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I ♥ Weeds and People Master’s degree in Social Science,
Interdisciplinary at SFSU. Thesis at Pearson-Arastradero Preserve
and employment at Acterra. Experiment with one method of controlling
hemlock on the preserve GIS mapping and data review Literature analysis and program
recommendations about volunteerism
THE STUDYSection 1
Invasive Species 50,000 alien species have invaded the
US.¹ Estimated cost to US: $137 billion/year.² Second most powerful threat to
biodiversity worldwide. ² HIPPO
H = Habitat Loss and Fragmentation I = Invasive Plants P = Pollution P = Population (human overpopulation) O = Overconsumption
Hemlock biology Can grow 3-10 feet
in one year.
Allelopathy
Density – 595 plants in ½ M²
Grows in shady, moist areas.
Produces 5,000 to 38,000 seeds per plant.
Pearson-Arastradero Preserve CA floristic province –
2120 / 3500 vascular plants are endemic.³
247 ha supports 334 species.
Concerns: Invasive plants, recreation impacts.
Contiguity + urbanization = high habitat value.
Related Research Replanting
Oversowing with biologically similar natives (Simmons)4
Effective competitors (Dukes)5
Alellopathy Andrews6: Early
growth and senescing is worst.
Recommends fall/winter removal, re-sow with native grass seed
Site selection 2007 populations of Conium were GPS’d to
compare with 2001 maps. Four areas were selected for: ease of
access, over 75% hemlock coverage, relevancy to Acterra’s work, and volunteer safety.
49 ½ m² quadrats, monitor for 15 months Randomized quadrat locations and
treatments.
Plot locations
Study Design
Hand-pull and re-seed with native plants of similar biology. Elymus glaucus - Blue Wild Rye
Perennial native bunchgrass, can be found in shady areas.
Achillea millefolia –Yarrow Grows near hemlock, prolific, mid-summer seed.
Hemizonia congesta ssp. Luzulifolia - Hayfield tarweed
Late summer seed, forms dense stands.
Originally 5 treatments: Control, pull, replant grass, replant forbs, replant mix.
Results Pre-treatment Conium counts varied from
35 plants per quadrat to 700. High plot attrition. No statistically significant difference
between any of the treatments and the control. No statistically significant correlation found for
Conium maculatum regrowth and: Soil moisture Canopy % or canopy species Slope or aspect Ecotype or plant associates
0.51.01.52.02.53.03.5
TREATMENT
Control Pull Reseed
Treatment Variable
0
100
200
300
400
500
600
Plan
t Cou
nt
Control Pull Reseed
Treatment Variable
0
100
200
300
400
Plan
t Cou
nt
January, 2007Pre-treatment
March, 200815 months after treatment
Graph of results
Recommendations Larger quadrat size – entire plot area instead
of quadrats. Natural boundary, no seed rain. Live plants, not seed. Large size (G), not
plugs. Different plants – shade loving,
rhizotomatous. Baccharis douglasii – Marsh baccharis Heracleum lantanum – Cow parsnip Leymus triticoides – Wet meadow rye Rubus ursinus – CA blackberry Anything you see growing interspersed with
hemlock. Research sites AWAY from restoration areas.
MAPPINGSection 2
Observations Hemlock has
increased in quantity and spread to new areas since 2001.
Spread has primarily occurred along trails and waterways.
Photo by David Smernoff
Recommendations Mapping protocols. Focus on seed-
head clipping and other trailside control work.
Share info at interp. and volunteer events.
Signage, outreach to recreation users. Consider signs at
infestation site / trails.
Photo by Richard Bicknell
VOLUNTEERSSection 3
Background 26 % of US - 61 million people a year6
Why people volunteer (Measham and Barnett)7
Helping a cause Social interaction Improving skills Learning about the
environment General desire to care
for the environment Desire to care for a
particular place
Program planning Integrated educational
component Games, acronyms, audience
participation Skill-building
Project-specific: plant ID, clinometer, research methodology
Program-wide: Educational materials, combined interpretive focus with volunteer work days
Teamwork, meet new people Sense of place: “You are the
stewards of this land.” Biocultural diversity.
Biocultural diversity = Life + Culture + Difference
Connection between Native American cultural areas and ecological niches.8
2124 of CA’s endemic plants overlapped geographically with 14 language families and dialects of 72 endemic Native languages.9
Diverse peoples = Diverse ecologies?
Implications Cocks (2006):
Learn dynamics of various groups’ biocultural values (focus on recreation, resource use, etc.)
Use those as starting points for building additional approaches towards community based conservation.
Results and RecommendationsResults Volunteer participation
rose sharply 750 – 1350.
Participants demonstrated knowledge acquisition & satisfaction with experience.
Increased community participation builds future support base.
Recommendations Program planning -
continue satisfying Measham and Barnett’s six factors
Without essentializing individuals, integrate a biocultural approach into Stewardship work.
Acknowledgements This is a community and collaborative
success. The 2007-08 ASP team: Verna Kirkendall, Claire
Elliott, Sheri Lubin, Deanna Giuliano, and other Acterra folk provided invaluable support and assistance.
Maps are courtesy of Paulo Philippides. Cyrus Hiatt also helped with mapping and data management.
Christine Zable counted about a million hemlock plants.
Tom Cochrane provided plant ID help throughout.
The Rangers were awesome, as usual. Thank you to all the volunteers, friends, family,
colleagues, professors, fellow students, and everyone else who helped.
References 1. Pimentel, D., Zuniga, R., and Morrison, D. (2004). Update on Environmental and
Economic Costs Associated with Alien-Invasive Species in the United States. Ecological Economics, Vol. 52, pp. 278-288.
2. Wilson, Edward O. 2002. The Future of Life. Random House, New York, New York. 229 p.
3. Conservation International (2006). California Floristic Province. Retrieved May 8, 2006 from http://www.biodiversityhotspots.org/xp/Hotspots/california_floristic/
biodiversity.xml. 4. Simmons, M. (2005). Bullying the Bullies; The Selective Control of an Exotic,
Invasive Annual (Rapistrum rugosum) by Oversowing with a Competitive Native Species.
Restoration Ecology, Vol. 13, pp. 609-615. 5. Dukes, Jeffrey. (2001). Biodiversity and Invasibility in Grassland Microcosms. Oecologia, Vol 126, pp. 563 - 568. 6. United States Department of Labor, Bureau of Labor Statistics (2008).
Volunteering in the United States, 2008. Economic news release retrieved May 21, 2009 from http://www.bls.gov/news.release/volun.nr0.htm.
7. Measham, Thomas B. and Barnett, Guy B. (2007). Environmental volunteering: motivations, modes and outcomes. Socio-economics and the environment in discussion : CSIRO working paper series; 2007-03. 30 p.
8. Kroeber (1963) cited in Maffi, Luisa, (2005). Linguistic, cultural, and biological diversity. Annual Review of Anthropology, Vol. 34, pp. 599-617.
References 9. Chung, Eugene R. (2000). Biocultural Diversity Hotspots and GIS Analysis: Alta
California as a Case Study. Abstract. Presented at the 2000 Annual Meeting of the Society for Economic Botany. Retrieved 05/25/07 from: www.econbot.org/_organization_/07_annual_meetings/meetings_by_year/2000/abstracts_2000.pdf.
10. Cocks, Michelle (2006). Biocultural Diversity: Moving Beyond the Realm of 'Indigenous' and 'Local' People. Human Ecology, Vol. 34, pp. 185 - 200.