Joanne M. Sharpe

Fern Ecology: Ferns, disturbance and succession

Key points 1. Ferns often colonize habitats disturbed by tectonic activity, wind, water, fire and humans. 2. Fern dispersal into disturbed habitats can result from long distance movement of spores but is usually by short distance spore dispersal or vegetative expansion of nearby plants. 3. Rapid establishment and dense growth can make ferns competitive with other vascular plants through light reduction and nutrient uptake or immobilization. Fern thickets can delay successional transitions but ferns also provide regeneration sites for other species and stabilize slopes. Fern influences may vary across environmental resource (e.g., light, water, nutrients) and topographic gradients. 4. Ferns can have important roles in the restoration of disturbed ecosystems. Introduction A typical image of fern habitat is a wet, shady forest untouched by disturbance. In fact, many ferns colonize recently disturbed and exposed areas such as scoured riverbanks (Reudink et al .,2005) or the uprooted pits, mounds and trunks of fallen trees (Peterson et al ., 1990; Nadkarni and Wheelwright, 2000). Ferns tolerate a wide range of environmental conditions (Hemp, 2001), and some species can colonize such highly disturbed habitats as lava flows, dunes, landslides or floodplains as well as areas of forests that have been damaged by burning, ice storms, hurricanes or logging (Walker et al ., 1996b; Barson, 1997; Russell et al ., 1998; Arens and Sanchez Baracaldo, 1998, 2000; Woods, 2002). One reason some ferns readily colonize recent disturbances is that they have widely dispersed spores that reach even the most remote islands (see Chapter 2; Carlquist, 1980).