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![Page 1: Impacts Ecological](https://reader035.fdocuments.in/reader035/viewer/2022062421/56812ad8550346895d8ebb09/html5/thumbnails/1.jpg)
4) Impactsa) Ecological
Conceptual model: From Walker & Smith in Lukens & Thieret (1997)• Invasive species affect:
Nutrient & water availability
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4) Impactsa) Ecological
Conceptual model: From Walker & Smith in Lukens & Thieret (1997)• Invasive species affect:
Nutrient & water availabilityPrimary productivity
![Page 3: Impacts Ecological](https://reader035.fdocuments.in/reader035/viewer/2022062421/56812ad8550346895d8ebb09/html5/thumbnails/3.jpg)
4) Impactsa) Ecological
Conceptual model: From Walker & Smith in Lukens & Thieret (1997)• Invasive species affect:
Nutrient & water availabilityPrimary productivityDisturbance regimes
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4) Impactsa) Ecological
Conceptual model: From Walker & Smith in Lukens & Thieret (1997)• Invasive species affect:
Nutrient & water availabilityPrimary productivityDisturbance regimesCommunity dynamics
![Page 5: Impacts Ecological](https://reader035.fdocuments.in/reader035/viewer/2022062421/56812ad8550346895d8ebb09/html5/thumbnails/5.jpg)
3) Impactsa) Ecological
i) Species replacement• Direct competition From Sherer-Lorenzen in Mooney & Hobbs
(2000)Moist, nutrient rich, disturbed sites in central Europe
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3) Impactsa) Ecological
i) Species replacement• Direct competition From Sherer-
Lorenzen in Mooney & Hobbs (2000)Moist, nutrient rich, disturbed
sites in central EuropeTypically dominated by native
herb Urtica dioica (stinging nettle)
Helianthus tuberosus (Jerusalem artichoke) invading
Urtica (native)Helianthus (invasive)
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3) Impactsa) Ecological
i) Species replacement• Direct competition From Sherer-
Lorenzen in Mooney & Hobbs (2000)Moist, nutrient rich, disturbed
sites in central EuropeTypically dominated by native herb
Urtica dioica (stinging nettle)Helianthus tuberosus (Jerusalem
artichoke) invadingHelianthus undermines and
outshades Urtica, displacing it
Urtica (native)Helianthus (invasive)
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002) Ecological Applications 12:1434-14443 coastal habitats in SF Bay AreaInvasive = Delairea odorata (Cape
ivy) evergreen vine native to South Africa
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002)Cape ivy invading coastal habitatsDecreases species richness for
natives (36%)
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002)Cape ivy invading coastal habitatsDecreases species richness for
natives & non-natives (37%)
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002)Cape ivy invading coastal habitatsDecreases species richness for
natives & non-natives and species diversity (31%)
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002) Cape ivy invading coastal habitatsFewer native & non-native speciesDecreases occur across all habitat
types
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002)Cape ivy invading coastal habitatsFewer native & non-native species
across all habitats and for all plant life forms
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002)Cape ivy invading coastal habitatsFewer native & non-native speciesExperimentally removed Cape ivy:
Control = no removalDisturbance = insert pitchfork
into soil to simulate soil disturbance that accompanies plant removal
Reduction = hand weeded Cape ivy
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002)Cape ivy invading coastal habitatsFewer native & non-native speciesExperimentally removed Cape ivy:
Natives richness ↑ (10%)
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002) Cape ivy invading coastal habitatsFewer native & non-native speciesExperimentally removed Cape ivy:
Natives richness ↑ (10%)Non-natives richness ↑ (43%)
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002)Cape ivy invading coastal habitatsFewer native & non-native speciesExperimentally removed Cape ivy:
Natives richness ↑ (10%)Non-natives richness ↑ (43%)Diversity ↑ (32%)
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements
From Alvarez & Cushman (2002)Cape ivy invading coastal habitatsFewer native & non-native speciesExperimentally removed Cape ivy:
Other species recover,especially forbs (other life
forms NS)
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors
From D’Antonio et al. (2000) Austral Ecology 25: 507-522Series of 14 study sites (#’s) from eastern coastal lowlands to
seasonal submontane zone on Big Island, Hawaii
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors
From D’Antonio et al. (2000)Series of 14 study sites (#’s) from eastern coastal lowlands to
seasonal submontane zone on Big Island, HawaiiLowlands: warm tropical zone with 1500-2000 mm yr-1, but dry
summers; elevation from sea level to 400 mSubmontane: several °C cooler, but similar amount and
seasonality of precipitation; 400 – 1200 m elevation
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors
From D’Antonio et al. (2000)Series of 14 study sites (#’s) from eastern coastal lowlands to
seasonal submontane zone on Big Island, HawaiiLowlands: warm tropical zone with 1500-2000 mm yr-1, but dry
summers; elevation from sea level to 400 mSubmontane: several °C cooler, but similar amount and seasonality
of precipitation; 400 – 1200 m elevationIn both zones, fires occur; most ignited by lava or by humansDo fires consistently favor invasives across this elevational
gradient?
