Commercial Harvest of Native Plants . . . Considerations for Biodiversity
by Nancy Sather, Minnesota Department of Natural Resources
In a 1993 market research study conducted for the Minnesota Department of Natural Resource's Division of Forestry, Catherine Mater set the stage for examination of biodiversity issues related to development of markets for Minnesota's non-timber forest products. Meeting the challenge of this statement will be greater than we might think because of the large number of potentially useful species and the variety of harvest patterns that could be used to generate products for the market.
Harvest of non-timber forest products is not a new activity. For example, wild rice and maple sugar have been crucial harvests for the state's Ojibwa people since long before European settlers nearly decimated the state's wild ginseng populations in the late 1800s.
Methods for tapping maple and guidelines for maintaining a healthy sugarbush are well understood. But comparable information on the species' biology and levels of ecologically sustainable harvest is not available for the majority of potentially harvestable native plants.
Mater's market study recognized over 60 potential non-timber forest products in four market categories: dried and preserved florals, herbs and medicinals, decoratives, and smokewoods. These products are derived from over 40 species, including both native and non-native species. The majority of species identified in that project were forest species, but a number of those in the floral/decorative market sector are actually plants of prairies or disturbed areas. The Center for Culture and Ecology Non Traditional Forest Products (NTFP) database, which recognizes a greater variety of product categories including edibles and forage, lists 302 Minnesota species as actually or potentially marketable.
In the absence of hard data, a way to assess what else may be harvested in northern Minnesota is to review Marla Emery's socioeconomic study of wildcrafters in Michigan's Upper Peninsula. This thesis emphasizes the fact that there are a large number of products already being wildcrafted mainly by local people as a form of "invisible livelihood." When Emery first conferred with the U.S. Department of Agriculture Forest Service personnel about the number of NTFPs being used in the Upper Peninsula, Forest Service staff identified seven species in use. Emery's interviews with wildcrafters resulted in a list of 138 products derived from more than 80 species, the majority of which are native in northern Minnesota.
Not included in any of these summaries is the market for live native species for the horticultural market. Many of our native plants are now being raised in Minnesota nurseries, but we know that some are garnered from the wild. Others that may be available in nurseries are not Minnesota strains. For an idea of the number of native plants that are part of the nursery trade, one need only examine the catalog of any of our native plant nurseries.
Putting together the information from these sources, it is clear that upwards of 250 native Minnesota plants are probably already subject to some type of commercial harvest. Twelve of these species are identified on the "At Risk" list as maintained by United Plant Saver's, an herbalist's conservation group dedicated to assuring increasing abundance of medicinal plants currently in decline.
Instead of addressing NTFP product by product, or species by species, let's focus on some general biological issues regarding the harvest of Minnesota native plants, but not restrict ourselves to those growing in forests. The general biological processes and interactions that could be affected by harvest span our forest, wetland, and prairie ecosystems.
Knowledge about species biology and ecology is necessary for each species potentially subject to harvest. Things we need to know about plants to assess the ecological affect of harvests include the following.
Take the question, "Is it native to Minnesota?" Two of the species suggested by Mater as potential NTFP for Minnesota are tansy (Tanecetum vulgare) and baby's breath (Gypsophila spp.). Both are nonnative, invasive species. In fact, tansy is on the noxious weed list in Roseau, Beltrami, Koochiching, Itasca, and Cass counties. These are examples of potentially marketable "wild" species for which we would have few ecological concerns and whose increased commercialization would be favorably regarded by wildcrafters, agricultural inspectors, and conservation biologists alike!
To develop an ecologically sustainable management strategy, we also need to know a number of things about market demands and collection patterns. These include:
Little of the published NTFP or ethnobotanical literature relates specifically to North American, mid-continental, temperate native species. However, we can learn much about trends and general principals from the work done in these other systems. An important differentiation needs to be made at the outset between sustainable harvest and ecological sustainability. As Hall and Bawa note in their review of methods used to assess NTFP harvest in tropical systems, Extraction of NTFP may be economically sustainable if the value, adjusted for inflation, increases or remains constant, but economic sustainability is not always consistent with ecological sustainability.
