university of gothenburguniversity of alberta the effects of edges and trampling intensity on...

University of Gothenburg University of Alberta

The effects of edges and trampling The effects of edges and trampling intensity on vegetation in urban forests intensity on vegetation in urban forests

east of east of Edmonton, Alberta, Canada Edmonton, Alberta, Canada

An honours thesis in Environmental ScienceAn honours thesis in Environmental Science

University of Gothenburg, Göteborg, Sweden

Environmental Sciences Program

University of Alberta, Edmonton, CanadaDepartment of Renewable Resources

Weronica IsakssonWeronica IsakssonMarch 19, 2004March 19, 2004


Outline of this presentationOutline of this presentation

BackgroundBackground Objectives of the studyObjectives of the study Study Area and DesignStudy Area and Design Stated hypothesisStated hypothesis ResultsResults SummarySummary ConclusionsConclusions


BackgroundBackground

Part of the Project for Edge and Trampling Effects Part of the Project for Edge and Trampling Effects (Project ET). (Project ET).

Study 1:Study 1: Performed in Finland by University of Performed in Finland by University of Helsinki. Started in 2002.Helsinki. Started in 2002.

Study 2:Study 2: Performed in 3 urban forests east of Performed in 3 urban forests east of Edmonton by the Department of Renewable Edmonton by the Department of Renewable

Resources Resources at the University of Alberta. Started summer 2003.at the University of Alberta. Started summer 2003. Additional studiesAdditional studies will probably be performed in will probably be performed in

other other countries (and cities).countries (and cities).


Background (cont.)Background (cont.)

Project ET consists of 2 sub-projects with focus onProject ET consists of 2 sub-projects with focus on1.1. Carabid fauna (Dr. Matti Koivula)Carabid fauna (Dr. Matti Koivula)2.2. VegetationVegetation

My honours thesisMy honours thesis Sub-project 2 with focus on vegetation. Sub-project 2 with focus on vegetation.

Data collected once in summer 2003.Data collected once in summer 2003.


Objectives of this studyObjectives of this study

Influence onInfluence on vegetation vegetation structure, structure,

composition and diversity by: composition and diversity by: forest clearing forest clearing human access human access

for recreational use.for recreational use.

Examine effects on forest Examine effects on forest structure, structure,

composition and diversity for:composition and diversity for: distance from edge of distance from edge of

trailheads towards interior trailheads towards interior forest forest

trampling on pathstrampling on paths


DefinitionsDefinitions

Edge Edge Boundary between ecosystems with differentBoundary between ecosystems with different vegetative composition and/or physical vegetative composition and/or physical

structure. structure.

Here defined as: line drawn between outermost Here defined as: line drawn between outermost mature trees at trailheads at an open area.mature trees at trailheads at an open area.

TramplingTrampling Trampling by humans and horsesTrampling by humans and horses

Use of mountain bikesUse of mountain bikes

Mowing and trimming of pathwaysMowing and trimming of pathways


Study areasStudy areas

1.1. Elk Island National ParkElk Island National Park2.2. Strathcona Wilderness CentreStrathcona Wilderness Centre3. Cooking Lake-Blackfoot 3. Cooking Lake-Blackfoot

ProvincialProvincial Recreation AreaRecreation Area 1

32


Regional contextRegional context

Boreal mixed-wood forestBoreal mixed-wood forest

Forest canopy dominated by:Forest canopy dominated by:

trembling aspen trembling aspen (Populus (Populus tremuloides) tremuloides)

balsam poplarbalsam poplar (Populus (Populus balsamifera)balsamifera)


Study sites (20 trails)Study sites (20 trails)

6 trails in Elk Island National Park6 trails in Elk Island National Park 6 trails at Strathcona Wilderness Centre 6 trails at Strathcona Wilderness Centre 8 trails in Cooking Lake-Blackfoot Area8 trails in Cooking Lake-Blackfoot Area

Restrictions for selection of study sites (trails)Restrictions for selection of study sites (trails)

Trails should have open-habitat edge at Trails should have open-habitat edge at trailheads.trailheads.

