Privet Hedges as Tree Refuges and Incubators

UEI Summer 2012Mark Gomez, Erin Hall, Carmen Lopes,

Vicente Perez, Dr. Morimoto, et Al.

Introduction

• Question: How does privet hedge size influence the distribution and abundance of trees?

• Useso Green Fence Privacyo Trimmed to any size

What is a privet hedge?o Evergreen, Genus: Ligustrum

Introduction

• Purpose: Are species area relationships maintained in an urban setting (neighborhood scale)?

• Urban Ecologyo Human impact on urban flora

Native population

Habitat restoration• Landscape Ecology

o Using landscaping to promote populations and diversity

Species richness and promote native populations• Species richness while human footprint

Introduction

• McArthur and Wilson(1967) o Island biogeography= isolation and size effectso Habitat fragmentation o Conservation applications

• Hedge Rows and Arthrop0ds(Asia, Europe, Africa, U.S.)o Hedgerows associated with species richness and

individual #'s• Hedge Rows and Aves (England)

o Hedgerow abundance = European starling & House Sparrow

• Hedgerows = Species/ Individuals/ Populations

UNDERSTANDING SPECIES RELATIONSHIPS & PHENOMENON FROM AN URBAN ECOLOGICAL

CONTEXT(URBANIZATION)

• OVER 75% OF U.S. POPULATION NOW LIVES IN A MAJOR METROPOLITAN AREA

• OVER HALF OF THE WORLD'S POPULATION LIVES IN CITIES

Significance of Study

IMPORTANCE OF CONDUCTING AUTHENTIC FIELD STUDIES

• SOUND SCIENCE (EXPERIENCING AND CONNECTING WITH PHENOMENON THRU

OBSERVATIONS) • ENGAGING STUDENTS: EXPLORATION OF

IMMEDIATE SURROUNDINGS• BUILDING STEM SKILLS WITH STUDENTS

Significance of Study:Educational Perspective

Methodology

• Two different neigborhoods: Agassiz 8 & 9o 3 different sections: N/S (Agassiz 8), W (Agassiz 9)

• 31 hedgeso Requirements: No fence, no landscaping o Measured: Maintenance, mulching, volume, area

• 3 days, 50+ person/hrs

Methodology

• Maintenance Types =1(High), 2, & 3(Minimal)

1 2 3

Tree species accumulation curve for the 31 privet hedges sampled in Cambridge,

MA

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 310

2

4

6

8

10

12

14

16

18

20

Cumulative number of treespecies

Privet hedges sampled

Privet Hedge # Individual Trees X Hedge Area (m2)

0 10 20 30 40 50 60 70 800

10

20

30

40

50

60

70

80

# individual treesin a hedge

Privet Hedge area (m2)

mean=13.77 sd=16.02

R=0.77P<0.001df=29

Privet Hedge # Individual Trees X Hedge Volume (m3)

# individual treesin a hedge

Privet Hedge volume (m3)

mean=13.77 sd=16.02

R=0.79P<0.001df=29

0 20 40 60 80 100 120 1400

10

20

30

40

50

60

70

80

Privet Hedge # Tree Species X Hedge Area (m2)

0 10 20 30 40 50 60 70 800

1

2

3

4

5

6

7

Privet Hedge area (m2)

# tree speciesin a hedge

mean=3.10 sd=1.84

R=0.37P=0.038df=29

Privet Hedge # Tree Species X Hedge Volume

(m3)

Privet Hedge volume (m3)

# tree speciesin a hedge

mean=3.10 sd=1.84

R=0.33P=0.033df=29

0 20 40 60 80 100 120 1400

1

2

3

4

5

6

7

Tree species abundance in 31 Cambridge Privet

hedges

NM PO BL PM RM EL AP BA SM QA TH BC HC EH CB SB BW BO MU0

20

40

60

80

100

120

140

160

180

# individuals

Tree species

Tree species frequencies in 31 Cambridge Privet hedges

NM PO RM PM EL BL BA SM CB TH BC AP SB QA HC BW BO MU EH0

5

10

15

20

25

Tree species

# hedges occurred in

High Frequency Trees

• THERE IS THE STRONGEST CORRELATION BETWEEN HEDGE VOLUME AND NUMBER OF TREES.

• A VARIETY OF FACTORS CONTRIBUTED TO THE CLUSTER FORMATION ON THE GRAPHS.

• Human factors such as mulching, pruning, raking underneath hedge and intentional plantings underneath or behind privet hedges affected the data.

• Seed travel from parent within a geographic area by wind or animal also affected the data.

Discussion

Discussion Continued

Community Similarity data analysis (ANOVA) showed that the West Area was the least similar to itself and the other areas (see Map)

• Renting vs. Owning (Private Residences, Apartment buildings, Institutional ownership, etc.)

• Community Associations• Affluence

Discussion End

The diversity profile of a disturbed environment matches the data we found in this urban environment. In a disturbed environment (such as one affected by wildfire) there is an overabundance of a few species. This urban environment is regularly disturbed by human landscaping.

Previous Studies Supporting Privet Hedge Exploration

• Map of Privet Hedge Study through Urban Ecology Institute Summer 2012

• “Luxury effect”- (Hope, Gries, Zhu, F. Fagan, L. Redman, B. Grimm, L. Nelson , Martin, and Kinzig, 2002)∥

• Socioeconomic vs. Plant diversity

• Privets in forest - (Merriam, and Feil, 2002)• Privet decrease # of individuals and # of species in N.C. forest

• Privet type vs. diversity and richness along crop-fields– (Boutin, Jobin, Belanger, and Choiniere, 2002)

• Natural Hedgerows → ↑Diversity, Planted Hedgerows → ↑Richness: Can. E. Forest