Decision Support to Improve Ridge-to-Reef Stewardship in an Era of Rapid Global Change

In Hawaiʻi the term “ridge to reef” refers to the islands’ relatively short watersheds and the resulting tight linkages between ecological states, human activities, and land management in higher elevations with ecological states at the coasts, as well as the state and functioning of the landscapes that lie between them. Recognizing the need to integrate information from ridge to reef to support sound land management decisions, scientists from Pacific Southwest Research Station and Pacific Northwest Research station have initiated the collaborative development of a bioculturally-based stewardship and decision support framework to characterize and evaluate linkages, trade-offs and synergies among resources that sustain Hawaiian society. The main resource we consider is freshwater that supports native plant and animal communities and benefits people by providing clean, abundant water for municipal uses, agriculture and industry. In addition, we are examining carbon sequestration in natural and working lands supports climate mitigation and soil health, and terrestrial, aquatic, and nearshore diversity supports ecology-focused tourism, subsistence-based economies, and Native Hawaiian lifeways.

This project will:

• Characterize the ridge-to-reef resources of importance to Hawaii Island residents, and assemble geospatial data that captures those resources;
• Assess the threats to those resources (invasive species, fire) under current and projected future climate (warming, drying, sea level rise, increasingly severe, long-lasting and frequent droughts, rising frequency and severity of major storm events;
• Assemble required remotely sensed (UAV, plane, satellite) vegetation time series, statistically and dynamically down-scaled climate data, retrospective climate series; 
• Use the above to model fire and invasive species impacts on watershed function, including downstream water, pollution and sediment delivery into near shore areas; and 
• Integrate collaboratively developed stewardship scenarios for mitigating effects of the threats described above.

This work will integrate and build on research directed at: 

• High resolution climate mapping and knowledge exchange, including drought and warming impacts on wildfire regimes, as well as intensification of tree disease spread across Hawaii Island; 
• Carbon stock and flux mapping and management; 
• Climate impacts on Hawaiian forests; 
• Ridge-to-reef processes and coral health; 
• High resolution wall-to-wall remote sensing across dry, mesic and wet forests; and 
• Decision support modeling. 

Specifically, this research will help integrate two decades of high-resolution vegetation mapping with refined soil and topographic maps and new climate products. These products will be paired with observations of wildfire and hydrologic responses to climatic change at the scale of Hawaiʻi Island to understand how climate change threats affect freshwater, nutrient, and sediment flows to nearshore environments. These synthesized data products will be brought into a numerical modeling environment designed to increase our ability to forecast 1) the interacting effects of climate, wildfire, species invasions and disease on ecosystem composition, structure, function and dynamics and 2) the potential benefits of stewardship practices on ridge-to-reef health.