Trails should be in forest patches with minimum Trails should be in forest patches with minimum diameter of 120 m.diameter of 120 m.

No elevation gradients in the area of the trails.No elevation gradients in the area of the trails.


60 m

Open area

3

0 m

Trailhead

Forest Trail Forest

Forest patch: 120 m

Edge 0 m

15 m

Outline of study siteOutline of study site Positions

On Next Off

path to path path

Dis

tan

ces f

rom

tra

ilh

ead

Sampling plot for vegetation

Open area

Forest patch: 120 m


Trampling intensity (use level)Trampling intensity (use level)

Every trail classified within 3 different Every trail classified within 3 different

use levelsuse levels = current trampling intensities = current trampling intensities

of vegetation on paths.of vegetation on paths.

Use level 1 = low trampling intensity Use level 1 = low trampling intensity Use level 2 = moderate Use level 2 = moderate Use level 3 = highUse level 3 = high


Trail, low trampling intensity

Trail, moderate trampling intensity

Trail, high trampling intensity

Examples of trails with different trampling Examples of trails with different trampling intensities (use levels)intensities (use levels)


Measurements taken inMeasurements taken inevery sampling plot forevery sampling plot forvegetationvegetation

Percentage cover of Percentage cover of understory species, understory species, vascular plants only, vascular plants only, 7 different classes.7 different classes.

Canopy cover north Canopy cover north and south of every and south of every plot. Densiometer usedplot. Densiometer used for measurements.for measurements.

Sample plot:Sample plot: Rectangle, size: 0.5 Rectangle, size: 0.5 mm22

0.5x1 m or 0.25x2 m0.5x1 m or 0.25x2 m


Stated hypotheses IStated hypotheses I

The Vegetation Structure, Composition andThe Vegetation Structure, Composition and

Diversity differ:Diversity differ:

at edge of trailheads compared to distances at edge of trailheads compared to distances from edge along pathway into forest. from edge along pathway into forest.

for different positions relative to the paths.for different positions relative to the paths.

for different trampling intensities (use levels) for different trampling intensities (use levels) of the vegetation on the pathways.of the vegetation on the pathways.


Stated hypothesis II (species composition)Stated hypothesis II (species composition)

Shade-intolerant species + introduced species Shade-intolerant species + introduced species more frequent at edge than along trail into more frequent at edge than along trail into forest.forest.

Shade-intolerant + introduced species more Shade-intolerant + introduced species more frequent on paths than next to and farther off frequent on paths than next to and farther off paths.paths.

Proportion of introduced species increased with Proportion of introduced species increased with increasing trampling intensities.increasing trampling intensities.


Statistical analysis – Response variablesStatistical analysis – Response variables

Canopy cover Canopy cover = average of canopy cover = average of canopy cover north and north and south of every plotsouth of every plot

Understory richnessUnderstory richness = number of vascular = number of vascular plants plants (understory)(understory) species in each plotspecies in each plot

Total understory coverTotal understory cover = addition of = addition of cover cover estimates for all understory species in estimates for all understory species in each ploteach plot

Shannon-Wiener diversity indexShannon-Wiener diversity index (H’) (H’) = = understory diversity,understory diversity, distribution of species distribution of species

among among plots. Low values,plots. Low values, low diversity. low diversity.


Statistical analysis - Model for ANOVAStatistical analysis - Model for ANOVA

Independent variablesIndependent variables LevelsLevelsDegrees of Degrees of freedom freedom (df)(df)

DistanceDistance 44 33

PositionPosition 33 22

Use levelUse level 33 22

Distance * use levelDistance * use level 1212 1111

Distance * positionDistance * position 1212 1111

Position * use levelPosition * use level 99 88

Distance * position *Distance * position *

use leveluse level3636 3535


Results from ANOVA. Results from ANOVA. Test for variations of mean values for response Test for variations of mean values for response

variablesvariables

****** Statistical significance 0.05. Statistical significance 0.05. Variations in mean values of response variables. Variations in mean values of response variables.