The parts of plants that are used and harvest practices can affect ecological sustainability at four levels of biological organization: the individual, the population, the community, and the ecosystem.
At the individual level, a plant that is partially harvested may become less vigorous or be more susceptible to disease. The capacity to fruit can also be diminished if the plant's energy is shifted from reproduction to replacement of harvested vegetative material. Direct collection of flowers or fruits may deprive it of its capacity for sexual reproduction. But that capacity may also be intercepted if the flowering parts are never allowed to develop because the vegetative parts on which they grow are harvested before they reach the reproductive state.
Examples would be the timing of harvest of willow and dogwood branches for basket material or lycopodium for ornamental markets. If lycopodium plants take three years to reach reproductive age and are gathered before the fruiting bodies form in the third year, their sexual reproduction would essentially be prevented. Whereas if that harvest occurred after the strobili formed, or early in the fourth year, sexual reproduction would occur. Inability to reproduce sexually also has consequences at the level of population genetics. Intensively harvested populations could thus lose their capability to adapt to changing environmental conditions.
It is also at this level that it is easiest to confound economic and ecological sustainability. Simply counting the number of individuals present in a population is not enough to understand its long-term viability. As Pam Hall and Kamaljit Bawa pointed out in a 1993 study, "Methods to Assess the Impact of Extraction of Non-timber Tropical Forest Products on Plant Populations" (Economic Botany v. 47. Pl 234-247), to monitor harvest impact, demographic studies must track the fate of individuals and assess the structure of the population. Like a human population, a population of plants that are all beyond reproductive age would be doomed. So would a population from which all the plants of reproductive age are being differentially and intensively harvested.
Ginseng (Panax quinquefolius) is probably the best known example of demographic changes resulting from harvest. This species has been harvested in North America since the Colonial period. In 1999 the price for wildcrafted North American ginseng approached $500 a pound. Soaring prices are not only a result of higher demand, but of dwindling supplies. Even with the prevailing U.S. Fish and Wildlife Service standard that U.S. ginseng must be harvested from three-prong plants, the species leads the United Plant Savers' list of species at risk. One way to assess whether ever-younger plants are being harvested is the number of roots per pound.
However, once the "damage has been done" and the population has reached levels of great rarity, this ratio may not change over time. This is the case in Minnesota. In Minnesota, diggers do not need a license, but licensed dealers must report their purchases to the DNR.
Exactly how much ginseng is harvested in Minnesota? Despite undoubtedly dwindling numbers of plants in the wild, Minnesota's harvest has increased from 1,000 to 2,000 pounds in the last decade and a half. At the present time, diggers harvest between 1 and 10 pounds apiece, with an average of 2 pounds per person. They represent a broad demographic cross section, from rural subsistence diggers to professionals who dig for recreation and extra money.
Another Minnesota woodland species that is on the international medicinal market is goldenseal (Hydrastis canadensis). This species is rare enough in Minnesota that it meets the criteria for the state list of endangered and threatened species, even without taking harvest into account. The state endangered species law prohibits "the taking, import, transport, or sale of any endangered species of wild animal, plant, or parts thereof." "Parts" includes leaves, flowers, seeds, and roots.
A number of other Minnesota plants have not been considered rare enough for regulation or protection, but merit our concern because they have demonstrated medicinal value and have been subject to intensive harvest in other parts of the country. Two examples from the United Plant Savers at risk list are bloodroot (Sanguinaria canadensis) and purple coneflower (Echinacea angustifolia). The latter is a dry prairie species whose harvest from the wild in the Great Plains states has reached such alarming levels that moratoriums have been enacted in North Dakota and Montana. Echinacea is a good example of a plant whose market could probably be met by cultivation, but time would be needed to develop the seed supply needed to sustain a stable market resource.
The influence of native plant harvest at the community level is generally not as direct as it is at the level of the individual and the population. For example, commercial harvest of wild fruit, nuts, and grains diminishes the supply available to wildlife. Do we have any real sense of how important this loss could be?
