Invasive Species in Context

Gary Lovett

Forest Ecologist

Cary Institute Science and Management Forum: Invasive Species in the Hudson Valley

Saturday, March 21, 2015

Zebra mussel Multiflora rose Emerald ash borer

Alien invasive species: Unwanted byproducts of global trade

Largest shipping routes in 2007 (Kazula et al. 2010)

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Value of U.S. Imports(Billions of 2010 $ per year)

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Trade goes both ways…

Smooth cordgrass (Spartina) invasive in Asia Grey Squirrel invasive in Britain

Red eared slider invasive in many places Fall webworm invasive in China

Focus on Early Stages of Invasion

Likelihood of successful eradication decreasesCost of control efforts increasesCosts shift from importer to general population

Graphic from Department of Environment and Primary Industries , Victoria, Australia

Economic Costs of Invasive Species

• An economic “externality” to importers. Costs largely paid by the public

• Economic costs are not yet fully reckoned

• One estimate of aggregate cost: $120 billion per year in the U.S. (Pimentel et al. 2005)

• Does not include non-market values

Most Important Pathways of Introduction

Terrestrial plants• Plant trade• Intentional

introductions

Forest pests• Plant trade• Wood packing

material (crates, pallets, spools)

Aquatic species• Plant trade• Ballast water• Ship hulls• Canals• Pet trade• Aquarium trade

Plants Herbivores

Plant pathogens

Predators

Decomposers

Native primary producers

Detritus and dead organic matter

Native predators

Native decomposers

Native herbivoresAilanthus

Gypsy moth

Beech bark disease

Nightcrawler

Snakehead

• Water use

• Physical structure

• Fire

• Wildlife habitat

Other Ecological Impacts

Introduced Forest Insects and Diseases:Impacts and Options

The Rogue’s Gallery(A Partial List)

• Chestnut blight

• Dutch elm disease

• Gypsy moth

• Hemlock woolly adelgid

• Balsam woolly adelgid

• White pine blister rust

• Dogwood anthracnose

• Emerald ash borer

• Beech bark disease

• And the list goes on and on……

• And waiting in the wings:

– Asian longhorned beetle

– Sudden oak death (Phytophthora ramorum)

– Sirex wood wasp

From Liebhold et al. Diversity and Distributions (2013)

Biological Pollution

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All Insect Pests

WoodBorers

Value of Imports

All insects: 2.6 per year

since 1850

Wood borers: 1.2 per year since 1985

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All Insect Pests

WoodBorers

All insects: 2.6 per year

since 1850

Wood borers: 1.2 per year since 1985

The number of insect pests has continued to increase…

… but not as fast as trade

Data from Aukema et al. 2010

Death of trees

Warming of streams may impact fish

Impacts of Forest Pests Reverberate Though the Ecosystem

Short- and long-term changes in carbon storage

and nutrient losses

Decline of some bird species

Decline of old-growth forests

Hemlock Woolly Adelgid

Economic Impacts• Impacts of invasive insects estimated at > $5B per year

– Forestry impacts small compared to urban and suburban impacts

– Largest costs borne by homeowners and municipal governments

– Costs include takedown and replacement of street trees and yard trees, lost property value

Worcester, MA eradication of Asian longhorned beetle

Before After

Photos from APHIS PPQ

(from Aukema et al. 2011)

Focus on Major Pathways of Introduction

Live plants for horticultureWood packing material

• Current regulations require heat treatment or fumigation of wood packing material

• Have been shown to be partially effective, reducing pest introductions by 30-50%

• Could still result in the number of wood-boring beetle species tripling by 2050!

• Current regulations for most plants require a certificate from country of origin and an inspection upon entry

• Estimated to intercept only 28% of imported insects on live plants

Leung et al 2014 Liebhold et al 2012

Can This Problem be Solved? Eradication of established pests is

virtually impossible, but we can slow their spread and buy some time

Biological control has potential but is difficult and risky

Action is needed at the federal level to control the major vectors: live plants for the nursery trade and wood packing material

Policy Options to Prevent Establishment

What can you do about this?

• Use native rather than imported plants in landscaping

• Don’t move firewood

• If managing a forest in response to pest outbreaks, consider:• Impacts of harvesting on the ecosystem• Impacts of pesticides• Long-term health of the tree population

• Recognize that this is a national problem of border protection and complain loudly to your representatives in Congress