Response Response variablesvariables

Distance Distance from from

edge (m)edge (m)

Use Use LevelLevel

PositionPosition SiteSite (Use Level(Use Level*Distance)*Distance)

Canopy Canopy CoverCover

30 ***30 *** 3.5 ***3.5 *** 31 ***31 *** 3.2 ***3.2 ***

Total Under-Total Under-story Coverstory Cover

1.11.1 0.320.32 53 ***53 *** 1.01.0

Understory Understory RichnessRichness

5.6 ***5.6 *** 5.1 ***5.1 *** 84 ***84 *** 2.2 ***2.2 ***

Understory Understory Diversity Diversity (H')(H')

2.8 ***2.8 *** 3.03.0 69 ***69 *** 2.0 ***2.0 ***

The table contains F valuesThe table contains F values


Results of ANOVA.Results of ANOVA.Test for interactions among independent variablesTest for interactions among independent variables

*** *** Statistical significance 0.05.Statistical significance 0.05. Interactions for independent variables. Interactions for independent variables.

Response Response variablesvariables

DistancDistance*e*

Use Use levellevel

PositionPosition**

Use Use levellevel

DistanceDistance**

PositionPosition

Distance * Distance * Position * Position * Use levelUse level

Canopy Canopy CoverCover

9.6 ***9.6 *** 9.8 ***9.8 *** 15 ***15 *** 5.3 ***5.3 ***

Total Total Under-story Under-story CoverCover

2.3 ***2.3 *** 14 ***14 *** 11 ***11 *** 4.3 ***4.3 ***

UnderstoryUnderstoryRichnessRichness

2.4 ***2.4 *** 21 ***21 *** 17 ***17 *** 6.2 ***6.2 ***

Understory Understory Diversity Diversity (H')(H')

1.61.6 17 ***17 *** 13 ***13 *** 4.8 ***4.8 ***

The table contains F valuesThe table contains F values


Variations in mean values of Canopy CoverVariations in mean values of Canopy Cover

Mean of Canopy Cover for Distance and Position

Distance from edge (m)0 10 20 30 40 50 60

Mean

of

can

op

y c

over

(±S

E)

3035404550556065707580

On pathsNext to pathsOff paths

Mean of Canopy Cover for Distance and Use Level

Distance from edge (m)0 10 20 30 40 50 60M

ean

of

can

op

y c

over

(±S

E)

30354045505560657075

Low trampling intensity

Moderate trampling intensity

High trampling intensityTra

ilh

ead

Tra

ilh

ead


Effects of Distance and Position on Total Understory Effects of Distance and Position on Total Understory Cover and Understory Richness Cover and Understory Richness

Mean of Total Understory Cover for Distance and Position

Distance from edge (m)

0 10 20 30 40 50 60

Mean

of

un

ders

tory

cover

(±S

E)

20

30

40

50

60

70

80

90

100

On pathsNext to pathsOff paths

Mean of Understory Richness for Distance and Position

Distance from edge (m)0 10 20 30 40 50 60

Mean

of

un

ders

tory

ric

hn

ess (

±S

E)

4

6

8

10

12

On pathsNext to pathsOff pathsT

railh

ead

Tra

ilh

ead


Effects of Distance and Position on UnderstoryEffects of Distance and Position on UnderstoryDiversity Diversity (H’)(H’)

Mean of Understory Diversity (H’)for Distance and Position

Distance from edge (m)

0 10 20 30 40 50 60

Mean

of

un

ders

tory

div

ers

ity (

±S

E)

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

On pathsNext to pathsOff pathsT

railh

ead


Effects of Position and Use level on Total Understory Effects of Position and Use level on Total Understory Cover and Understory RichnessCover and Understory Richness

Mean of Understory Richness

for Position and Use Level

Position

Mean

of

un

ders

tory

ric

hn

ess (

±S

E)

