HEAR bibliography
Phenology, reproductive potential, seed dispersal and predation, and seedling establishment of three invasive plant species in a Hawaiian rain forest
Medeiros, A.C. (2004)

After rain forest of Haleakala National Park was fenced in the late 1980s, native vegetation responded vigorously yet three problematic plant invaders (Clidemia hirta, Hedychium gardnerianum, and Psidium cattleianum) continued to spread unabated and became of great concern to Park managers. This contribution provides a quantitative assessment of crucial life history junctures (quantitative phenology, reproductive potential, seed dispersal, seed predation, seedling establishment) to assist Haleakala NP and other managers of Hawaiian rain forests. It also provides detailed information for potentially identifying key characteristics in prevention, rapid response, and prioritization of incoming invasive species.

Invasive, non-native plants have clearly emerged as one of the greatest threats to world biodiversity. On Maui island, Kipahulu Valley, managed by Haleakala National Park, contains some of the largest tracts of diverse koa (Acacia koa) and ohia lehua (Metrosideros polymorpha) rain forests in the state. Until recently, the primary threat to this forest was the effects of feral pigs (Sus scrofa). In the mid-1980s, the pigs were removed with a control program and a series of exclosure fences. Following the removal of pigs, native plant species increased and many non-native species decreased. However, the rapid spread rate and apparent ecosystem-modifying properties of three invasive plants began to alarm park resource managers; these include clidemia (Clidemia hirta (L.) D. Don, Melastomataceae), kahili ginger (Hedychium gardnerianum Ker. -Gawl., Zingiberaceae), and strawberry guava (Psidium cattleianum Sabine, Myrtaceae) (hereafter Clidemia, Hedychium, and Psidium). All three species are considered serious threats to wet forest in Hawaii, on other oceanic islands, and elsewhere. I propose to investigate key life history attributes of these three species including phenology, seed dispersal, seed predation, and establishment sites. In the Hawaiian Islands and elsewhere, this study can provide important information for determining priorities and strategies for invasive plant control. On a theoretical level, it contributes to a more complete understanding of the life history attributes of invasive plants, which contributes to our developing model of invasive species ecology. Such a model has the potential to assess life history of non-native species and to predict which have traits that indicate the potential to become serious invaders.