Terrestrial Ecosystems
Partula radiolata (tree snail) of Guam is a listed Critically Endangered species (IUCN). Photo © USFWS Pacific Region, 2012.
The Pacific Islands are host to diverse and fragile terrestrial (meaning “land-based”) ecosystems that provide people of the region with food, income, recreation, shared cultural heritage, and many other benefits. Terrestrial ecosystems take diverse forms and are distinct between high islands and low islands. The wide range of ecosystem types on Pacific Islands include, for example, the high-elevation native cloud forests and bogs found on some high islands and the coastal strand ecosystems of many low islands and coastal areas of high islands.
These ecosystems and their services are at risk from climate change and local stress from human activities. The physical and chemical changes in the environment resulting from climate change have cascading impacts on species composition and diversity, soil conditions, and habitat availability. Often these impacts combine to limit ecosystem function and reduce biodiversity.
Key Message
Increasing temperatures, and in some areas reduced rainfall, will stress native Pacific Island plant and animal populations and species, especially in high-elevation ecosystems, with increased exposure to non-native biological invasions and fire, and with extinctions a likely result.
Observed trends, future projections, and impacts
- Surface air temperature has risen over the Pacific Islands region over the last century. This warming is spatially and temporally variable, with more warming at higher elevations and at night. Minimum and maximum temperatures and the frequency and intensity of days of extreme heat are projected to increase across the region. Warming at high elevations could exacerbate invasive species problems and alter the distribution of native species in high island ecosystems.
- Birds that inhabit high elevation forests on high islands, such as the Hawaiian Islands, will be increasingly threatened by diminishing habitat and an increase in the altitudinal range of vectors that carry avian malaria (Atkinson et al. 2013 & 2014; Benning et al. 2002).
- Changes in precipitation patterns may lead to changes in terrestrial species distribution.
- Highly-specialized and endemic species are particularly vulnerable to precipitation changes. Populations of the Haleakala Silversword, endemic to the alpine environment of Mount Haleakala, Maui, Hawai‘i, have declined, correlated with decreased rainfall and an increase in the frequency of the trade wind inversion (TWI) (Krushelnycky et al. 2013 & 2016). See Freshwater and Drought for more information on trends and projections for precipitation and TWI.
- Sea level in the region has risen at a rate greater than the global average. Sea-level rise is of critical concern to low-lying atolls where overwash and inundation will contribute to loss of terrestrial ecosystems.
- Projected increase in tropical cyclone intensity could result in habitat destruction of terrestrial ecosystems (forests), potentially accelerating the spread of invasive species.
The preceding text is excerpted and abridged from this chapter, which should be cited as:
Parker, B., & Miller, S. E. (2012). Marine, Freshwater, and Terrestrial Ecosystems on Pacific Islands. In V. W. Keener, J. J. Marra, M. L. Finucane, D. Spooner, & M. H. Smith (Eds.), Climate Change and Pacific Islands: Indicators and Impacts. Report for the 2012 Pacific Islands Regional Climate Assessment (PIRCA). Washington, DC: Island Press.
Content: Terrestrial Ecosystems
PIRCA 