2

4

6

8

10

12



High trampling intensity

On path Next to path Off path

Mean of Total Understory Cover for Position and Use Level

PositionOn path Next to path Off path

Mean

of

un

ders

tory

cover

(±S

E)

10

20

30

40

50

60

70

80

90

100





Effects of Position and Use level on Understory Effects of Position and Use level on Understory Diversity Diversity (H’)(H’)

Mean of Understory Diversity (H’) for Position and Use Level

PositionOn path Next to path Off path

Mean

of

un

ders

tory

div

ers

ity (

±S

E)

0.40.60.81.01.21.41.61.82.02.2

Low trampling intensityModerate trampling intensity



Ordinations – Understory CompositionOrdinations – Understory Composition

To examine patterns in understory vegetation To examine patterns in understory vegetation

composition in relation to distance, use level and composition in relation to distance, use level and

position.position.

Vegetation plots close to each other in ordination Vegetation plots close to each other in ordination

diagram are similar in species composition.diagram are similar in species composition.

CA (Correspondence Analysis) performed first, CA (Correspondence Analysis) performed first,

inconclusive results. DCA (Detrended CA) used inconclusive results. DCA (Detrended CA) used instead.instead.


On pathNext to pathOff path

DCA Axis 1

0 1 2 3 4 5 6 7

DCA

Axi

s 2

0

1

2

3

4

5

Ordinations (DCA)Ordinations (DCA)

Vegetation plots Vegetation plots (positions)(positions) Axis Axis

11Axis Axis 22

EigenvaluesEigenvalues 0.770.77 0.590.59

Length of Length of gradientgradient

5.85.8 4.24.2

Cumulative Cumulative % variance % variance of species of species datadata

4.94.9 8.78.7

Sum of all Sum of all eigenvalueseigenvalues

15.515.5

Total number of Total number of understory species found: understory species found: 104.104.


Ordinations - Understory CompositionOrdinations - Understory Composition

ResultsResults Different for vegetation plots at positions on Different for vegetation plots at positions on

paths paths

compared to positions next to paths and far off compared to positions next to paths and far off into the forest.into the forest.

No variations in composition for trails with No variations in composition for trails with different trampling intensities (use levels). different trampling intensities (use levels).

No variations in composition for different No variations in composition for different distances from the trailhead along paths into distances from the trailhead along paths into forest.forest.


Perc

en

tag

e o

f fr

eq

uen

tly

occu

rrin

g u

nd

ers

tory

sp

ecie

s

Introduced species

Shade-intolerant herb Shade-intolerant grass Shade-intolerant shrub

Shade-tolerant herb

Shade-tolerant shrub

On path Next to and off path

Ordinations - Understory Composition (cont.)Ordinations - Understory Composition (cont.)

0

10

20

30

40

50

60

Good news:Good news: Next to and off Next to and off paths, no paths, no introduced species introduced species among frequently among frequently occurring species.occurring species.

Understory types frequently occurring on paths versus next to and off paths


Understory species frequently occurring on Understory species frequently occurring on pathspaths

Common name Scientific name Species groups

Awned wheat grass Agropyron trachycaulum Shade-intolerant grass.

Kentucky bluegrass Poa pratensis Shade-intolerant grass.

Hairy wild rye Elymus innovatus Shade-intolerant grass.

Fringed brome Bromus ciliatus Shade-intolerant grass.

Foxtail barley Hordeum jubatum Shade-intolerant grass.

Tufted hair grass Deschampsia caespitosa Shade-intolerant grass.

Wild strawberry Fragaria virginiana Shade-intolerant herb.

Common plantain Plantago major Shade-intolerant herb.

Hemp-nettle Galeopsis tetrahit Shade-intolerant herb.

Alsike clover Trifolium hybridum Shade-intolerant herb.

White clover Trifolium repens Shade-intolerant herb.

Common dandelion Taraxacum officinale Shade-intolerant herb.

