Importance of Environmental Factors on Plantings of Wild-Simulated American Ginseng

Progress report for GNE19-221

Project Type: Graduate Student
Funds awarded in 2019: $15,000.00
Projected End Date: 12/31/2021
Grant Recipient: Yale University
Region: Northeast
State: Connecticut
Graduate Student:
Faculty Advisor:
Marlyse Duguid
Yale School of Forestry and Environmental Studies
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Project Information

Project Objectives:
  1. Identify and quantify the importance of direct environmental variables on success (e.g., density and vigor) in wild-simulated American ginseng plantings.
  2. Examine the relationship between common proxy variables (e.g., aspect, indicator species) used in American ginseng siting and direct environmental measures necessary for plant growth and development.
  3. Provide data to farmers and land managers on the most useful and efficient variables for predicting ginseng growth and development in wild-simulated systems.
Introduction:

The purpose of this project is to identify the most important environmental variables driving growth and productivity of American ginseng in wild-simulated forest farming operations.  Forest farming is an agroforestry practice which cultivates medicinal, edible, decorative, and handicraft crops under a forest canopy that is modified or maintained to provide shade levels and habitat which favor growth and enhance production (Chamberlain et al. 2009). American ginseng, Panax quinquefolius, is an understory plant which has been harvested for centuries due to its significant economic value, and is often the focus crop of forest farming operations. Wild ginseng roots can sell for over $1,000 a pound; this high value has caused the plant to become increasingly scarce in the wild (Turner and McGraw 2015). The forest farming of American ginseng has the potential to take pressure off of wild populations of the plant and to provide forest landowners with an additional and sustainable source of land-based income (Burkhart and Jacobson 2008).

Ginseng can be grown using three different cultivation methods: 1) field-cultivated (in tilled beds under artificial shade cloth with heavy fungicide application); 2) forest-grown (using a forest canopy to provide shade but tilling the soil underneath and applying fungicides); and 3) wild-simulated (planting seeds in a forest environment and then allowing them to grow input-free under natural conditions). Of the three methods, wild-simulated production requires the fewest inputs, incurs the lowest costs, is best for native forest, and produces roots of the highest value, with prices equaling that of wild ginseng, potentially over $1,000 a pound (Carroll and Apsley 2013).

The table below quantifies the financial potential of a successful wild-simulated ginseng planting, illustrating the potential gain to forest landowners across the region. 

Wild-Simulated American Ginseng Production Profit Potential on ½ Acre*

Time to first harvest

7-12 years

Seeds planted per ½ acre ($180 per lb.)

10 lbs.

Total labor per ½ acre (hours at $15 per hour)

825

Tools, pest control, fertilizer, and other expenses

$644

Total costs per ½ acre

$14,819

Root yield per ½ acre

80 lbs.

Root price per dry lb.

$850

Gross income per ½ acre

$68,000

Net profit per ½ acre

$53,181

*Adapted from Carroll and Apsley 2013

Like all agricultural operations, however, the probability of the venture depends on the survival of the crop. Unlike most crops, wild-simulated ginseng requires minimal inputs beyond the initial labor of planting. However, ginseng is very particular about where it grows, thriving on cool, moist slopes under a deciduous canopy (Cruse-Sanders 2004). Land managers use environmental indicators such as slope and aspect as well as “indicator species” to determine good planting sites for wild-simulated ginseng (Carroll and Apsley 2013). Yet the survival and vigor of wild-simulated ginseng populations often varies greatly across planting sites, despite the presence of indicator species, and as wild-simulated ginseng typically isn’t harvested for between 7–12 years the germination and long-term survival of wild-simulated populations is critical to the profitability of a forest farming venture.

By comparing plant density and vigor across sites with a number of environmental variables (relative soil moisture, light availability, soil nutrient content, and soil texture) this study aims to explain the major constraints to wild-simulated ginseng survival on otherwise “appropriate” planting sites (i.e. those with the right slope/aspect and where indicator species are present). The aim is that this study will help forest farmers more accurately assess profitable planting sites, thereby increasing farm productivity; reducing wasted time and labor; and increasing the viability of forest farming as an economically and environmentally sustainable land-based venture.

This project represents an important contribution to the scientific literature as well. The threats to established wild-simulated populations in the form of pests such as deer, turkeys, and voles (McGraw 2005); diseases such as Alternaria and Phytophthora (Kim and Park 2013); ginseng theft by “poachers” (Young et al. 2011); and timber harvesting (Chandler and McGraw 2015) have been studied. Strategies for improving the germination of ginseng seed (Li et al. 2000) and increasing its growth through foliar and soil amendments has also been considered (Proctor and Shelp 2014; Olivier et al. 2005).