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Measured cover of native species
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Measured cover of native and exotic species
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Measured cover of native and exotic species in adjacent
unburned
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Measured cover of native and exotic species in adjacent
unburned and burned sites along gradient
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Measured cover of native and exotic species in adjacent
unburned and burned sites along gradient
Indi
vidu
al s
ites
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?For seasonal submontane:
For 26 of 35 (74%) occurrences, native had ↓ cover in burned areas
Indi
vidu
al s
ites
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?For seasonal submontane:
For 26 of 35 (74%) occurrences, native had ↓ cover in burned areas
For 28 of 41 (68%) occurrences, exotics had ↑ cover
Indi
vidu
al s
ites
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Submontane: Many natives ↓ & many exotics ↑ with fire
Indi
vidu
al s
ites
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Submontane: Many natives ↓ & many exotics ↑ with fireFor coastal lowlands:
14 of 26 (54%) natives ↓6 of 29 (29%) of exotics ↑
Indi
vidu
al s
ites
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Submontane: Many natives ↓ & many exotics ↑ with fireLowlands: Fewer natives ↓ & fewer exotics ↑ with fire
Indi
vidu
al s
ites
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Yes, but not uniformly
Indi
vidu
al s
ites
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3) Impactsa) Ecological
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Yes, but not uniformlyNot due to differences in rainfall amount or seasonality
Indi
vidu
al s
ites
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3) Impactsa) Ecological
Indi
vidu
al s
ites
i) Species replacement• Direct competition• Large scale species displacements• Interacting factors From D’Antonio et al. (2000)
Do fires favor invasives across elevational gradient?Yes, but not uniformlyNot due to differences in rainfall amount or seasonalityAppears to be due to differences in native species
composition: some of the species in coastal lowlands appear to be fire tolerant
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview
From Walker & Smith in Lukens & Thieret (1997)
Summarized: Typical effects of invasive on specific processes
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview
From Walker & Smith in Lukens & Thieret (1997)
Summarized: Typical effects of invasive on specific processesAnd how this change on a specific process then feeds back and affects community function or structure
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview
From Walker & Smith in Lukens & Thieret (1997)
Summarized: Typical effects of invasive on specific processesAnd how this change on a specific process then feeds back and affects community function or structure
![Page 38: Impacts Ecological](https://reader035.fdocuments.in/reader035/viewer/2022062421/56812ad8550346895d8ebb09/html5/thumbnails/38.jpg)
3) Impactsa) Ecological
ii) Ecosystem functions• Overview
From Walker & Smith in Lukens & Thieret (1997)
Summarized: Typical effects of invasive on specific processesAnd how this change on a specific process then feeds back and affects community function or structure
![Page 39: Impacts Ecological](https://reader035.fdocuments.in/reader035/viewer/2022062421/56812ad8550346895d8ebb09/html5/thumbnails/39.jpg)
3) Impactsa) Ecological
ii) Ecosystem functions• Overview
From Walker & Smith in Lukens & Thieret (1997)
Summarized: Typical effects of invasive on specific processesAnd how this change on a specific process then feeds back and affects community function or structure
![Page 40: Impacts Ecological](https://reader035.fdocuments.in/reader035/viewer/2022062421/56812ad8550346895d8ebb09/html5/thumbnails/40.jpg)
3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Ecosystem C storage
From Jackson et al. (2002) Nature 418:623-626Woody plant invasion into grasslands thought to increase
amount of C storedIf so, then woody plant invasions are good for C sequestration
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Ecosystem C storage