False melic Schizachne purpurascens Shade-intolerant herb.

Introduced species in yellow.Introduced species in yellow. Names and groups of species from Johnson Names and groups of species from Johnson et et alal (1995). (1995).


Summary – Outcome of stated hypotheses ISummary – Outcome of stated hypotheses I

The Vegetation Structure, Composition and The Vegetation Structure, Composition and Diversity differ:Diversity differ:

at edge of trailheads compared to increasing at edge of trailheads compared to increasing distances from edge along trail into forest. distances from edge along trail into forest.

for different positions relative to the trail.for different positions relative to the trail.

for different trampling intensities (use levels) for different trampling intensities (use levels) of the vegetation on the trails.of the vegetation on the trails.


Summary – Outcome of stated hypotheses IISummary – Outcome of stated hypotheses II

Species Composition:Species Composition:

Shade-intolerant species + exotic species more Shade-intolerant species + exotic species more

frequent at edge than along trail into forest. frequent at edge than along trail into forest.

Shade-intolerant + exotic species more frequent Shade-intolerant + exotic species more frequent on paths than next to and farther off paths. on paths than next to and farther off paths.

Proportion of exotic species increased with Proportion of exotic species increased with

increasing trampling intensities.increasing trampling intensities.


Conclusions – alleviation of disturbancesConclusions – alleviation of disturbances

Possible remedies:Possible remedies:

Vegetation inventories to identify location of Vegetation inventories to identify location of significant plants. significant plants.

Monitor locations of rare/threatened species. Monitor locations of rare/threatened species.

Protect these locations from disturbance and Protect these locations from disturbance and new new development.development.

Develop facilities for users of horses and Develop facilities for users of horses and mountain bikes to clean away seeds from mountain bikes to clean away seeds from exotic exotic species and decrease the spread of exotic species and decrease the spread of exotic species.species.


Possible remedies:Possible remedies:

Educate users about how to minimize impact of Educate users about how to minimize impact of trampling.trampling.

Frequently monitor trail conditions. Upgrade wet Frequently monitor trail conditions. Upgrade wet parts parts

to decrease trampling effects on soil and to decrease trampling effects on soil and vegetation. vegetation.

Design trails to decrease disturbance on Design trails to decrease disturbance on vegetation:vegetation: Restrict trails to communities most tolerant to Restrict trails to communities most tolerant to trampling and edge effectstrampling and edge effects Close possible access to other evident pathsClose possible access to other evident paths

Plant dense thorny plants, e.g., prickly rose, wild Plant dense thorny plants, e.g., prickly rose, wild raspberryraspberry

close to edge to discourage off-trail excursions into close to edge to discourage off-trail excursions into forest by hikers.forest by hikers.

Conclusions – alleviation of trampling effectsConclusions – alleviation of trampling effects


Conclusions – alleviation of edge Conclusions – alleviation of edge effectseffectsPossible remedies:Possible remedies:

Plant fast growing species along recently Plant fast growing species along recently created created edges to help speed up growth of buffer edges to help speed up growth of buffer vegetation. vegetation.


Further research Further research should be done to should be done to identifyidentify

SpeciesSpecies CommunitiesCommunities Habitats Habitats

that are particularly that are particularly important in the three important in the three study areas. study areas.

Specific studies of impact Specific studies of impact of recreation on these of recreation on these could then be conducted.could then be conducted.


AcknowledgementAcknowledgement

I am grateful to:I am grateful to: Dr. Ellen Macdonald, University of AlbertaDr. Ellen Macdonald, University of Alberta Dr. Matti Koivula, University of AlbertaDr. Matti Koivula, University of Alberta Dr. Göran Dave, University of GothenburgDr. Göran Dave, University of Gothenburg

Study facilities and field work support:Study facilities and field work support: Department of Renewable Resources, University Department of Renewable Resources, University

of Albertaof Alberta

university of gothenburguniversity of alberta the effects of edges and trampling intensity on...

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