|What Plants Can Live in Caves?|
At the entrance and the twilight zone of caves, there is a little light for plants to live in. The next time you are a cave entrance, look around you for plants. Trees or grasses may be growing at the entrance and even out of the rocks on the sides of the entrance. Mosses, ferns, and/or liverworts may be growing on the ground at the cave entrance or in the twilight zone. Mosses, ferns and liverworts grow in the cool, moist environment provided by the cave entrance. Since caves are usually a constant temperature and high humidity inside, the plants at the entrance can enjoy a more stable temperature and moist environment than plants out in the open. As you walk into the twilight zone, cyanobacteria, a bacteria that has chlorophyll, cause all the rocks facing the entrance to be a shade of green.
Remember, all plants grow up, and down. Root systems of plants grow into many caves. Some roots are then covered by growing formations, causing rootites to form in the cave. Other roots find cave streams and grow dense root mats that are very important to the animals living there. Stream caves with root mats have a much higher number of cave creatures living in them than caves with no mats.
Although plants do not directly grow into the cave, the plants on the surface around the cave are very important to the cave ecology. The litter from the plants on the surface donates the CO2 that creates carbonic acid that helps eat away the limestone slowly to form caves. Also growing roots release acids and other compounds that help them break through the rock to grow, which can help the break open and create new cave. In most caves in the east, the inflow of organic (mainly plant) debris is the main food source, along with guano, for the cave creatures. Many cave creatures will actually time their copulation to the spring rains that bring in the plant debris, so that their young will be born at a time when the amount bacteria eating the debris will be the highest. Finally, plant systems on the surface affect the nutrient cycling and water quality and quantity coming into the cave, making water more or less available depending on the plants.
Clearly, plants are very important to caves, although they do not directly grow in most caves. If you can find a root in a cave, go look at it closely. Usually water will collect on the root, making it sparkle. Cave animals may be hiding in it or nearby. Formations may be starting to grow in it. As you can see, that root is deficiently part of the cave.
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Extensive roots systems (with fungus?) can be found in Carmichael Cave, Mt. Eccles, Victoria, Australia.