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Modeling the impact of invasive vegetation on stream flow in the Hamakua Coast. Ayron M. Strauch, Univ. of Hawai’i at Manoa Rich MacKenzie , Greg Bruland , Christian Giardina , Chris Heider , Ed Salminen , Tara Holitzki. Using a precipitation gradient to understand climate change.
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Modeling the impact of invasive vegetation on stream flow in the Hamakua Coast Ayron M. Strauch, Univ. of Hawai’i at Manoa Rich MacKenzie, Greg Bruland, Christian Giardina, Chris Heider, Ed Salminen, Tara Holitzki
Plant invasions can also impact hydrology and aquatic ecosystems
Long-term monitoring • Establishes a baseline dataset • Examine inter-annual variations in stream flow • Helps to validate our model
Remote Sensing and Model Development: DHSVM • Data driven- recreate “reality” • Climate, Hydrology, Soils, Vegetation, other data • Compare “reality” with actuality at specific points and actual events on the landscape (gages) • Run Scenarios and Compare Effects
DHSVM: using station data to model hydrology *Current model uses parameters developed for global applications...not very specific to Hawai’ian conditions • 157 Watersheds • Climate • Stream flow • Soil • Vegetation
Reality Check: Validation • Modeled Flow vs Gauge Observation • 97% Agreement in Total Water Balance
Site 90: N. Laupāhoehoe YELLOW: Existing invasive species types RED: 300 m expansion areas
Scenario I: Invasive Species – Laupāhoehoe River % change in monthly flow Average 5-10% less waterCertain years >20% reduction in flows
Moving forward, developing partnerships • integrate research across forest and aquatic ecosystems to examine how climate change and invasive species impact watersheds at the landscape scale • coordinate research amongst various state, federal and NGO’s • provide knowledge and tools to address impacts from climate change and invasive strawberry guava
Future work • continue to improve the DHSVM as well as run the model under different climate scenarios • initiate stream sampling/monitoring over the next four years • set up field experiments to determine how invasive species are impacting sediment loads and hydrology of streams • establish downstream study sites that will include ecological parameters of native gobies (o`opu) and shrimp (opae)
Greg Bruland, Rich MacKenzie, Christian Giardina, Topaz Collins, Ka`eo Duarte, Tom Giamballuca,, Chris Heider, Tara Holitzki, Caitlin Kryss, Imiola Lindsey, Jamie Wong, Tom Schmidt, Keali’i SagumResearch was/is funded by NSF REAP, PRISM, and the USDA FS
Feral pigs may also be influencing hydrology Pig erosion Pig exclusion