From Jackson et al. (2002)Does woody plant invasion increase C sequestration?Examined 6 sites along precipitation gradient (200 – 1100 mm)
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Ecosystem C storage
From Jackson et al. (2002)Does woody plant invasion increase C sequestration?Examined 6 sites along precipitation gradient (200 – 1100 mm)
that had similar age of woody plant invasion
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Ecosystem C storage
From Jackson et al. (2002)Does woody plant invasion increase C sequestration?Sites along precipitation gradientMeasured total soil organic carbon
in soil profileCalculated total soil organic C for
0-3 m depth for both grass &invaded sites
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Ecosystem C storage
From Jackson et al. (2002)Does woody plant invasion increase C sequestration?Sites along precipitation gradientPlot proportion of total soil organic C
in woody invaded / grass(>1 means more SOC in woody)
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Ecosystem C storage
From Jackson et al. (2002)Does woody plant invasion increase C sequestration?Sites along precipitation gradientPlot proportion of total soil organic C
in woody invaded / grassvs. precipitation
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Ecosystem C storage
From Jackson et al. (2002)Does woody plant invasion increase C sequestration?
Contrary to expectations, ↑ onlyfor dry sites
As precipitation ↑, get less SOCin woody invaded areas
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Soil N change
From Vitousek & Walker (1989) Ecological Monographs 59:247-265Myrica faya small evergreen tree native to Canary Islands &
other islands in North Atlantic OceanActinorhizal N-fixerBrought to Hawaii, where is invading young lava flows that
had been dominated by natives
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Soil N change
From Vitousek & Walker (1989)Exotic Myrica faya, actinorhizal N-fixer, greatly ↑ annual N
input into young lava flows
>
>
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific example: Soil N change
From Vitousek & Walker (1989)Exotic Myrica faya, actinorhizal N-fixer, greatly ↑ annual N
input into young lava flowsHigh N facilitates the invasion of other exotic plants
>
>
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific examples: Fire effects
From D’Antonio in Mooney & Hobbs (2002)Compiled 20 examples from around the world where invaders
have altered fire regimes
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific examples: Fire effects
From D’Antonio in Mooney & Hobbs (2002)20 examples where invaders have altered fire regimesMajority involve perennial grasses (13 of 20 = 65%)
4 (20%) involve annual grasses – All are in arid WestOther 3 are trees / shrubs (Florida, South Africa)
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific examples: Fire effects
From D’Antonio in Mooney & Hobbs (2002)20 examples where invaders have altered fire regimesMajority involve perennial grasses (13 of 20 = 65%)
4 (20%) involve annual grasses – All are in arid WestOther 3 are trees / shrubs (Florida, South Africa)
Majority of invaders represent new life form (14 of 20 = 70%)
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific examples: Fire effects
From D’Antonio in Mooney & Hobbs (2002)20 examples where invaders have altered fire regimesMajority involve perennial grasses (13 of 20 = 65%)
4 (20%) involve annual grasses – All are in arid WestOther 3 are trees / shrubs (Florida, South Africa)
Majority of invaders represent new life form (14 of 20 = 70%)Majority ↑ fire frequency (14; 70%)
Only 2 (10%) ↓ frequency
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific examples: Fire effects
From D’Antonio in Mooney & Hobbs (2002)20 examples where invaders have altered fire regimesMajority involve perennial grasses (13 of 20 = 65%)
4 (20%) involve annual grasses – All are in arid WestOther 3 are trees / shrubs (Florida, South Africa)
Majority of invaders represent new life form (14 of 20 = 70%)Majority ↑ fire frequency (14; 70%)
Only 2 (10%) ↓ frequencyMajority ↑ fire size or intensity (11; 55%)
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3) Impactsa) Ecological
ii) Ecosystem functions• Overview• Specific examples: General compilation
