Bloodroot (Sanguinaria canadensis L.) Extent and Sustainability in Western North Carolina

doi:10.4236/ojf.2012.24026

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Open Journal of Forestry

2012. Vol.2, No.4, 213-218

Published Online October 2012 in SciRes (http://www.SciRP.org/journal/ojf) http://dx.doi.org/10.4236/ojf.2012.24026

Bloodroot (Sanguinaria canadensis L.) Extent and Sustainability

in Western North Carolina

Jill Furgurson1*, Fred Cubbage2, Erin Sills2, Peter Bates3

1Department of Geography, University of North Carolina, Chapel Hill, USA

2Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, USA

3Department of Geosciences and Natural Resources, Western Carolina University, Cullowhee, USA

Email: *[email protected]

Received June 13th, 2012; revised July 24th, 2012; accepted August 8th, 2012

Bloodroot distribution and abundance were assessed in the Waynesville watershed in Western North

Carolina. This high quality site provides a benchmark for bloodroot populations in the region. Summary

data from an inventory of nine stands of bloodroot in the watershed are presented. Analysis of inventory

data reveals that both petiole height and petiole diameter are negatively associated with overstory tree

DBH, suggesting that there is an optimal overstory structure for bloodroot. In the Waynesville watershed,

seven out of nine stands have an average tree DBH between 27.38 cm and 36.17 cm. Allometric equations

relating belowground biomass to bloodroot petiole height and diameter have strong explanatory power,

indicating that harvesters could selectively harvest large rhizomes by targeting plants with larger petioles.

These results in combination with natural history, field observations and literature provide insights on the

sustainability of bloodroot harvest in Southern Appalachia. Wild bloodroot is likely becoming scarce due

to loss of favorable sites, such as rich cove forests, as well as harvest pressure.

Keywords: Bloodroot; Nontimber Forest Product; NTFP; Sustainability; Waynesville Watershed; Western

North Carolina

Introduction

The forest plant bloodroot (Sanguinaria canadensis L.) is

harvested from natural stands in the eastern United States for

both artistic and medicinal uses. In order to ensure this resource

is available for future generations, baseline information is re-

quired for establishing sustainable harvesting regimes. Density

and size-class structure are essential data for determining sus-

tainable harvest levels for nontimber forest products from natu-

ral forest ecosystems (Peters, 1994). Sustainable, as used in this

study, has both biological and managerial dimensions. Harvests

are sustainable if they allow the continuation of viable natural

populations of the resource and should incorporate management

practices that support indefinite yields. Additional goals include

maintenance of biodiversity within natural stands, preservation

of traditional knowledge, and generation of income for local

communities.

Bloodroot Uses and Sustainability

Bloodroot is an herbaceous perennial plant that grows in rich

well-drained forest soils (Predny & Chamberlain, 2005; Green-

field & Davis, 2004). Populations of the plant can be found

from the Atlantic to the Rocky Mountains, and from southern

Canada through the southern United States (Cech, 2002). In

Western North Carolina, bloodroot is harvested for both me-

dicinal and artistic uses and is currently used by the Eastern

Band of Cherokee Indians as a dye plant for hand woven bas-

kets, a tradition that goes back for hundreds of years. In recent

years the plant has been considered as an alternative to syn-

thetic antibiotics used in cattle feeds (Greenfield & Davis,

2004), and bloodroot alkaloids have been studied as a compo-

nent of cancer treatment medications (Nihal et al., 2000).

Bloodroot is considered to be a nontimber forest product

(NTFP) since nearly all harvesting is from natural stands, as

opposed to cultivated sources. NTFPs are biological resources,

such as medicinal plants, nuts, resins, dyes and ornamental

plants, which can be harvested from the forest to provide in-

come. Despite the widely touted conservation potential of

NTFPs, ecological assessments of harvesting implications are

rare (Ticktin, 2004). NTFPs offer local communities in South-

ern Appalachia a supplemental income from the forest and are

important to local culture, but over-harvesting of wild popula-

tions could pose a threat to long term population viability.

