Department
of Natural Resources
122E Fernow Hall, Cornell University
Phone: 607-255-5314
Fax: 607-255-0349
E-mail: bb22@cornell.edu
Webpage: www.invasiveplants.net
I am an
ecological generalist with wide ranging interests (plants, birds, insects,
mammals, amphibians) in aquatic and terrestrial systems. My academic training
is in ecology, particularly entomology and limnology but with a focus on
applied entomology. I am particularly intrigued by potential ecosystem effects
associated with increase and decline of invasive plants species in natural
areas. Invasive plants are likely to change native species diversity, ecosystem
processes, and food webs but for most species we have very little quantitative
data to support management and control. The goal of the Ecology and Management
of Invasive Plants Program, which I direct, is to assemble multidisciplinary
teams of students and other professionals to engage in scientific research and
the collection of sound data on the impact of invasive plant species. While the
focus of our work are species invasive in the
northeastern
An
associated goal is the development and improvement of the scientific basis of
biological weed control programs. For most of the invasive plant species in
North America, chemical, mechanical, or physical measures provide only
temporary control. The careful planning and implementation of biological weed
control programs offers an ecologically sound alternative control strategy. I
believe that by understanding and documenting the long-term impacts of spread
and decline (through biocontrol) of invasive plant
species on native species and their food webs, important improvements in the
safety and success rate of this technology can be achieved. An important aspect
of improving adoption and implementation of biocontrol
programs are partnerships with agencies and private citizens. We develop
standardized monitoring
protocols that balance ease of implementation with scientific
sophistication but allow citizen participation in scientific data collection
(please explore the various opportunities for participation offered through
this webpage).
In
addition, I am interested in factors contributing to the invasiveness of plant
species. Most plant species arriving outside their traditional distributions
through human aided transport (accidentally or purposefully) never become
establish. Of those that establish, only few (about 10%) escape and naturalize
(establish self-sustaining populations without human help). Of those that
naturalize about 10% become invasive. In North America about 5000 plant species
have naturalized and approximately 500 are recognized as invasive. The
intriguing question is: what factors allow certain plant species to become
invasive (in fact we know that invasiveness can evolve)? I have proposed the
Evolution of Increased Competitive Ability (EICA) hypothesis (Blossey and Nötzold 1995), which explains the invasiveness of certain
plant species through interaction of herbivores with their host plant. Plants
that were under high herbivore pressure in their native range experience
enemy-free space in their new range. This absence of natural enemies allows
introduced plants to shift resource from herbivore defense to increased
vegetative growth or seed output, allowing them to outcompete native plants. The importance of natural
enemies is highlighted by the fact that invasiveness of plants can be reversed
through the release of biological control agents (but not always).
Approaches
In
general, we use a combination of long-term monitoring (often at invasion
fronts) and experiments. I strongly believe that reliable predictions about
behavior of organisms or natural systems can only be derived at through field
or common garden experiments and field observations. While the ability to
manipulate large systems is limited, concerns over appropriateness of spatial
and temporal scales when investigating invasions need to be paramount.
Long-term monitoring can be a powerful (but greatly underutilized and underfunded) tool to understand potential ecosystem impacts
of non-indigenous plants.
1. Biological control of garlic mustard (Alliaria petiolata). Funded since 1998 through support by various state Departments of
Natural Resources, Native Plant Societies, private donors, the Strategic
Environmental Research and Development Program, and the US Forest Service.
2. Impact of invasive
plants on abundance and fitness of woodland salamanders. Funded
through IL Department of Natural Resources and US EPA.
3.
Developing biological
control of Phragmites australis. Funded since 1998 through grants from NY, RI and National Sea
Grants, The US Fish and Wildlife Service, The US Bureau of Reclamation, and the
New Jersey Public Service Enterprise Group. A frequent PI or Co-Pi on
these grants is Richard Casagrande and his team from
the University of Rhode Island.
4.
Morphological
differences and herbivore resistance in native and introduced genotypes of P. australis. (with R. Casagrande as PI) Funded by RI and
5. Evaluating the success of biological control of purple
loosestrife. Various projects funded through US Bureau of Reclamation and NY
Department of Environmental Conservation, Bureau of Wildlife
6. Impact
and development of biological control of Japanese knotweed. Funded
through US
Blossey, B. 1999. Before, during,
and after: the need for long-term monitoring in invasive plant species
management. Biological Invasions 1:301-311.
Blossey, B., and
T. R. Hunt-Joshi.
2003. Belowground herbivory by insects: influence on
plants and aboveground herbivores. Annual Review of Entomology 48:521-547.
Blossey, B., and
R. Nötzold. 1995. Evolution of increased competitive ability in invasive
nonindigenous plants: a hypothesis. Journal of
Ecology 83:887-889.
Blossey, B., V.
Nuzzo, H. Hinz, and E. Gerber. 2001a.
Developing biological control of Alliaria petiolata (M. Bieb.) Cavara and Grande (garlic mustard). Natural Areas Journal 21:357-367.
