Will Climate Change Cause the Spread of Invasive Plants

Researchers compared exotic plant species that had recently established in Millingerwaard, a nature preserve in The Netherlands, with related native plant species from the same area. (Credit: iStockphoto/Ruud De Man)

This could end up being a real economic and logistic headache in the future. Some of our most invasive species could spread into areas where it was previously kept in check by the cold. Would the most aggressive invaders run rampant? Would other species that were well behaved in there native areas wreak havoc as they migrate northward? The cost of eradication programs for invasive species is staggering. Time and resources are wasted, that could be used for other areas of plant conservation. Climate change is happening whether its natural or hastened by humans. I'm not here to debate that today. The bottom line is this problem has to worked from both ends. First, by stopping these invasives from getting loose. We must continue to introduce new plants but in a sensible way so invasive species don't have a chance to proliferate. Second, we have to stop the pollution that is causing the warming. If we don't we will continue to deal we these issues!
Eric

Why is it so bad?
Invasive species can rapidly and seriously degrade the quality of wild lands by altering natural processes and reducing biodiversity. At the same time, control methods that land managers use can also affect the habitat. Preserve managers must determine which control method is most effective against the invasive species, while being the least damaging to the ecosystem. For example, when working with a habitat that is dominated by weeds, preserve managers are justified in using harsh tactics. Meanwhile, if there are just a few weeds invading an otherwise pristine environment, a more delicate approach is appropriate. Invasive species control in natural habitats can be tricky![1]

The Economic Impact
The annual losses to the Great Lakes Region, because of ship-borne invasive species, is at least $200 million. Lodge, D., and Finnof, D. 2008. Annual Losses to Great Lakes Region by Ship-borne Invasive Species at least $200 Million. Great Lakes United (www.glu.org).

Efforts to control Purple Loosestrife (Lythrum salicaria) cost $45 million per year. See: Pimentel, D., Lach, L., Zuniga, R., and Morrison, D. 2000. Environmental and economic costs of nonindigenous species in the United States. Bioscience 50: 53-65.

Leafy spurge (Euphorbia esula) costs ranchers in ND, SD, MT, WY more than $144 million a year. See: Bangsund, D.A., and Leistritz, F.L. 1991. Economic impacts of leafy spurge on grazing lands in the northern Great Plains. NDSU Agriculture Economic Report No. 275-S.

The annual US cost from invasives is $120 billion, with over 100 million acres being affected (i.e. the size of California). See: Pimentel, D., Zuniga, R., and Morrison, D. 2005. Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics. 52: 273-288.

African lovegrass (Eragrostis plana) destroyed the pasture value of 10% of southern grazing lands and severely damaged the area's cattle industry. Annual losses are calculated at $30 million per year. See: Rosa, F., Ramos, J.V., and Ziller, S. 2007. Economic impacts of Eragrostis plana on the Southern Brazil grasslands. Biological Invasions (in prep.).

The estimated damage from invasive species worldwide totals more than $1.4 trillion--five percent of the global economy. See: Pimentel, D., McNair, S., Janecka, J., Wightman, J., Simmonds, C., O'Connell, C., Wong, E., Russel, L., Zern, J., Aquino, T. and Tsomondo, T. 2001. Economic and environmental threats of alien plant, animal, and microbe invasions. Agriculture, Ecosystems and Environment 84: 1-20[ 2]

Moving North

GAINESVILLE, Fla. — Plants that range northward because of climate change may be better at defending themselves against local enemies than native plants.

So concludes a team of scientists including a University of Florida geneticist. The team’s findings, reported in today’s online edition of Nature, suggest that certain plants could become invasive if they spread to places that were previously too cold for them.

“This paper is the first to suggest that the mechanisms that aid invasive species when they move from one continent to the next may actually work within continents when climate change gradually extends the distributional range of a species,” said Koen J.F. Verhoeven, an evolutionary biologist at The Netherlands Institute of Ecology. “Plants may be able to outrun, so to speak, their enemies from the southern range.”

Often, exotic plants and animals are introduced to new continents or geographic regions by travelers and commerce. Separation from their natural enemies can drive their invasive success in the new range. But, increasingly, the distribution of many species is shifting because of climate change and changes in land use.

Led by scientists Tim Engelkes, Elly Morriën and Wim van der Putten of The Netherlands Institute of Ecology, with collaborators from the University of Florida, Wageningen University and Leiden University, the researchers compared exotic plant species that had recently established in Millingerwaard, a nature preserve in The Netherlands, with related native plant species from the same area.

“We set out to see whether the native and exotics responded differently to natural enemies such as herbivores or microorganisms in the soil,” said Lauren McIntyre, an associate professor of molecular genetics and microbiology in UF’s College of Medicine and a member of the UF Genetics Institute. “UF helped develop a statistical model that took into account the experimental design and had good power to detect the effects of herbivory.”

Scientists grew six exotic and nine native plant species in pots with field-collected soil from the Millingerwaard area, allowing natural soil pathogenic microbes to accumulate in the pots. Then they removed the plants and replanted the soils with the same plant species.

The growth of native plants was reduced far more than the growth of exotic species, indicating natives were more vulnerable to natural soil-borne microbes.

In addition, all plant species were exposed to North African locusts and a widespread species of aphid. These herbivores were not expected to show a preference for either the native or the exotic species. But they preferred the native plants and left the exotic ones relatively alone.

Researchers say the findings help to better assess the ecological consequences of climate change. The success of exotic plants expanding their range in response to warmer climates may be comparable to invasive exotic plant species that arrive from other continents, representing an additional threat to biodiversity.[3]

[1] http://tncinvasives.ucdavis.edu/methods.html
[2] http://tncinvasives.ucdavis.edu/economics.html
[3] http://news.ufl.edu/2008/11/19/roving-plants/

Will Climate Change Cause the Spread of Invasive Plants by Eric Bronson is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.