Over-collection is an important factor in population decline

of medicinal plants, and this is especially true of plants where

the root, bark or whole plant is harvested (Hayden, 2005). Since

the rhizome of bloodroot contains the desired medicinal com-

pounds, the plant is especially susceptible to mortality follow-

ing harvesting if careful collection practices are not followed.

Members of the Eastern Band of Cherokee Indians recommend

replanting a piece of the rhizome back into the ground while

harvesting bloodroot in order to maintain viable populations.

This practice is in accordance with recommended propagation

methods, which suggest breaking the rhizome into small pieces,

approximately one to two inches, for successful clonal propaga-

tion (Persons & Davis, 2005).

As Greenfield and Davis (2004) report, increasing demand

for bloodroot is putting pressure on naturally occurring popula-

tions. For centuries, the many uses of bloodroot have led to its

being intensively harvested from North American forests. Al-

*Corresponding author.

J. FURGURSON ET AL.

though small quantities of dried bloodroot from wild stock can

be found on the market, and some nurseries offer small vol-

umes of cultivated stock, large volumes are not available from

cultivated sources (Persons & Davis, 2005). Conventional cul-

tivation of forest medicinal plants can be cost prohibitive,

which is one factor contributing to diminishing wild popula-

tions (Naud et al., 2009). The USDA Forest Service Southern

Research Station (SRS) has recognized an increase in the har-

vesting of special forest products in the southeastern United

States and associated threats to the long-term social, ecological

and economic sustainability of these forest resources (Cham-

berlain, 2004).

The development of a management plan for a medicinal plant

should incorporate knowledge from various sources. The

Cherokee people utilized and influenced forest resources long

before the development of forest science. In order to most ef-

fectively manage forest resources such as bloodroot, collabora-

tion between local communities, government agencies and for-

est scientists is necessary. Understanding traditional knowledge

regarding forest resources is an integral part of developing sus-

tainable management plans. However, consumption patterns

today differ from historical trends, and knowledge of the pre-

sent state of the forest is also important for guiding manage-

ment plans. With a greater demand for forest products, it is

necessary to combine traditional knowledge of distribution and

growth patterns with monitoring efforts and inventory analysis.

Specifically, a forest inventory is necessary to ascertain the

current distribution and abundance of the populations of the

species under consideration (Peters, 1994).

Case Study Overview

We implemented a detailed bloodroot inventory in the

Waynesville city watershed in Haywood County in western

North Carolina. The site was chosen because of its mature for-

ests that provide high-quality sites for bloodroot and because

bloodroot harvest had not been allowed. The strategic man-

agement plan for the watershed has the primary objective of

maintaining a healthy and diverse forest to ensure a supply of

high quality drinking water for the town of Waynesville. The

preservation of unique plant species is a secondary objective,

and although selective timber harvests occasionally occur,

nearly all stands in the bloodroot growth areas contain trees of

approximately 80 - 85 years.

A single resource inventory at one point in time allows quan-

tification of the distribution and abundance of the resource and

estimation of relationships pertinent to sustainable harvesting.

In this case, inventory data on plant sizes and population densi-

ties from the Waynesville watershed in Western North Carolina

are used to establish a baseline on biological supply of blood-

root in natural stands not subject to harvesting. This provides a

reference point useful both for development of guidelines for

sustainable levels of extraction and for assessment of the poten-

tial for this resource to be sustainably utilized. Further, we

combine the data from this site with the literature on forest

types in the Appalachians to estimate the extent of bloodroot in

the region.

We also analyze the relationship between easily recognized

aboveground characteristics (petiole height and petiole diameter)

and belowground biomass of rhizomes. The ability to predict

belowground biomass without actually harvesting the plant is

critical for sustainable harvesting. Specifically, if harvesters can

practice more selective harvesting, plant mortality rates may

decline.

