Daisy tree  (Scalesia pedunculata)

The unique daisy trees of the Galapagos Islands are the plant equivalents of Darwin's finches (3). Although many daisy trees actually grow as shrubs, this species takes the form of a tree; indeed it is one of the largest growing daisy trees (1).

This species of daisy tree is endemic to the Galapagos Islands, where it occurs on the islands of San Cristobal, Santa Cruz, Santiago and Floreana (1).

This sun-loving species forms dense woodlands in highland areas (1) (2).

Little is known of the biology of this species. It reaches maturity after around 15 years. Woodlands of this species typically lack younger trees below the canopy. The entire woodland collapses during very dry or very wet conditions, and shortly after this die-back, seedlings begin to germinate. The natural succession of daisy tree woodlands is a self-cyclic series of build up and subsequent collapse (2).

Threats facing this species include settlement by humans, the spread of invasive introduced species and grazing by livestock, particularly introduced goats (1). Fires and clear-cutting for wood have also been problems (1).

The Botany Department of the Charles Darwin Research Station (CDRS) is carrying out research and surveying the daisy trees of the Galapagos (4). Significant steps forward have been made in methods of eradicating or controlling goats and invasive introduced plant species (4). The CDRS has also proposed that monitoring is required, to keep track of endemic plant populations, allowing changes to be detected. Biological studies of the plants are also needed, so that the threats affecting the species can be identified and better understood (4). In some areas, remnants of Scalesia pedunculata woodland have been fenced to protect them from goat grazing. In these fenced areas, the researchers have found that bird density is higher in the fenced plots of woodland, proving that the fencing programme is beneficial not only for the plants, but also for the animals that depend on them (4).

For more on the conservation of the endemic plants of the Galapagos see:

Botany Department, Charles Darwin Research Foundation (2003) Plant Research for Conservation in Galapagos, Report for the Years 1998-2003 and Challenges for the Future:
http://www.darwinfoundation.org/articles/botany1997-2003.pdf

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