Blossey, B., L.
C. Skinner, and J. Taylor. 2001b. Impact and management of purple
loosestrife (Lythrum salicaria) in
North America. Biodiversity and Conservation 10:1787-1807.
Byers, J. E.
2002. Impact of non-indigenous species on natives enhanced by anthropogenic
alteration of selection regimes. Oikos 97:449-458.
Callaway, R. M.,
and E. T. Aschehoug. 2000. Invasive plants versus
their new and old neighbors: a mechanism for exotic invasion. Science 290:521-523.
Chapin, F. S., E. S. Zavaleta, V. T. Eviner, R. L.
Naylor, P. M. Vitousek, H. L. Reynolds, D. U. Hooper,
S. Lavorel, O. Sala, S. E. Hobie, M. C. Mack, and S. Diaz. 2000. Consequences of
changing biodiversity. Nature 405:234-242.
Crawley, M. J. 1987. What makes a
community invasible? Pages 429-453 in A. J. Gray, M. J. Crawley, and P. J.
Edwards, editors. Colonization, Succession and
Stability. Blackwell Scientif
Publications, Oxford.
Davis, M. A., J.
P. Grime, and K. Thompson. 2000. Fluctuating resources in plant communities: a
general theory of invasibility. Journal of Ecology 88:528-534.
Ellstrand, N. C., and K. Schierenbeck. 2000. Hybridization as a stimulus for the evolution of
invasiveness in plants? Proceedings of the National Academy of Sciences 97:7043-7050.
Farnsworth, E.
J., and D. R. Ellis. 2001. Is purple loosestrife (Lythrum salicaria) an invasive threat to freshwater wetlands? Conflicting evidence from several ecological metrics.
Wetlands 21:199-209.
Gray, A. J. 1986. Do invading
species have defineable genetic chracteristics?
Philosophical Transactions
of the Royal Society of London B 314:655-674.
Hendrix, P. F.,
and P. J. Bohlen. 2002. Exotic earthworm invasions
in North America: ecological and policy implications. BioScience
52:801-811.
Keane, R. M.,
and M. J. Crawley.
2002. Exotic plant invasions and the enemy release hypothesis. Trends in
Ecology and Evolution 17:164-170.
Kennedy, T. A.,
S. Naeem, K. M. Howe, J. M. H. Knops, D. Tilman, and P. Reich. 2002. Biodiversity as a barrier to ecological
invasion. Nature 417:636-638.
Klironomos, J. N. 2002. Feedback with soil
biota contributes to plant rarity and invasiveness in communities. Nature 417:67-70.
Kolar, C. S., and D.
M. Lodge.
2002. Ecological predictions and risk assessment for alien fishes in North
America. Science 298:1233-1236.
Kourtev, P. S., J. G. Ehrenfeld, and M. Häggblom. 2002. Exotic plant species alter
the microbial community structure and function in the soil. Ecology 83:3152-3166.
Lee, C. E. 2002. Evolutionary genetics of invasive species. Trends in Ecology
& Evolution 17:386-391.
Levine, J. M.,
M. Vilà, C. M. D'Antonio,
J. S. Dukes, K. Grigulis, and S. Lavorel. 2003. Mechanisms underlying the
impacts of exotic plant invasions. Proceedings of the Royal
Society of London B DOI
10.1098/rspb.2003.2327.
Lonsdale, W. M. 1999. Global
patterns of plant invasions and the concept of invasibility.
Ecology 80:1522-1536.
Mack, R. N., D. Simberloff, W. M. Lonsdale, H. Evans, M. Clout, and F. A. Bazzaz. 2000. Biotic invasions: causes, epidemiology,
global consequences, and control. Ecological Applications 10:689-710.
Maron, J. L., and M. Vilà. 2001. When do herbivores affect plant invasions? evidence for the natural enemies and biotic resistance
hypotheses. Oikos 95:361-173.
Mitchell, C. E.,
and A. G. Power.
2003. Release of invasive plants from fungal and viral pathogens. Nature 421:625-627.
National
Research Council.
2002. Predicting invasions of nonindigenous plants
and plant pests. National Academy Press, Washington D. C.
Saltonstall, K. 2002. Cryptic
invasion by non-native genotypes of the common reed, Phragmites australis, into North America.
Proceedings of the National Academy of Sciences 99:2445-2449.
Schmidt, K. A.,
and C. J. Whelan.
1999. Effects of exotic Lonicera
and Rhamnus
on songbird nest predation. Conservation Biology 13:1502-1506.
Torchin, M. E., K. D.
Lafferty, A. P. Dobson, V. J. McKenzie, and A. M. Kuris. 2003. Introduced species and
their missing parasites. Nature 421:628-630.
Yela, J. L., and J.
H. Lawton.
1997. Insect herbivore loads on native and introduced plants: a preliminary
study. Entomologia Experimentalis
et Applicata 85:275-279.