Methods

In the summer of 2006, we canvassed sites with both pro-

tected and harvested stands of bloodroot. We measured the

density of bloodroot and forest stand conditions in both types of

sites and then focused on the 8030 acre tract of mature second

growth forest that comprises the Waynesville watershed (Fig-

ure 1). The Waynesville watershed is a north-facing, rich forest

cove site with trees approximately 80 - 85 years old. It is a high

Figure 1.

Map of location of Waynesville watershed in Western North Carolina.

214

J. FURGURSON ET AL.

quality mature hardwood forest with good soils and drainage,

and provides high quality habitat for bloodroot growth. Situated

within the Great Balsam Mountains/Pisgah Ridge Natural

Heritage Megasite, the watershed is part of a natural heritage

area recognized by the NC Natural Heritage Program (Conser-

vation Trust for North Carolina, 2005).The watershed is man-

aged under a conservation easement that limits timber harvests.

Further, the bloodroot stands in the watershed are considered

protected and not subject to harvesting.

Bloodro ot a nd Forest Sampling

Bloodroot stands were defined as naturally isolated popula-

tions of individual plants geographically separated from other

bloodroot growth areas. Random sampling, which can be time

consuming and leave large sections of an area unsampled, is not

always appropriate for inventories and monitoring of NTFPs

(Kerns et al., 2002). Based on the literature (Predny & Cham-

berlain, 2005; Persons & Davis, 2005), we identified areas

within the watershed likely to support bloodroot growth and

then completely surveyed these areas. The identified areas were

based on forest type and all rich cove, mesic and northern

hardwood stands were sampled. All stands of bloodroot identi-

fied were inventoried to provide a census of bloodroot popula-

tions within the watershed.

The width and length of the identified stands were measured

and then a central transect was created that ran the entire length

of the stand. Petiole height (from the soil surface) and petiole

diameter at ground level were measured for all plants growing

within one half meter of either side of the transect. The total

number of plants measured was 2789. Data were also collected

on species and DBH of overstory trees, as well as stand eleva-

tion.

The analyses of above and belowground biomass relation-

ships were based on 174 plants harvested from the Waynesville

watershed between July 25 and August 4, 2006. Occasionally,

one bloodroot rhizome can support several stems. Since the

intent was to examine the relationship between above ground

leaf characteristics and rhizome mass, only rhizomes supporting

one petiole were measured.

The length and wet weight of rhizomes were measured. Rhi-

zomes were weighed wet so that they could be replanted di-

rectly following measurement. However, the rhizomes are usu-

ally marketed in a dried form.

Statistical Analyses

A one-way analysis of variance (ANOVA) test was per-

formed to detect differences among stands in density of blood-

root (using JMP from SAS). The relationships between the

aboveground plant characteristics of petiole height and diame-

ter and tree dbh were analyzed with ordinary least squares

(OLS) regression analysis, using a robust estimator for cluster-

ing by stand (using LIMDEP). We also estimated OLS regres-

sions of rhizome biomass as a function of petiole height and

petiole diameter to identify relationships between the above-

ground plant characteristics and below ground biomass. Fol-

lowing the methods of Ott and Longnecker (2001), all analyses

were conducted with and without an outlier stand that is excep-

tionally small and that has an exceptionally high density of

bloodroot. We included intercepts in all regressions, as recom-

mended by Bond-Lamberty et al. (2002).