From Crooks (2002)
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3) Impactsa) Ecological
iii) Threatened & endangered species• Overview
~400 of 958 federally listed species (~42%) are because of invasives (includes plants plus other organisms)
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3) Impactsa) Ecological
iii) Threatened & endangered species• Overview
~42% are because of invasivesEffects can be by:
Direct species replacementIndirect through effects on community structure or function
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3) Impactsa) Ecological
iii) Threatened & endangered species• Overview• Specific examples: King Ranch bluestem
Bothriochloa ischaemum (Caucasian bluestem) brought in to southern Great Plains (NM, OK, TX) from Russia in 1929
C4 perennial bunchgrass:establishes readily from seedlong growing seasontolerates heavy grazingfair forage qualityforms dense sod in mature pastures
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3) Impactsa) Ecological
iii) Threatened & endangered species• Overview• Specific examples: King Ranch bluestem
Bothriochloa ischaemum (Caucasian bluestem) brought in to southern Great Plains (NM, OK, TX) from Russia in 1929
C4 perennial bunchgrass: desirable forage speciesSeeded extensively (for example, ~2 million acres in western
OK)
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3) Impactsa) Ecological
iii) Threatened & endangered species• Overview• Specific examples: King Ranch bluestem
Bothriochloa ischaemum (Caucasian bluestem) brought in to southern Great Plains (NM, OK, TX) from Russia in 1929
C4 perennial bunchgrass: desirable forage speciesSeeded extensivelyBut extremely invasive:
Spread along highways into native areas (cemetaries, native grasslands)
Difficult to controlThreatens federally listed endangered plant Ambrosia
cheiranthefolia (south Texas ambrosia)
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3) Impactsa) Ecological
iii) Threatened & endangered species• Overview• Specific examples: Hawaii
80-90 native plant species extinct270 plant species listed as threatened or endangered
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3) Impactsa) Ecological
Summary• Only a small percentage (0.1%) of introduced plants become a
problem
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3) Impactsa) Ecological
Summary• Only a small percentage (0.1%) of introduced plants become a
problem• Ecological impacts typically involve: (1) nutrients/water flow; (2)
primary production impacts; (3) alterations of disturbance regimes; and (4) changes in community dynamics
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3) Impactsa) Ecological
Summary• Only a small percentage (0.1%) of introduced plants become a
problem• Ecological impacts typically involve: (1) nutrients/water flow; (2)
primary production impacts; (3) alterations of disturbance regimes; and (4) changes in community dynamics
• Effects observed as:Species replacements (direct/individual or large scale, w/ or
w/o interactions with other factors such as fire)
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3) Impactsa) Ecological
Summary• Only a small percentage (0.1%) of introduced plants become a
problem• Ecological impacts typically involve: (1) nutrients/water flow; (2)
primary production impacts; (3) alterations of disturbance regimes; and (4) changes in community dynamics
• Effects observed as:Species replacements (direct/individual or large scale, w/ or w/o
interactions with other factors such as fire)Ecosystem functions (C sequestration, N fixation, fire
frequency/intensity)
![Page 66: Impacts Ecological](https://reader035.fdocuments.in/reader035/viewer/2022062421/56812ad8550346895d8ebb09/html5/thumbnails/66.jpg)
3) Impactsa) Ecological
Summary• Only a small percentage (0.1%) of introduced plants become a
problem• Ecological impacts typically involve: (1) nutrients/water flow; (2)
primary production impacts; (3) alterations of disturbance regimes; and (4) changes in community dynamics
• Effects observed as:Species replacements (direct/individual or large scale, w/ or w/o
interactions with other factors such as fire)Ecosystem functions (C sequestration, N fixation, fire
frequency/intensity)Complete or nearly complete loss of native species
(threatened or endangered species)