Eucalyptus - Eucalyptus As An Invasive Species

Eucalyptus As An Invasive Species

Due to similar favourable climatic conditions, Eucalyptus plantations have often replaced oak woodlands, for example in California, Spain and Portugal. The resulting monocultures have raised concerns about loss of biological diversity, through loss of acorns that mammals and birds feed on, absence of hollows that in oak trees provide shelter and nesting sites for birds and small mammals and for bee colonies, as well as lack of downed trees in managed plantations. A study of the relationship between birds and eucalyptus in the San Francisco Bay Area found that bird diversity was similar in native forest vs. eucalyptus forest but the species were different. One way in which the avifauna changes is that cavity nesting birds including woodpeckers, owls, chickadees, wood ducks, etc. are depauperate in eucalyptus groves because the decay-resistant wood of these trees prevents cavity formation by decay or excavation. Also those bird species that glean insects from foliage, such as warblers and vireos, have population declines when eucalyptus replace oak forest. Birds that do well in eucalyptus groves in California like tall vertical habitat like herons and egrets (possibly because redwood trees are less available), or have longer bills, which may play a role in preventing their nostrils from being clogged by eucalyptus resin/pitch. The Point Reyes Bird Observatory observes that sometimes short-billed birds like the Ruby-crowned Kinglet are found dead beneath eucalyptus trees with their nostrils clogged with pitch.

Monarch butterflies use eucalyptus in California for over-wintering, but in some locations have a preference for Monterey pines.