Moss, lichen, liverwort; we see these tiny plants every day, but do we ever stop to really think about them? For our natural history research project, we decided to learn more about these plants, also referred to as bryophytes. It was this curiosity that lead to our research question, which is: In what forest types will bryophytes grow the most abundantly in the Morgan Arboretum?
What are Bryophytes?
It is important to first understand what a bryophyte is, and how to identify them. Bryophytes are a major classification of land plants that do not possess a true vascular system or root system. They range in size and are typically green due to chlorophyll, the green pigment found in chloroplasts. This makes them photoautotrophic, so they make their own energy from water, carbon dioxide and sunlight through photosynthesis (Lepp, 2008).
Bryophytes include three phylum (a classification of organisms): Moss (Phylum Bryophyta), Liverworts (Phylum Marchantiophyta) and Hornworts (Phylum Anthocerotophyta) (Crandall-Stotler, 2005). These three phyla have the same life cycle; the only difference is observed in the organization of their leaves. Moss have tiny stems on which leaves are arranged in spirals, whereas liverworts have leafy shoots or flattened thalli (vegetative parts) where the leaves are arranged around two lateral ranks (Crandall-Stotler, 2005). Hornworts look like liverworts, but have a different metabolism. Liverworts synthesize oils and store them as oil bodies which make them have a spicy aroma, whereas hornworts require ammonium for their metabolism and secrete carbohydrate for cyanobacteria (Crandall-Stotler, 2005).
The reproduction of bryophytes has been researched heavily to better understand the role bryophytes play in the environment. A study in 1979 was conducted, by Heinjo During, to examine the history traits and life strategies of bryophytes. It was found that bryophytes can reproduce asexually and sexually, depending on the species. Asexual reproduction can occur many ways, one being simple fragmentation. This occurs if a piece of the bryophyte breaks off and is transported to a new suitable environment, where it can grow into a new plant. Sexual reproduction happens through the dispersal of spores, which are formed when the male gamete (sperm) is carried to the female gamete (egg) by water, and fertilization occurs. Once this happens, the newly formed spore can be carried (usually by wind) to new surfaces and begin to grow (Lepp, 2008).
The history traits of bryophytes also reveal that many species may have co-evolved with other organisms to better adapt to their environment. An example of this is the mutualistic interaction some bryophytes have with fungi shown in the 2014 paper “Forestry impacts on the hidden fungal biodiversity associated with bryophytes”, where the amount of fungal biodiversity varied with the species and relative amount of bryophytes present.
Bryophytes are also key pioneer species meaning they are some of the first organisms to colonize previously disrupted or damaged ecosystems. This was demonstrated in a 1982 experiment by Diana Duncan following the growth of bryophytes after a forest fire, which found bryophyte spores were particularly well suited for germination on burnt soils.
It is commonly thought that bryophytes can only be found in moist environments, but that is not always the case. They are found in nearly every habitat including the arctic and the desert, with the only exception being in the ocean. They can also grow on all kinds of surfaces like rocks, tree trunks, bones, and even discarded shoes (Lepp, 2008). Bryophytes also grow more abundantly in areas with little pollution, so they can be an indicator of a healthier environment (Lepp, 2008).
Bryophytes also play an important ecological role. “They provide seed beds for the larger plants of the community, they capture and recycle nutrients that are washed with rainwater and they bind the soil to keep it from eroding” (Crandall-Stotler, 2005).
The abundance of bryophytes is dependent on many factors. Research in 2006 by Andersson and Hytteborn measured bryophyte occurrence and the relative amount of decaying wood in natural verses managed forests. They showed that natural forests had more decaying wood in more stages than managed forests which allowed for greater bryophyte richness in natural forests. This is important for our experiment because the Morgan Arboretum is partially managed and is a factor that might affect our data.
We were able to spend three lab sessions looking at bryophytes in the Morgan Arboretum, a 245-hectare reserve in the western tip of Montreal, and mere minutes from our classroom on the McGill University’s Macdonald Campus.
In order to answer our research question, we looked at the amount of moss, lichen, and other bryophytes in three distinct forest types dominated by a specific species of tree: Beech, Sugar Maple, and Hemlock. This gave us a diverse range of habitats while still being manageable for four undergrads with heavy backpacks in cold October.
To record and measure each forest uniformly, we measured out ten plots, each five by five meters. Each plot was chosen somewhat arbitrarily; we mapped out each forest type along a trail and made our plots about 30 meters apart along the trail and 10 meters into the woods from the trail.
Our experimental method!
Our materials consisted of a tape measure, a clipboard, and a camera; we used our bags to mark the corners of each plot. Once we had an area plotted out, we looked at the trunks and roots of trees, rocks, soil, and dead or decaying matter for any moss, lichen or liverworts. We created a scale to measure of the amount of bryophytes, ranking the percentage of biomass coverage from 0-5, 0 being nothing and 5 being 80-100% coverage. This allowed us to compare each forest type, and each habitat of moss within each forest. We also noted any overall trends in each area, such as the lack of lichen on Beech trunks and the numerous moss covered rocks in Maple-dominated forests.
Andersson, L. I. and Hytteborn, H. (1991), Bryophytes and decaying wood– a comparison between managed and natural forest. Ecography, 14: 121–130. doi: 10.1111/j.1600-0587.1991.tb00642.x
Birse, EM; Landsberg, SY & Gimingham, CH. (1957). The Effects of Burial by Sand on Dune Mosses. Transactions of the British Bryological Society, 3, 285-301.
Crandall-Stotler, B (2005). What are bryophytes? Department of Plant Biology, Southern Illinois University, Carbondale, IL 62901-6509. Retrieved from http://bryophytes.plant.siu.edu/ bryojustified.html
Davey, M., Kauserud, H., & Ohlson, M. (2014). Forestry impacts on the hidden fungal biodiversity associated with bryophytes. FEMS Microbiol Ecol FEMS Microbiology Ecology, 90(1), 313-325. doi:10.1111/1574-6941.12386
Duncan, D., & Dalton, P. (1982). Recolonisation by bryophytes following fire. Journal of Bryology, 12(1), 53-63. doi:10.1179/jbr.1922.214.171.124
During, H. J.. (1979). Life Strategies of Bryophytes: A Preliminary Review. Lindbergia, 5(1), 2–18. Retrieved from http://www.jstor.org/stable/20149317
Lepp, H. (2008, April 15). What is a Bryophyte? Retrieved October 26, 2015.