Dominant tree species within a forest have resounding effects on the developmental direction an ecosystem takes. Different types of trees can affect the soil properties, water, light availability, and in our case, understory growth. A large portion of understory plants have medicinal properties, making them of special interest to humans both historically, having been used by Indigenous communities for centuries, and possibly in the future as sources of new medications, especially with the growing trend towards ‘natural’ remedies (Ehrlich 2013). For our project we asked the question: “What understory medicinal plants are present based on dominant tree species in the Morgan Arboretum, and what is the local biodiversity of these plant species?”. Although medicinal plants comprise a wide variety of species, we are focusing on the Canada Mayflower, Solomon’s Seal, Baneberry, and Twisted Stalk.
To test our hypothesis that we would find more biodiversity of medicinal plants in mixed wood deciduous forests we used multiple 100 meter long transects. They extended into the forest at random intervals, perpendicular to a demarcated pedestrian trail on which we observed our tree species. We first identified and recorded the diameter at breast height of the tree species present along our transects. Then we identified the herbaceous species, noting the ones that were recorded to have some medicinal value. Each species had to be within a meter of the transect line on the ground, and their position was recorded. Each transect was located within the Morgan Arboretum, in Beech Maple, sugar maple and coniferous forests. We also observed and recorded necessary information required for the later identification of unknown species. After collecting enough data, we were then able to discern which medicinal species were most prominent among specific types of trees.
Figure 1. The green stars indicate transects 1A and 1B-Beech maple forest. Red stars indicate transects 2A, 2B and 2C-coniferous forest. The black stars are transects 3A, 3B and 3C- Sugar maple forest.
The Canada Mayflower, or Wild lily-of-the-valley (Maianthemum canadense) is a small, perennial plant with two to three smooth heart-shaped leaves. In the spring they have small white flowers. It grows in cool woods, in deciduous, coniferous, and mixed forests, as well as clearings throughout Quebec, except for far North. Some individuals do not produce flowers, and is simply a single leaf rising from rhizomes that form continuous undergrowth. The berries are edible but can be purgatives in excess. The Canada Mayflower was also used by Amerindians as an infusion to relieve headaches and as a gargle for sore throat (Montreal Botanical Garden).
Figure 2. a) Maianthemum canadense. Commonly known as The Canada Mayflower, found in our first transect of the Morgan Arboretum. b) Polygonatum multiflorum. Commonly known as Solomon’s Seal, also found at the first transect of the Morgan Arboretum.
One of the most prevalent of the observed medicinal plants is Polygonatum multiflorum, commonly known as Solomon’s Seal. The plant is not native to Canada and is a perennial that typically grows anywhere and prefers lighter soil and a shady spacial distribution (A Modern Herbal). The roots and the shoots are of medicinal significance. The species is most well known for treating pulmonary consumption and bleeding lungs. However, it can also act as an astringent, demulcent, or tonic to treat menstrual pains, stomach inflammation and dysentery.
White Baneberry, Actaea pachypoda, is a perennial also known as “Doll’s-eyes” due to its distinctive round white berry with a black spot that resembles a pupil, carried by thick, bright red pedicels. It is present only in Southern Quebec and Saguenay, and prefers rich woods, maple groves, and the edges of rivers. Despite its toy-like appearance, the berry is highly poisonous and purgative. The root was once used to make a tea for women who had just given birth for labour pains, as well as for headaches, coughs, menstrual irregularities, colds, and constipation (Montreal Botanical Garden).
Figure 3. a) Actaea pachypoda. Also known as Baneberry, found at our second transect of the Morgan Arboretum. b) Streptopus amplexifolius, commonly known as Twisted Stalk. This sample was found in the Morgan Arboretum at Transect 2C.
Streptopus amplexifolius is a perennial better known to some as Twisted Stalk. It is also called Wild Cucumber because of the taste of the edible green shoots. The plant also produces red to yellow berries, which are edible and have a taste similar to watermelon. In significant quantities, the berries can be used as a laxative or a purgative, but most often the root and foliage are used as a tea. This treats a wide variety of ailments such as an analgesic for internal pains, to induce labor, and to treat kidney problems and gonorrhea (Montana Plant Life).
The dynamic of diversity and abundance of herbaceous plants in the understory are strongly influenced by tree cover. The variables on which tree cover depends are stand composition, time since major disturbances and available sunlight (Bartemucci P., 2006). A dense overstory usually composed of hardwoods and conifers will have a negative effect on understory vegetation as the amount of transmitted light and precipitation, direct or throughfall, reaching the forest floor are limited (Elsevier, 2008). For these reasons, young mixed deciduous forests allow for more light transmission to the ground and soil moisture regardless of disturbances or topography. Nonetheless, an “old” climax forest will have a steady herbaceous composition. Although the climax forest will be less diverse, as the factors affecting the herb layer are more stable (Brewer R., 1980). Furthermore, studies show that the diversity present in coniferous forests is essentially due to two factors. The first is the amount of precipitation reaching the ground rather than solar radiation, since the canopy density doesn’t change throughout the seasons (Wiley , 1969). The second factor is a lower soil pH, which can often impact what grows in the understory (Berger A. & Puettmann K., 2000). There are other variables to consider such as soil properties other than pH, and factors related to the herbaceous species like their growing season or their tolerance to shade (Brewer R., 1980). Deciduous forests host a lot of spring ephemerals that benefit from the increased sunlight in late-spring and early summer before the canopy reforms (Moore M., & Vankat J., 1986). The vertical profile of light transmission exhibits a decent impact on understory diversity but due to the complexity of the subject no clear conclusion have been drawn so far (Bartemucci P., 2006). Within this ecological research there is not a lot known on how the specific local forest types such as Beech, Maple, and Spruce, affect the medicinal biodiversity on the forest floor. Our goal is to fill in these gaps of information so that these relationships can be applied on a local forest system level.
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