Black Cohosh Presence and Abundance Relative to Environmental Gradients

1
Black Cohosh Presence and Abundance Relative to
Environmental Gradients

• Nicole Hupp- Regis University, Denver, Colorado
• Dr. Luben Dimov- Alabama A M University,
  Normal, Alabama
• A National Science Foundation- REU Funded Study
• July 25, 2008

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What is black cohosh?

• Black cohsoh (Actea racemosa) is a hardy
  perennial native to eastern and southeastern
  United States and southern portion of Canada
• Typically found at about 1-3 feet in height
• Contains bolts (flowering structures)
• Strong, distinct odor

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The significance of black cohosh

• Known for its medicinal properties
• Historically used to treat a variety of issues
• Currently used by women in the US and Europe for
  relief from menopausal complaints
• Perhaps a safer alternative to hormone
  replacement therapy

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Study Relevance

• Due to increase in popularity over the last
  decade, value of black cohosh has increased
• Price peaked in 2000 at 14-17/lb. (ASI, 2001)
• Nearly 97 of black cohosh used harvested from
  the wild (Lyke, 2001)
• No quantitative studies on its ecological
  requirements  

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Objectives

• Determine the relationship between
• black cohosh abundance and flowering performance
• environmental variables
• Test hypotheses indicated by other studies
  concerning black cohosh habitat

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Hypotheses

• Black cohosh plot cover is not related to the
  studied environmental variables, including canopy
  cover, tree basal area, stand stocking, and soil
  moisture
• Black cohosh will be found only on northeast
  facing slopes that are well drained and
  significantly shaded

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Site Description

• Plots established in Jack Gap, Jackson County, AL
  (Cumberland Plateau) (34 56' 19.6434" N, 86 5'
  8.0658)
• Located on escarpments of plateau with deep,
  loamy soils that have moderately low fertility
  and are well drained (Smalley, 1982)
• Most slopes range from 15 to 30 percent (Smalley,
  1982)

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Methods

• We used systematic sampling by establishing
  transects along elevation gradient of the plateau
  escarpment
• We selected circular plots (r5 m, plot area78.5
  m2) located at points along transects that
  contained black cohosh
• Locations visible from but
• not on transects were
• studied if we encountered
• black cohosh in them

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Statistical Analysis

• Only basic statistical methods were used up to
  this point
• Reported is only minimum, maximum, mean, standard
  deviation, and preliminary multiple linear
  regression results
• We will carry out more complex analysis with
  multiple linear regression and non-parametric
  ordination

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Dependent Variables

• Black cohosh plot cover
• Number of bolts (flowering structures) on the
  plot

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Environmental Characteristics Studied

• Microtopography
• Soil ph
• Percent soil moisture
• Aspect
• Tree basal area
• Photosynthetically Active Radiation
• Slope
• Canopy cover

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Results

• Only basic statistics reported at this time more
  complex analysis is being performed

  Standard Dev Average Minimum Maximum
Cohosh Cover (m2/plot) 5.65 4.93 0 29
Cohosh Plants/plot 16.61 17.6 0 58
Number Flowering Bolts/plot 5.82 4.24 0 25
Basal Area (ft2/ac) 29.5 103.91 20 170
Percent Open Canopy North 3.12 5.93 1.04 14.56
Percent Open Canopy South 3.81 7.05 4.04 15.6
Percent Open Canopy East 3.92 7.42 1.04 15.6
Percent Open Canopy West 3.22 5.57 1.04 16.64
Total Percent Open Canopy 5.00 7.17 2.6 34.06
Aspect Adjust w/ Beers 0.75 0.74 0.00 2
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Results
Regression with number of bolts as the dependent
variable and aspect as predictor
Regression with cohosh cover as dependent
variable and slope as predictor
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Discussion

• Black cohosh has been previously reported to only
  be found on northeastern facing slope
• We found it to be more of a generalist
• Beneficial knowledge for those wanting to plant
  or harvest black cohosh from the wild

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Future Research

• Further explore relationships between black
  cohosh and environmental characteristics
• Use multiple linear regression
• Consider non-linear relationships and ordination
  techniques to see relationship of predictors and
  amount of cohosh and number of flowering bolts

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Interesting Facts

• On several plots black cohosh was found under
  black walnut despite allelopathic effects
• American chestnut occurrence

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Acknowledgements

• Dr. Luben Dimov
• National Science Foundations REU Grant
• Alabama A M University
• USDA Forest Service
• Regis University
• The State of Alabamas Department of Conservation
  and Natural Resources
• Dawn Lemke
• Lynne Weninegar
• Dr. Yong Wang