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Aritcles When some people hear "rare plant," images of beautiful flowers come to mind. Few people, however, conjure up thoughts of mosses, liverworts, lichens, mushrooms and algae. These lower plants - lacking the vascular system of higher plants - are essential to the smooth functioning of natural ecosystems. They are also fascinating to study and many species are quite simply, beautiful. I recently attended a conference of the Native Plant Society of Oregon where I learned about conserving lower plants.
Lower plants serve many important purposes. They are an important part of the food web; providing food to animals, from insects and snails to squirrels and caribou. Freshwater and marine algae are essential to numerous invertebrates, fish, otters, seals and whales. Lower plants provide homes and protection for many invertebrates and fish. Also, they are an essential part of nutrient cycles. Some lichens, for instance, are nitrogen fixers. As miniature chemical factories, they collect nitrogen from the air and change it to a form that other plants can use. When lichens die and decompose, the fixed nitrogen is added to the soil.
Fungal mycorrhizae, which grow connected to the root systems of many plants, greatly increase root surface area and the plants' ability to collect nutrients. Certain orchids are among the higher plants that require unique mycorrhizae to flourish.
Finally, lower plants play a critical role in recycling water. Mosses, for example, act like sponges absorbing large amounts of rainfall that would otherwise soak into the ground or run off into streams and rivers. Later, when the air humidity drops, mosses release the stored water and re-humidify the air.
Loss of habitat is a major threat to mosses, lichens, fungi and algae. In harvesting a forest, we not only remove trees but also strip away many lower plants. Scientists have found that non-vascular plants tend to recover slowly leaving fewer species after a disturbance.
Over-collection is also a serious threat to many lower plants. Lichens and mosses are collected for use in the floral trade. Moss is used extensively as decoration and as a moist packing material for delicate roots of commercial plants. Collectors often collect heavily and take rare species, creating substantial loss to local plant communities. Despite Forest Service regulations, collectors continue to roll entire moss mats off of logs, rocks, and the forest floor and inadvertently remove lichens, insects and amphibians which live among the mosses. The Forest Service has good regulations covering moss and lichen harvest; the regulations, however, are difficult to enforce.
Mushrooms are also collected each year. As long as pickers take only the fruiting body of the mushroom they can be safely collected in large amounts. However, the harvested mushrooms are important to the plant's reproduction and as a rule of thumb should never be entirely removed from any one area. The greatest dangers to mushrooms are soil disturbance and destruction of their host plants.
Pollution is another threat to non-vascular plants. For more than twenty years now we have known that many nitrogen-fixing lichens and mycorrhizae are highly sensitive to pollution. A low diversity of lichens in an area is a strong indicator of high levels of air pollution.
Little protection is currently afforded to lower plants, but awareness is growing. In Oregon, The Nature Conservancy's Heritage Program lists 29 species of mosses, 30 species of liverworts, 28 species of lichens and two species of fungi as rare or threatened. This does not mean that they are legally protected however, and there are no non-vascular plants in Oregon with federal listing.
To learn more about the lower plants, begin in your own backyard. Notice how many different types of lower plants are there, then go further afield. Winter is an especially good time to see lichens and mosses in shrubs and trees, and mosses and liverworts on the ground. When hiking, look for an orange peel fungus - it really does look like a dried peel - a blood spot lichen and a conehead liverwort. The unique and diverse forms of lower plants will amaze you. |
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