fountain Grass invasion success.
Reichard, S. White, P. Horticulture as a Pathway of Invasive Plant Introductions in the United States. Bioscience. Feb 2001; vol. 51, no. 2; Research Library p. 103
The majority of woody invasive plant species can be
attributed to introduction through the horticultural and landscaping
industries. The introduction of potentially invasive horticultural plants can
be linked back to the beginning of the country. Today these plants are
introduced much the same way without fully realizing the potential of the
plants in a given area. The impacts are undisputable, but the method to control
invasive pants can not fall fully on the horticultural industry. An effort
should incorporate multiple disciplines working together utilizing multiple
actions.
Simerloff, Daniel, et al. Introduced species policy, management, and future research needs. Frontiers in Ecology and the Environment, 2005; vol. 3, no. 1.
Invasive species cause significant impacts to the
natural ecology of our lands, and current efforts are not sufficient enough to
control this problem. Presented here are the three stages of management:
prevention, eradication, and control; their current shortcomings; and
recommendations for improved results.
Westbrook, C., and K. Ramos. 2005. Under Siege: Invasive Species on Military Bases. National Wildlife Federation, Reston, VA.
Twelve case studies from Army, Navy, Air Force, and
Marine Corps installations illustrate the effects of invasive species on the
military - and on our national resources.
Wortman, Mark. Foreign Invaders Threatening Global Biodiversity, And the Public Hasn't Noticed-Yet. Environment Yale, The Journal of the School of Forestry & Environmental Studies. Fall 2004.
The spread of non-native species throughout the world
has reached devastating proportions. Non-native species run the gamut, from
viruses, insects, invertebrates, plants, and animals; and their pathways for
introduction are just as varied. These invaders can and have caused substantial
economic and social impacts. Addressing the impacts and possible prevention has
not been addressed until recently. Certain legislation and regulation has been
proposed to control the continued introductions, but it is suggested that
greater action may be needed.
Weed Risk Assessment
Leung, Brian, et al. An Ounce of Prevention or a Pound of Cure: Bioeconomic Risk Analysis of Invasive Species. The Royal Society. London. Nov. 2002
With the increasingly common problem of invasive
non-native species and the related impacts the need to quantify the costs of
the possible management strategies (prevention or control) is apparent. This
article presents a model to analyze risk of invasive species to economic
activities and the environment. The model identifies the optimum allocation of
resources to prevention verses control measures, as well as acceptable invasion
risk and consequences of invasion to optimal investments. Findings of this
model included, prevention as a good investments.
Reichard, Sarah H., and Clement W. Hamilton. Predicting Invasions of Woody Plants Introduced into North America. Conservation Biology. vol. 11, no. 1, 1997.
This paper presents a predictive model to classify
plants as being invasive, non-invasive, or requiring further research. This
model utilizes a hierarchal tree incorporating various plant attributes that
are indicative of invasiveness. Recommend actions here are: prevention of the
intentional introduction of invasive species, use of a hierarchal tree to
predict invasiveness, and continued research of plants that have consistently
not been invasive to further knowledge of invasiveness.
Williams, Peter A. A Weed Risk Assessment Model for Screening Plant Imports into New Zealand. Manaaki Whenua - Landcare Research. July 1996.
New Zealand has established a Weed Risk Assessment
(WRA) to be applied to screening plants to determine their potential
invasiveness. The assessment entails creating a numerical score sheet for each
potential plant. This method allows for a certain amount of calibration for
creating a definitive evaluation. This assessment has the ability to exclude
all major weeds, but can result in the exclusion of many non-weeds as well. The
benefit of this WRA is that it is objective with clear assumptions regarding
weed attributes.
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