Results

Bloodroot Extent

Bloodroot was found growing on approximately 34.8 acres

(141,445 m2) of the 433 acres (1,752,000 m2) of suitable habitat

cruised on the Waynesville watershed, or about 4.2 percent of

the watershed. The bloodroot was distributed across the water-

shed in nine stands, of which eight are located on northern

hardwood slopes or poplar coves. The ninth stand is located in a

mesic oak-hickory stand. The statistics for the nine bloodroot

stands are summarized in Table 1. The bloodroot stands vary in

dimensions, from 2.2 × 2.4 to 395 × 140 meters. Eight of the

nine stands have a mean area of 17,679 m2, while an outlier

stand has an area of just 5.28 m2. Average bloodroot densities

for the nine stands vary from 1.68 to 35.42 plants per square

meter. These values are based on the density measurements

obtained from sampling along the central transect and are used

for the ANOVA analyses. Eight out of nine of the stands have

average densities of 6.77 plants per square meter or lower. The

small stand with a density of 35.42 plants per square meter is

unusual when compared to all other stands sampled and can-

vassed for this study, and thus is treated as an outlier.

The petiole height of bloodroot plants in the Waynesville

watershed varies from 7.62 cm to 33.02 cm and petiole diame-

ter ranges from 0.08 cm to 0.75 cm. Average petiole heights at

the stand level vary from 13.94 cm to 26.39 cm and average

petiole diameters at the stand level vary from 0.23 cm to 0.40

cm.

The average tree diameter at breast height (DBH) of the

overstory trees measured in each stand varies from 15.27 cm to

31.83 cm. However, 7 out of 9 stands have an average tree dbh

between 27.38 cm and 36.17 cm. Tree species richness, defined

as the number of overstory tree species identified within the

stand, ranges from four to eight species. The most common

species are tulip poplar, red oak, hickory and white oak.

The results of the one way ANOVA revealed that there were

no significant statistical differences (α = 0.05) in mean densities

among the nine bloodroot stands in the Waynesville watershed

(F = 2.583; df = 1.7; p = 0.152), even including the outlier stand.

Excluding the outlier stand, the F statistic drops to 0.092, with a

p value of 0.772.

Average petiole height is significantly negatively correlated

with average tree dbh (coefficientdbh = -1.2, p-value = 0.02, R2

= 0.67, df = 2788). Average petiole diameter is also negatively

correlated with average tree dbh (coefficientdbhl = -0.02, p-value

= 0.05, R2 = 0.34, df = 2788). In stands with larger overstory

trees, bloodroot plants tend to be smaller, whether measured by

petiole height or diameter.

Relationship between Aboveground Form and

Belowground Volume

Site-specific allometric equations were developed relating

the aboveground plant characteristics of petiole height and

petiole diameter to the belowground biomass of rhizomes.

Simple linear regressions of rhizome weight on each of these

characteristics were statistically significant for petiole height,

R2 = 0.65, pmodel < 0.0001 (Figure 2); and for petiole diameter,

R2 = 0.73; pmodel < 0.0001 (Figure 3). Thus, diameter has the

greatest explanatory power.

A single multiple regression was estimated after controlling

for petiole characteristics and confirms that the model continues

J. FURGURSON ET AL.

Table 1.

Bloodroot stand inventory data.

Stand number Average density (plants/m) Average petiole height (cm)Average petiole diameter (cm)Average tree dbh (cm) Count of tree species

1 35.42 26.39 0.40 15.27 5

2 5.99 16.18 0.26 36.17 4

3 2.09 19.61 0.34 27.99 8

4 2.10 18.14 0.29 28.55 5

5 1.68 18.13 0.29 27.38 7

6 6.77 16.33 0.25 27.94 5

7 1.82 16.93 0.26 29.64 8

8 3.31 15.58 0.23 30.12 5

9 5.79 13.94 0.29 31.83 6

0510 15 20 25 30 35 40

Rhi z om e wei g ht ( g)

Petiole height (cm)

Figure 2.

Scatter plot and fitted simple linear regression of bloodroot rhizome weight on stem height,

N = 174, Rhizome weight (g) = -5.1387 + 0.4319 (petiole height); R2 = 0.65; p < 0.0001.

Figure 3.

