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