An obvious example is the supply of blueberries available to bears. On the Marcell District of the Chippewa National Forest and nearby George Washington State Forest, Noyce and Coy found the highest blueberry abundance in pine plantations, with the second highest abundance in wet aspen stands. Average per acre production of blueberries across all forest types was approximately 170 pounds per acre. The issue here becomes the volume of harvest in comparison with the supply of berries available in any given year.
Do pickers differentially harvest from pine plantations as compared to wet aspen? Are we willing to forego consistency of supply for the commercial market in years with poor berry production in the interest of supporting wildlife?
Blueberries are one NTFP that has been studied in both the Upper Peninsula and northern Minnesota. Blueberries were the NTFP most commonly identified by interview respondents in Emery's Michigan study. Although respondents gathered a number of products for the commercial market, blueberries were most frequently gathered for personal use.
A similar pattern of response was shown by interviewees in Deborah Shubat's study of Minnesota recreational pickers and methods for improving wild production for recreational use ("Management of Native Lowbush Blueberry for Recreational Picking in Northeastern Minnesota," M.S. Thesis, University of Minnesota, 1983).
The majority of respondents at Shubat's Palisade Head interview site valued the experience of picking as much as the product themselves. All respondents picked for personal use. The three-way allocation of the wild blueberry resource between wildlife, recreational pickers, and commercial pickers may explain why Shubat suggests that if commercial fruit harvest is the objective, cultivation is a better alternative than wildcrafting.
Our ability to understand the affect of NTFP harvest at the community level hinges on our knowledge of the exact relationship between wild animals and the plant species we harvest. Changes in community structure that affect the distribution and abundance of other species may be quite subtle.
An example is the relationship between Magnolia warbler (Dendroica magnolia) and balsam fir. On first glance it might appear that there is plenty of fir in the woods for both greens and warblers. However, the Magnolia warbler is less prone to use the sparse, dead lower branches of fir in closed stands than the abundant, green lower boughs of those younger, more open grown firs that could be just the ones targeted for balsam bough harvest.
Closer examination may reveal that we are actually competing with the bird for a particular growth form, age class, and "accessibility" of the species. Reiterating the suggestions of Hall and Bawa, situations like this require study of harvested and control areas to see whether market bough preferences and harvest methods are compatible with warbler use of the trees.
Another impact of harvest experienced at the community level is the potential for disturbing symbiotic or parasitic relationships between species. One of the species identified in Catherine Mater's 1993 market study was sage, (Artemisia spp.) ("Minnesota Special Forest Products-A Market Study." Minnesota Department of Natural Resources-Division of Forestry, 1993.). This common prairie genus is widespread, and some species can be abundant in disturbed areas. It would be quite possible to develop a marketable supply without harvesting from remaining remnants of dry prairie. However, harvest from native dry prairies might not only impact those communities, it might directly impact a rare broomrape (Orobanche fasciculata ), which is parasitic on sage. Because the species is rare, its locations are documented in the Minnesota Natural Heritage and Nongame Research Program's rare features database. This is an example in which collaboration between conservationists and wildcrafters could help direct harvest into areas that were neither prime examples of native prairie nor habitat for the rare broomrape.
Is agroforestry the answer for ecological sustainability of native plant populations? In comparison to wildcrafting, agroforestry offers the following benefits. It
However, even here there are some ecological concerns. The introduction of non-native stock into natural ecosystems creates a potential for genetic contamination. How great that potential is will depend on the species' life history. For example, even though hybrid hazel may not survive well in closed forest systems, the genus is a heavy producer of wind-borne pollen. Cross-pollination with native hazel in natural ecosystems could result in genetic contamination that might change the adaptability and ecological attributes of this widespread forest shrub.
On the other hand, for self-pollinated or insect-pollinated species that are easily propagated from native sources and can be grown in abundance in a wild-simulated situation, agroforestry may indeed be the answer in allaying loss of wild populations. However, manipulation of habitat for agroforestry can alter both the species composition of the natural community and attributes of an ecosystem. Depending on the timing and method of harvest, both wildcrafting and agroforestry have the potential of causing changes in soil structure. For example, harvest of wetland species using mechanized transport such as ATVs before freeze-up can result in rutting or compaction. Tillage can result in increased soil erosion or oxidation of organic soils. Potential ecosystem changes are actually greater with agroforestry than with wildcrafting, because practices such as fertilization or pesticide use can alter the balance of soil nutrients or result in environmental contamination.