Scatter plot and fitted simple linear regression of bloodroot rhizome weight on stem diameter,

N = 174, Rhizome weight (g) = -2.9825 + 27.5459 (petiole diameter); R2 = 0.73; p < 0.0001.

to provide a good fit for the data (R2 = 0.77, pmodel < 0.0001),

and the coefficients on both petiole height and diameter re-

mained significant at the 1% level. The allometric equation for

predicting belowground rhizome biomass with only these sta-

tistically significant predictor variables of petiole height and

petiole diameter is:

Rhizome weight (g) = -4.6284 + 0.1802 (petiole height) +

18.7254 (petiole diameter).

Discussion

While nontimber forest products have received increasing

216

J. FURGURSON ET AL.

attention (Shackleton et al., 2011, Kerns et al., 2002, Ticktin,

2004), our research found relatively little literature relating to

their sustainable harvest (Wong, 2000). We did not find any

research recommending guidelines for harvest of bloodroot. In

order to address this gap in the scientific literature, this study

provides plant size and stand density information for nine

stands of protected bloodroot in the Waynesville watershed of

North Carolina. We also analyzed the relationship between

easily observable aboveground plant characteristics and below-

ground biomass, which could contribute to guidelines for sus-

tainable harvest of the resource. In this section, we complement

the analyses with a brief discussion of the distribution and long

term sustainability of bloodroot in western North Carolina to

provide context for comparisons between the protected stands

that we inventoried and nearby harvested stands.

Waynesville Case Study

In the Waynesville watershed, we found that most bloodroot

(eight of the nine stands identified) occurs on northern hard-

wood slopes or poplar coves. Within this habitat type, blood-

root stands have a clumped distribution. Eight stands had simi-

lar characteristics. While the mean density of the ninth stand

was not statistically different at the 15% level, it was much

higher than the other stands in absolute terms. This may be due

to unusual stand characteristics also reflected in its small size.

Bloodroot is known to respond to increased sunlight through

increased clonal growth (Marino et al., 1997), and the stand

was located in a patch of sunlight with little overstory cover,

possibly the result of a treefall gap.

Mean petiole diameter of the bloodroot stands is significantly

negatively correlated with average overstory tree dbh within the

range of conditions where bloodroot was found. It is important

to note that excluding the outlier population, all of the stands

are located within areas where average tree dbh is between

27.38 and 36.17 cm. Bloodroot is not found growing naturally

in large open fields or in very young stands with a low mean

tree dbh and lots of competitive herbaceous cover. Preliminary

literature review and canvassing of possible research sites indi-

cated that bloodroot is not found in young stands or dry sites.

Rather, typical sites for bloodroot are medium-sized hardwood

stands on northern aspects. As the mean dbh of mature stands

increases, bloodroot growth may decline. One explanation for

this is that an older mature overstory of large hardwood trees

allows more light to reach the forest floor and increases the

competition from other understory plants. It is also possible that

increased tree growth results in limited nutrients, which may in

turn lead to a decline in bloodroot growth rates.

Allometric Volume Equations

The relationship between easily recognized aboveground

characteristics (petiole height and petiole diameter) and below-

ground biomass of rhizomes was analyzed to assess the feasibil-

ity of restricting harvest to the largest rhizomes. Regression

analyses based on the 174 harvested rhizomes and their corre-

sponding aboveground plant parts reveal that rhizome biomass

can be predicted fairly accurately with two variables: petiole

height (cm) and petiole diameter (cm) (R2 = 0.77; p < 0.0001).

The regression equations demonstrate that harvesters can

estimate belowground biomass based on the observable above

ground plant characteristics of petiole height and petiole diameter.

Regional Bloodroot Sustainability

In a preliminary reconnaissance made when selecting the

Waynesville study site, four additional forests in Western North

Carolina were visited, including a national forest research site

and private and community forests. This confirmed that rich

cove sites provide excellent habitat for bloodroot.