But the relationship between environmental conditions and the growth and survival of American ginseng in a forested environment—either wild or wild-simulated populations—has not been extensively studied. Research by Robert Beyfuss (2000) examined the importance of soil calcium in determining wild ginseng’s growth; he concluded that wild ginseng’s association with trees that concentrate calcium in their leaves, such as sugar maple, tulip poplar, and black walnut was a product of this calcium’s role in facilitating plant growth. Beyfuss’ study—which has not been corroborated, but is frequently cited by researchers and Technical Service Providers alike—attributed wild ginseng’s relative abundance, growth, and survival to the species it is found in association with.

A 2013 study by Eric Burkhart examined the flora and soil conditions associated with wild and wild-simulated ginseng populations throughout Pennsylvania, in order to develop a scientific basis for using indicator species to identify good sites for wild-simulated ginseng production. Burkhart’s study concluded that in Pennsylvania three species— white ash, Jack-in-the-pulpit, and rattlesnake fern—could be used to identify sites that met this Calcium requirement.

However, a 2015 study by Turner and McGraw called into question the efficacy of using indicator species to identify good wild or wild-simulated ginseng habitat. Their study found that of the 20 putative indicator species they examined, all except one—tulip poplar—were contra-indicators of ginseng. The results of this study indicate that, despite the conventional wisdom that suggests indicator plants can be used to identify good planting sites for wild-simulated American ginseng, much more research is needed to determine their role in site identification.

Additional research (Beyfuss 2000; Beyfuss 2016; Proctor and Shelp 2014; Souther and McGraw 2011; Wagner and McGraw 2013) has examined the role that other environmental factors such as soil moisture, soil nutrients, and available light may be play in the health and survival of wild ginseng populations. However, there is no research of the influence of environmental factors on wild-simulated plantings of ginseng; what little we know about the plant’s growth requirements is limited to wild plants on one end of the spectrum and intensively cultivated plants on the other. Extrapolating relationships from wild plant populations may not be valid.

Thus, research focused explicitly on wild-simulated ginseng operations—those with the greatest potential benefit to farmers and forest landowners—is greatly needed.

Cooperators

Click linked name(s) to expand
  • Anna Plattner (Educator and Researcher)

Research

Materials and methods:

Site Description

The research location was on forestland owned and managed by American Ginseng Pharm (AGP), a wild-simulated American ginseng production forest in the Catskill region of New York, USA. The Catskill Mountains are located in Southeastern New York and constitute the northeastern end of the Appalachian Plateau. The climate is mountainous, with cold winters and moderately cool to warm summers, with an average annual temperature of 5°C. Heavy morning dew and fog are common in the spring, summer, and fall. Annual precipitation is high, around 150 cm (Biscuit Brook figure) (Stoddard and Murdoch 1991, pg. 239-242). The Catskill Mountains are an ancient geological formation, with origins in Devonian period of 419 to 365 million years ago. Sedimentary rocks were deposited in that area, forming the bedrock of the mountains and their fringes. The mountains themselves were formed by a collision between the eastern margin of proto-North American and at least three smaller continents, which resulted in a mountain belt running through New England; this is referred to as the Acadian Orogeny. The weathering of this mountain belt resulted in the “erosion, transport, and deposition of great masses of siliciclastic rock fragments (e.g. sand, mud, silt, and gravel)” which were subsequently buried and lithified (Ver Straeten 2013). The resulting bedrock is therefore sedimentary with  60% sandstone interspersed with conglomerate and 40% mudstone or siltstone (Stoddard and Murdoch 1991, pg. 239). AGP is situated on the northern edge of the Catskill range, in the Oneonta Formation within the Devonian bedrock deposition strata. Reflective of the region generally, the lithology of this formation is characterized by sandstone; minor conglomerates; and red, green, and dark gray shale and mudstone (Ver Straeten 2013).

AGP is a unique experimental agroforestry system with over 324 hectares of native northeast forestland managed for wild-simulated ginseng production. AGP consists of a series of properties across a 113-mile range, spanning the range of the Catskills. The altitude range of planting sites is between 550 and 1,000 meters ASL. The exact location of AGP’s properties will remain undisclosed for security purposes. The large size of AGP land under wild-simulated ginseng production makes it a uniquely valuable site for observational research and data collection.

