USDA Forest Service

Pacific Southwest Research Station

Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Research TopicsTropical Ecosystems

Restoration of Socio-ecological Systems

KREW meteorology station
The endangered dry forest species, locally known as halapepe (Chrysodracon hawaiiensis), surrounded by invasive fire-prone grasses.

Restoration ecology is an innovative science weaving together many disciplines directed at meeting highly applied needs of local communities. In particular, this research discipline offers collaborative partnerships a testing ground for basic questions about sustaining, or in some cases restoring the socio- ecological systems that manage(d) resources across the region.

Because ecosystems and society have changed significantly over the past 200 years, there is a need for and considerable interest in novel approaches to restoration including the use of non-native, but non-invasive species to restore forest ecosystem functioning to degraded lands; community based collaborative approaches for supporting reestablishment of native species in degraded ecosystems, sustaining goods and services for communities, and elevating the role of community members as stewardship knowledge holders, practitioners and decision makers. Similar colonization and deforestation problems have plagued much of the tropics, and solutions developed in the Pacific have potential applicability elsewhere.

IPIF's goal is to provide a scientifically sound basis for the reconstruction and functioning of damaged ecosystems that are self-supporting and, at least to some degree, resilient to subsequent change. Finally, the IPIF relies on a place-based, knowledge-sharing approach as part of our core science mission; to best serve the people of the Pacific, it is critical to recognize that ecosystems of the Pacific are fundamentally coupled to humans through millennia of sustainable use and management for abundance.

Restoration Research Emphasis Areas

Hybrid Ecosystems
Breadfruit (Artocarpus altilis) is an example of a non-native but non-invasive species that can be used in functional forest restoration. Breadfruit or ‘Ulu is a 'canoe plant' one of the species that early Hawaiians brought to the islands.

Researchers at the IPIF have developed and are evaluating the use of "hybrid ecosystems," in which a mix of native and non-native species maintains valuable forest structure and ecosystem services. To quantitatively assess ecological services scientists developed a species functional trait-based optimization approach and tool known as the Restoring Ecosystem Services Tool (REST). For each trait, they have designated a quantitative score based on categories representing the variation within that trait. To evaluate treatment effectiveness, they are tracking biotic and abiotic indicators.

Breaking the Grass/Fire Cycle
Light loving invasive tropical grasses are the primary catalyst fueling wildfires in tropical lowland forests in Hawai’i and elsewhere in the world. Planting forest cover and shade structures can mitigate this risk by reducing available light and effectively shading out these fire adapted grasses.

Researchers at the IPIF are combining newly developed remotely sensed information with field based studies to: Define the current condition and historical changes to tropical dry forest ecosystems in Hawaiʻi; Develop technology for regional restoration planning and ecosystem monitoring; Quantify restoration potential and develop restoration prescriptions for remnant Hawaiian dry forests and shrublands; and Develop effective fuel and fire risk reduction measures that protect dry forest fragments and initiate succession of degraded grasslands into native woody communities.

Tropical Hardwood Tree Improvement and Regeneration Center (HTIRC)
Members of the Tropical HTIRC Advisory Group discussing ʻiliahi (sandalwood, Santalum ellipticum) management at the Hawai‘I Experimental Tropical Forest on Pu‘u Wa‘awa‘a, Hawai’i Island.

Tropical Hardwood Tree Improvement and Regeneration Center (Tropical HTIRC) was founded in 2011 as a collaborative effort between Purdue University, IPIF, and many other collaborators to address the most important challenges facing tropical hardwoods in Hawaiʻi and American-affiliated tropical islands. The objectives of Tropical HTIRC are to: 1) Improve the genetic quality of tropical hardwoods; 2) Develop advanced nursery propagation and seed production technologies; 3) Establish a system of native species research and demonstration trials; 4) Educate future leaders in tree improvement, management, and protection of tropical hardwood forests, and 5) Engage our stakeholders and address their needs by communicating research findings and management recommendations.

Restoration Strategies for Degraded Savannas in the US Affiliated Pacific Islands
Expanding remnant “tree islands” is a successful approach to restoring degraded habitat in Pacific Islands. In this example we show the before photo of a “tree island” that was supplemented with fertilizer and outplantings. In this example we show the after photo of a “tree island” that was supplemented with fertilizer and outplantings. The long-term goal is for these “islands” to eventually reconnect.

Degraded savannas currently account for a large percentage of the land area in these islands. Some of these areas have very steep slopes, are exposed to strong winds, or are being repeatedly burned over time, which can lead to eroded soils and bare areas without vegetation. An interesting feature of these savannas is the presence of patches or islands of trees. These islands present an opportunity for facilitating forest restoration through low input methods (fertilizer, native outplantings, mulch addition, fern pruning) to hasten tree island growth and expansion. A current collaboration between the scientists at the institute, Ngardok Nature Reserve, Palau Forestry, and the Coral Reef Research Foundation created a demonstration and study area of these low input methods utilizing tree islands of different sizes to determine tree growth, island expansion rates, species diversity, and native bird visitations.

Community Based Restoration
Locally-based students erecting an ungulate proof fence which protects a community-based restoration project.

Hawaiʻi has seen a transformation in agency but especially community-based perspectives on how landscapes and seascapes should be managed. In particular, there is significant momentum to reinstitute community-based approaches to resource stewardship, including practices designed to increase the abundance of important cultural and sustenance resources that support communities. This movement has taken several forms including community-based subsistence fishing and forestry areas, and community-based collaborative management. IPIF is actively involved in several of these initiatives (Puʻu Waʻawaʻa CBSFA; Hawaiʻi Conservation Alliance Community SubCommittee; and the HETF), and the coming decade will see a strong aligning of IPIF based research and technical assistance with community-based restoration.