1) Invasive plants – What are they?b) Ecological definitions and characterizations

Nevada’s Coordinated Invasive Weed Strategy (http://agri.nv.gov/nwac/weedplan_p.htm)

1) Invasive plants – What are they?b) Ecological definitions and characterizations

Nevada’s Coordinated Invasive Weed Strategy• Prepared by Nevada Weed Action Committee (NV Dept. Ag)• Included local, state, and federal agencies/governments; NCE;

private sector

1) Invasive plants – What are they?b) Ecological definitions and characterizations

Nevada’s Coordinated Invasive Weed Strategy• Nevada Weed Action Committee• Uses USDA definition of noxious weeds: “species of plants that

cause disease or are injurious to crops, livestock or land, and thus are detrimental to agriculture, commerce or public health”

1) Invasive plants – What are they?b) Ecological definitions and characterizations

Nevada’s Coordinated Invasive Weed Strategy• Nevada Weed Action Committee• Noxious weed definition• Invasive weeds often share characteristics such as

Highly competitive Cause environmental degradationExotic Easily spreadHighly aggressive Are difficult to controlCause economic lossAugment wildfires

1) Invasive plants – What are they?b) Ecological definitions and characterizations

Nevada’s Coordinated Invasive Weed Strategy• Nevada Weed Action Committee• Noxious weed definition• Invasive weed characteristics• “Species of concern”

o Species that have potential to cause greatest impact on Nevada’s ecosystem and economic well being

o Not all are on noxious weed listo Includes:

Red brome CheatgrassWhitetops KnapweedsYellow starthistle ThistlesRush skeletonweed MedusaheadSaltcedar Watermilfoil

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy

The Nature Conservancy (http://tncweeds.ucdavis.edu/common.html)Invasive species are:• Spread from human settings into wild• Once wild, continue to reproduce• Displace native species; reduces biodiversity• Usually non-native

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species

Alien ExoticInvasive Non-indigenousImported WeedyIntroduced Non-nativeImmigrant ColonizerNaturalized

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species• Nomenclature based on 3 major colonization concepts

Dispersal: Short Long

1) Invasive plants – What are they?b) Ecological definitions and characterizations

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species• Nomenclature based on 3 major colonization concepts

Dispersal: Short Long

Uniqueness: Common Novel Common Novel

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species• Nomenclature based on 3 major colonization concepts

Dispersal: Short Long

Uniqueness: Common Novel Common Novel

Impact: Small Great Small Great Small Great Small Great

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species• Nomenclature based on 3 major colonization concepts

Dispersal: Short Long

Uniqueness: Common Novel Common Novel

Impact: Small Great Small Great Small Great Small Great

• 8 ways to be a colonizer

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species• Nomenclature based on 3 major colonization concepts

Dispersal: Short Long

Uniqueness: Common Novel Common Novel

Impact: Small Great Small Great Small Great Small Great

SC SC SC SC

• 8 ways to be a colonizerSC = successional colonizers

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species• Nomenclature based on 3 major colonization concepts

Dispersal: Short Long

Uniqueness: Common Novel Common Novel

Impact: Small Great Small Great Small Great Small Great

SC SC NNC SC SC NNC

• 8 ways to be a colonizerSC = successional colonizersNNC = novel, noninvasive colonizers

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species• Nomenclature based on 3 major colonization concepts

Dispersal: Short Long

Uniqueness: Common Novel Common Novel

Impact: Small Great Small Great Small Great Small Great

SC SC NNC NIC SC SC NNC NIC

• 8 ways to be a colonizerSC = successional colonizersNNC = novel, noninvasive colonizersNIC = novel, invasive colonizers

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature Conservancy

Davis & Thompson (2000)• Ecologists have used different words for invasive species• Nomenclature based on 3 major colonization concepts

Dispersal: Short Long

Uniqueness: Common Novel Common Novel

Impact: Small Great Small Great Small Great Small Great

SC SC NNC NIC SC SC NNC NIC

• 8 ways to be a colonizer, but only 2 ways to be an invaderSC = successional colonizersNNC = novel, noninvasive colonizersNIC = novel, invasive colonizers

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000) Naturalization and invasion of alien plants: concepts and definitions. Diversity and Distributions 6:93-107 (assigned reading)

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)

Processes and barriers

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)ProcessIntroduction

Home range

Introducedarea

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)Process BarrierIntroduction Geographic

Home range

Introducedarea

Geographic

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)Process Barrier If successfulIntroduction Geographic Alien

Home range

Introducedarea

Geographic

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)Process Barrier If successfulIntroduction Geographic AlienNaturalization Environmental Casual

Home range

Introducedarea

Geographic

Environment

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)Process Barrier If successfulIntroduction Geographic AlienNaturalization Environmental Casual

Reproductive Naturalized

Home range

Introducedarea

Geographic

ReproduceEnvironment

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)Process Barrier If successfulIntroduction Geographic AlienNaturalization Environmental Casual

Reproductive NaturalizedInvasion Dispersal Invasive

Home range

Introducedarea

Disturbedarea

Naturalarea

Geographic

ReproduceEnvironment

Disperse

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)

o typically >100 km or past a known geographic barrier

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidence

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidenceHistorical evidence

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidenceHistorical evidenceHabitat

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidenceHistorical evidenceHabitatGeographic distribution

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidenceHistorical evidenceHabitatGeographic distributionFrequency of naturalization

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidence Genetic diversityHistorical evidenceHabitatGeographic distributionFrequency of naturalization

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidence Genetic diversityHistorical evidence Reproductive patternHabitatGeographic distributionFrequency of naturalization

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidence Genetic diversityHistorical evidence Reproductive patternHabitat Possible means of

introductionGeographic distributionFrequency of naturalization

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plants = plant taxa in a given area whose presence is due to

intentional or accidental introduction as a result of human activity

How determine?• Disjunct geographic range (Richardson et al.)• 9 types of evidence (Schwartz in Luken & Thieret 1997)

Fossil evidence Genetic diversityHistorical evidence Reproductive patternHabitat Possible means of

introductionGeographic distribution Oligophagous insectsFrequency of naturalization

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plantsCasual alien plants = alien plants that flourish (and even occasionally

reproduce), but do not form self-replacing populations. Continued presence depends on re-introductions.

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plantsCasual alien plantsNaturalized plants = alien plants that reproduce consistently and

sustain populations over many life cycles without direct intervention by humans

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plantsCasual alien plantsNaturalized plantsInvasive plants = naturalized plants that produce reproductive

offspring (often in large numbers) at considerable distance from parent plants

>100m & <50 years for seed dispersing species>6 m & >3 years for vegetatively reproducing species

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plantsCasual alien plantsNaturalized plantsInvasive plants

Increasing level ofreproductive success

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plantsCasual alien plantsNaturalized plantsInvasive plants

Weeds = plants that grow in sites where they are not wanted; usually have economic or environmental effects

Increasing level ofreproductive success

1) Invasive plants – What are they?b) Ecological definitions and characterizations

NV Coordinated Invasive Weed Strategy Nature ConservancyDavis & Thompson (2000)

Richardson et al. (2000)• Processes and barriers• DefinitionsAlien plantsCasual alien plantsNaturalized plantsInvasive plants

WeedsTransformers = subset of invasive plants that change ecosystems

Increasing level ofreproductive success

1) Invasive plants – What are they?a) State and Federal laws and regulations

Important from legal perspective

b) Ecological definitions and characterizationsImportant for understanding the ecological processes and

consequently, how to prevent and control invasions