View of my research sites on the drive up.
The view from the inside of a wild-simulated ginseng farm.
Some seeds planted in 2016 had just germinated three years later.
This simple tool called a densiometer allows you to determine the degree of canopy openness within your forest, potentially a very handy tool for determining appropriate sites for planting ginseng.
American Ginseng Pharm General Manager Anna Plattner helps collect data in the field.
Leaning on my T-bar, used to collect soil samples from my research sites.
A ginseng farmer’s dream – a beautiful four-prong plant.
Working in the lab with Catskill soil.

Experimental Design

Every year since 2012 AGP has planted between 16-24 hectares in wild-simulated ginseng on north and east facing slopes where a range of mesic indicator species are present (Table 1). Stratified American ginseng seed is sourced from commercial ginseng farms in Quebec, and is planted beginning in

[1]. The seeds are broadcast by hand by a team of around 10 people, and is done at a rate between 12–40 kg/ha and recorded. Personnel at the farm are trained to broadcast 4-5 seeds per square foot. To control for seasonal affects we conducted this study on all forested areas planted by AGP in 2016 to examine the first 3 years of germination and growth. The total area planted in 2016 was 17.4 hectares distributed across 22 forest stands

ranging in size from 0.03–0.79 ha. The 22 stands were distributed geographically across two larger sites, named Prattsville and Jump Brook. Using the “Create Random Points” tool in ArcGIS, we distributed 65 points across the entire 17.4 hectares. Each point was given a 7.5-meter buffer around it to avoid observational overlap. Each of the 65 random points served as plot center for a round, 10m radius (28.27 m2) fixed-area plot. For ginseng, understory species composition, and environmental measurements five separate circular quadrats each with a radius of 1m were established, one at plot center and the remaining four quadrats three meters from plot center along cardinal directions (north, south, east, west; Fig. 1).

In order to measure ginseng density and vigor, we recorded every ginseng plant with each of the five smaller quadrats. To assess vigor, we counted the number of leaves and measured the width of the central leaflet on each individual ginseng plant. Prior research indicates that the square of the width of the central leaflet across ginseng species is an economical and accurate way to assess leaf area, which itself correlates with root size (Parmenter and Littlejohn 2000).

In order to assess the degree of shade cover at each plot, we used a convex Forestry Suppliers Spherical Crown Concave Densiometer. The tool uses a convex mirror with a grid laid out on it to display the canopy. The user projects four dots in the corners of each unit of the grid, tallies up the dots and multiplies this number by 1.04. This number is subtracted from 100 to give percent shade cover (Lemmon, 1956). We took four measurements—facing north, east, south, and west—of canopy openness at each of the five quadrats, for a total of twenty canopy measurements at each plot. These were averaged to provide one measurement of canopy openness per plot.

For soil measurements, we collected composite soil samples of 15 two-centimeter cores, which represented 3 samples from each quadrat. Each core began below the leaf litter at the Oa horizon and was 12 cm deep. We quantified soil texture with dispersion of soil particles using sodium hexametaphosphate followed by the 1) isolation of the sand fraction using a 0.053 mm sieve, and 2) separation of the silt and clay fractions by settling. Soil pH analysis was done using a modified Mehlich and Morgan Extraction, and percent soil organic matter (SOM) by mass loss on ignition (LOI) at 500°C for 12 hours. The University of Connecticut’s soil analysis lab conducted these analyses.

We quantified soil moisture in multiple ways. First, relative soil moisture was measured in situ as volumetric water content (VWC) using a handheld Hydrosense II Soil Water Content Measurement System (Campbell Scientific, Inc., Logan, UT, USA), with 12cm rods. Three measurements were taken at each of the five quadrats during an extended dry period of at least 72 hours. We conducted all VWC measurements within a two-day window to establish relative soil moisture across plots. Soil samples were used to calculate the water holding capacity of homogenized soils. Subsamples of fresh soil were used to measure field moisture content (105°C for 24 h) and water holding capacity (samples fully saturated, then drained for two hours, and dried at 105°C for 24 hours) (Keiser 2016).

At each 10-meter radius plot, we identified to species and measured every tree at diameter at breast height (dbh, greater than 5 centimeters at 1.3 meters above the ground). We classified each individual as either an arbuscular mycorrhizal fungi (AMF) or ectomycorrhizal fungi (EF) associate using Citation. Within each quadrat we performed presence-absence analysis on the understory plant community using a list of indicator species provided by AGP, itself an aggregation taken from other scientific works and field experience in the Catskill region. From these numbers overall basal area was calculated, as an easily measured proxy variable reflecting a variety of stand traits, tree density and composition, and the ratio of AMF:EF species as a proxy for available microbial partnerships.