Manipulative methods need not be "artificial" to have a detrimental ecological impact on the natural community. The beneficial influence of periodic fire on native prairie is well documented. However, as demand for native prairie grass seed has risen, some seed producers have moved to annual fire frequencies to enhance seed production. It now appears that such frequencies may shift species composition to native warm season grasses at the expense of native cool season grasses and spring forbs.
Each of the levels of biological organization discussed here has a feedback loop to the supply of harvestable resource, but the directness and magnitude of these feedback loops differs. Direct impacts on the demography or genetics of a population have a strong relationship to future levels of marketable resource. If populations fall below self-sustaining levels or become ill-adapted to changing environmental conditions, resource supply will fall. Indirect impacts at the level of the community are more likely to be regarded as economic externalities, because they are most likely to affect species other than the target NTFP. Only when the inherent ecosystem services of all these species are considered together may it become apparent that there could be an impact on the harvestable resource.
Take, for example, those pesky bears with whom we compete for blueberries. Moving from one area of the forest to another, perhaps at a more suitable successional stage for seedling germination, instead of carting their harvest off to city sewers, bears are much better blueberry dispersal agents than we are!
One of the selling points of wild-harvested products, of course, is their wild look, wild taste, or wild smell. These are attributes best fostered in the ecosystems to which they are naturally adapted, and there is likely a strong feedback loop between changes we may make to the soils, nutrients, and light levels of those ecosystems and the "wildness" of the products we seek to harvest. An extreme example is the difference between the appearance, size, and desirability of ginseng raised under shades and that harvested from the wild.
Just as biological factors contribute to the long-term sustainability of a harvestable resource, there are socioeconomic factors that influence ecological sustainability. These include what the "Man and the Biosphere Mushroom Study in the Pacific Northwest" (AMBIO Special Report 9) mushroom study in the Pacific Northwest refers to as "harvest patterns."
Harvest patterns include the parts of the plant used, how it is harvested, timing and frequency of harvest, proportion of target material harvested per plant, the proportion of the population harvested per season, the geographic concentration or dispersion of the harvest, and the methods used to access the harvest area. The MAB mushroom study differentiates these patterns between local subsistence users, visiting gatherers, and commercial outside gathers.
How we as managers promote harvest, regulate it, establish seasons or harvest limits, open or limit access points, decide to issue permits or licenses, establish fees for those permits and licenses, and coordinate these activities across agencies and administrative boundaries has a profound effect on which patterns of harvest will be used. Ultimately, it is not just the economic sustainability, but the ecological sustainability of the resource that is impacted by such simple decisions as whether to issue single permits for multiple administrative units, thereby dispersing harvest.
Suppose we have a widespread but patchy clonal species whose genetic structure is highly differentiated between populations. If that species is present in four administrative units and one has a less restrictive fee structure or a more liberal harvest limit, one of the genetic strains of that species will bear a larger brunt of collection, losing what may be valuable capabilities to adapt to such situations as climate change or acid rainfall.
The harvest of wild species has a long worldwide history. It is the foundation of all our crops and the majority of our original medicinals. All our cultivated ornamentals have native progenitors. As the MAB mushroom study exhibits, and as we may well discover ourselves if we find a way to assess who is harvesting Minnesota's native plants, there are a variety of constituencies involved in wildcrafting. Their motivations range from personal satisfaction in the process of gathering to commercial profit. Some use harvest to supplement other livelihoods. Others have become "professionals" of a sort, moving with the harvest. Yet others, like members of mycological societies in the Pacific Northwest, harvest for the purpose of study and appreciation.
Hopefully, as we refine our collective strategy for management of Minnesota's native plant harvests, we will be inspired by groups like the MAB study group, who have found a way to assess the biological, social, and economic aspects of NTFP harvest to generate species-specific adaptive management strategies that protect both the ecological and economic resources and meet the needs of all these user groups, including those who just came to look.
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