In addition, most of the Diellia sites have been influenced to a greater or lesser extent by local disturbances caused by trampling by cattle and feral ungulates or by the establishment of alien plants (Wagner 1951; Wood 1999). Diellia species have a short rhizome, very fragile stipes, and slow growth, which evidently make them more vulnerable to the above-mentioned disturbances than many other species (Aguraiuja 2001). At the same time, Diellia ferns seem to prefer sites with sparse vegetation cover and thus may be enhanced by moderate disturbances.