Ecology of ferns
Although often common, ferns rarely dominate the vegetation. They mainly frequent damp places since most are limited in their distribution by the need for damp ground for spore germination and gametophyte growth. The enormous numbers and wide distribution of spores makes them good colonizers of suitable sites and many are pioneers, quick to exploit gaps. They are frequently found in shady situations under dense tree canopy or in rocky crevices. In the tropics, many ferns are epiphytic and they can be among the commonest epiphytes in drier parts of the rainforest; epiphytic ferns include the birdsnest fern which can grow to 3 m across. Several species, such as bracken, Pteridium aquilinum, spread vegetatively with branching rhizomes. These can spread tocover large areas, usually where the soil has eroded or degraded as a result ofcultivation or forest clearance, and often well away from damp ground. Brackenis one of the world’s most common plants, sometimes covering areas of moorland,and in places is considered a serious plant pest.
Very few animals eat ferns although there are a number of specialist insect feeders. Grazing animals may eat developing shoots. Some ferns contain high concentrations of insect molting hormone which may make them toxic.