Coral Reef Research Foundation | Terrestrial Environments
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Terrestrial Environments

What happens on land is important for reefs and marine environments, with nutrients and sediments coming off the land affecting nearshore environments.

CRRF collaborates with the USDA Forest Service Institute of Pacific Islands Forestry in Hilo and several other local partners, Ngardok Nature Reserve, Palau Forestry and the Belau National Museum, looking at several aspects of the terrestrial environments of Babeldaob Island, the largest island (400 sq km) in Palau and the second largest island in Micronesia. The field program has been run by Julian Dendy since 2011.

The program has three complimentary components:

Landscape Change
Forest Dynamics
Fire Mapping

Landscape Change – Why study landscape change?

Knowing how landscape has changed over time provides valuable information for conservation land managers and for guiding community development and restoration efforts.

Babeldaob Island contains the largest area of intact native lowland forest in the Pacific. The forests of Babeldaob are the most diverse forests in Micronesia and are vital to maintain Babeldaob’s watersheds, near shore environment, and forest resources. To understand where and how much forests and vegetation have changed over time on Babeldaob, a collaborative group from the Palau Coral Reef Research Foundation, the USDA Forest Service, and Palau Forestry analyzed historical aerial photos and satellite imagery over a 60 year time period of 4 land cover categories: forest, mangrove, non-forest vegetation (savanna), and non-vegetation (i.e., roads, buildings). This method allows us to understand how the landscape of Babeldaob has changed over time.

Manual classification was used to classify aerial photos from 1947, 1976, and 1992 and automated classification was used to classify satellite imagery from 2001 and 2005. Maps of Babeldaob Island land cover over time and detailed images from Melekeok state showing specific areas of forest cover increase and areas where forest had been cleared between mapped periods. Babeldaob has a moderately fragmented landscape with relatively stable forest interiors and dynamic forest and savanna edges. Forest cover has been increasing, despite some forest edge clearance and increases of non-vegetation from road construction and other urban development.

Forest Dynamics – Seeing the Forests for the Trees

In addition to monitoring landscape change via the large scale image analyses, the USDA Forest Service and collaborators have also implemented an upland forest monitoring protocol within a permanent plot in Palau. This detailed study of a single diverse area will help meet the terrestrial monitoring objectives of the Micronesian Challenge and provides detailed information on the growth, survivorship and mortality of individual plants. An autonomous weather station on site provides detailed data on the conditions affecting the plot. The Ngardok Nature Reserve was selected as the site for the first permanent forest dynamic plot in Palau and uses the methodology of the Smithsonian’s Center for Tropical Forest Science (CTFS) Permanent Plot Network. This very high resolution measurement program gives baseline information on forest changes and allows for detection of sensitivities of recruitment, growth and death to stressors like climate warming and drought.

Knowing about Palau’s forests is important for many reasons, including the ecosystem services (supply of freshwater, control of flooding and erosion, forest products, wildlife habitats, recreational activities) provided. This knowledge allows the comparison of ecological properties of Palauan forests with those of forest plots in tropical and temperate forests around the world. The Palau plot (NNR) contains a similar density of tree stems per hectare as other tropical forests in the CTFS network, but contains three times the number of tree species as Hawaii’s permanent plots, highlighting Palau’s high biodiversity for a pacific island.

Mapping Fire – A Major Disturbance to Terrestrial Habitats

Wild fires on Babeldaob are entirely human derived and are a significant threat to forests, limiting natural forest regeneration processes. The number of wild fires, the extent of area burned, and the threat they pose to forests were not well understood previously.  This program began to document fire occurrence for the island and the reasons for each fire ignition. Fire perimeters have been documented on the island since 2012 utilizing current aerial photos and handheld global positioning system (GPS) data to maintain a geo-referenced database (GIS). Maps have been produced for land managers to document state level fire information, inter-annual fire variability, fire within conservation areas, and to inform communities with wild fire hotspots where education and outreach has been targeted to help reduce fire occurrence. This work has highlighted that preventing wild fires is critical to conserving Babeldaob’s watersheds, near shore environments and forest resources.

New online satellite imagery resources have allowed for improved efficiency and coverage of wildfire mapping, and since 2015/2016 the wildfire mapping effort has expanded to include the islands of Guam and Yap, in addition to Babeldaob.  So far this effort has shown that wildfires on Pacific Islands can burn more area proportionally than in the continental Western US, and that during dry periods the extent of burned area can increase dramatically.