Field observations and a few sample plots were taken in one

of the sites that had been open to bloodroot harvests and subject

to periodic timber harvests. Bloodroot on these lands was

scarce, even on rich cove sites comparable to those sampled in

the Waynesville watershed. The plants had comparable mean

petiole heights to those on the Waynesville watershed, but stand

densities were notably reduced.

Thus, our inventory may provide an upper bound on blood-

root distribution and abundance, since the Waynesville site is

managed under a conservation easement and not subject to

bloodroot harvest. Based on our canvass of potential sites, the

mean density of harvested stands was less than one plant per

square meter compared to 7.2 plants per square meter in the

Waynesville watershed. If the Waynesville high density stand

outlier is removed, the mean stand density drops to 3.7 plants

per square meter, still significantly larger than the harvested

stands. Due to the similarity in forest types and bloodroot plant

sizes, it is likely that this discrepancy in stand density is due to

harvesting pressure. This in turn suggests that some regulation

of harvest (whether by law or by community norms) and/or

active management such as enrichment plantings will be re-

quired to prevent further decline of bloodroot populations.

According to work on the ecological zones of the Southern

Appalachian Mountains by Simon et al. (2005), 12 percent

(695,000 acres) of the Southern Appalachian Mountains are in

Northern Hardwood or Rich Cove ecological zones. If the

Waynesville watershed can be considered representative of

Southern Appalachia, then we can extrapolate from the occur-

rence of bloodroot in 4.2% of the suitable habitat in Waynes-

ville to estimate that there are 56,000 acres of bloodroot in the

Southern Appalachian Mountains. This represents less than one

percent of the total forest area. If the 1,772,000 acres of Mesic

Oak-Hickory (Simon et al., 2005) are added to the total area of

suitable habitat, the total potential bloodroot area would be

about 197,000 or 3.4 percent of total forest area, although this is

likely an over-estimate, because we found only one bloodroot

stand in this forest type.

Furthermore, anecdotal evidence indicates that bloodroot

may be more common in the Waynesville watershed than in the

region as a whole, suggesting that the total area occupied by

bloodroot in Southern Appalachia is even less than projected

above. Sampling more stands under a variety of ownership and

management types would shed further light on whether the

Waynesville stands are representative and whether diminished

stand density is typical of sites that are open to harvest. Last we

offer a few observations about the natural history of bloodroot

and forest management practices. Bloodroot clearly favors deep

rich soils on north and east facing slopes and rich cove sites, as

well as soils that are not too acidic, which leads to domination

by rhododendron. Most of the Waynesville watershed has this

combination of aspect and soils. Furthermore, though not well

documented, our results suggest that bloodroot thrives under a

certain age, species, and density of forest overstory. Most of the

forest in the Waynesville watershed is about 80 - 85 years old

with a general oak-hickory-poplar forest composition, and a

J. FURGURSON ET AL.

218

moderate stand density. The few additional areas where we

observed bloodroot were mature stands with trees 60 to 100

years old, which prevented lush vegetation on the forest floor,

thus allowing the less competitive bloodroot to prosper. Recent

clearcuts and young stands with trees 30 - 50 years old had no

observable bloodroot at all. The dense vegetation of pioneer

species and young saplings resulting in nearly complete forest

floor cover may prevent bloodroot survival. This implies that

older stands of oak-hickory-poplar on good sites are required to

nurture bloodroot, which in turn suggests that landowners face

a trade-off between timber and non-timber production: tracts of

valuable old growth timber should be left unharvested where

conservation of bloodroot is a high priority.

Acknowledgements

We would like to thank the City of Waynesville for allowing

us to conduct our research on their watershed. We would also

like to thank the USDA Forest Service Health Monitoring Pro-

gram. We are grateful to the Revitalization of Traditional

Cherokee Artisan Resources (RTCAR) and the Community

Forestry & Environmental Research Partnerships for funding.

We thank Seth Holling for assistance in the field and Drs.

Jeanine Davis and David Danehower for valuable discussion

and insight.

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