Data Analyses

As each of the 22 forest stands planted in 2016 were seeded at a different rate, the number of ginseng plants present in each stand was normalized against seeding rate to allow for cross-stand comparison, by multiplying the seeding rate by the total area of each plot—itself an aggregate of five subplots—and dividing the number of plants present by the new pounds per plot measurement number, normalized across all plots. Plants per pounds of seeds planted, leaf width, and average number of leaves across all plants are the response variables we used for analysis, while the environmental measures recorded—soil nutrients, pH, texture, and moisture; canopy openness; tree associations and microbial partnerships were the independent variables measured.

We examined linear relationships between variables, but additional analysis will be required to disentangle confounding variables. We will perform ANOVA, cluster, and PCA analyses to shed light on the most important factors acting on the response variables (data analysis in progress).

[1] Standard practice is to plant stratified ginseng seeds during the fall—once the tree leaves have begun to fall but before the ground is freezing—but because of the vast areas and large quantity of seed AGP must plant they start earlier in the season.

Participation Summary
1 Farmer participating in research

Education & Outreach Activities and Participation Summary

2 Published press articles, newsletters
1 Webinars / talks / presentations
1 Gave a lecture on my SARE-funded research in a graduate-level seminar course "The Science and Practice of Temperate Agroforestry" offered at the Yale School of the Environment, to a group of 22 students studying forestry and sustainable land management.

Participation Summary

35 Farmers
7 Number of agricultural educator or service providers reached through education and outreach activities
Education/outreach description:

(Picture taken during a presentation at the Perennial Farm Gathering virtual conference, held Dec. 6-9, 2020)

Despite the difficulties brought on by COVID-19, I was able to make substantial progress in 2020. I am in the process of preparing a manuscript for submission to the journal Agroforestry Systems based on my research made possible through this grant (to be formally submitted in 2021). I presented the results of my project at the Perennial Farm Gathering conference, co-sponsored by the Association for Temperate Agroforestry (AFTA) and the Savanna Institute, to a group of 42 farmer and agricultural service providers. Through a partnership with the farm managers at American Ginseng Pharm, they wrote up articles highlighting this research in AFTA’s newsletter, The Temperate Agroforester, and in the newsletter of United Plant Savers. I will also be presenting this research at the New England Society of American Foresters (NESAF) conference on March 22nd of 2021, at AFTA’s biennial conference in July of this year, and during the Summer Research Seminar series held through the Quiet Corner Initiative (QCI) at the Yale-Myers Forest in Eastford, CT at an event drawing from QCI’s membership made up of farmers and private forest landowners. Factsheets distributed at that event with further share out our results.  

Project Outcomes

1 Grant applied for that built upon this project
1 New working collaboration
Project outcomes:

This project provided us with practical insight into ways that farmers can more efficiently and effectively approach the intentional cultivation of ginseng in their woodlots using a wild-simulated technique. The results of our research indicate that the integration of silvicultural techniques, namely the light thinning of trees in the forested area where ginseng is being planted, in order to increase the levels of sunlight reaching the forest floor, would have a significantly positive effect on ginseng survival, growth, and development. It also creates additional opportunities for low-impact income generation through the selective harvesting of trees from the forest. This could range from merchantable saw-logs to small-diameter trees that could be used for mushroom cultivation or as firewood. This type of low-impact management has few barriers to entry, and constitutes an easy intervention for forest farmers that our research indicates will have a positive impact on the success of their wild-simulated plantings.     

Knowledge Gained:

We are in the process of finalizing the results of our research, but this project has already provided critical insight into the environmental factors most responsible for the growth and development of wild-simulated ginseng. Like all good research, this project has raised as many questions as it answered, which has generated new research questions to be taken up by myself and/or other students at Yale’s School of the Environment through the relationship between myself, my advisor, and other faculty at the school. This project has also raised the profile of agroforestry at Yale’s Forest School, where the topic has been growing as an area of research and practice on the school’s forest properties. My own career trajectory has been directly shaped by this project, as I have stepped into a post-graduate fellowship position with the school and submitted another SARE proposal (this time a full institutional SARE proposal) to expand this research to a greater number of commercially significant understory species across new research sites ranging throughout the Northeast.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.