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Invasive grasses, wildfire, and native forest restoration in Hawaii

Publications to Date

Ellsworth LM, Dale AP, Litton CM, Miura T (In Press) Improved fuel moisture prediction in non-native tropical Megathyrsus maximus grasslands using Moderate Resolution Imaging Spectroradiometer (MODIS) derived vegetation indices. International Journal of Wildland Fire.

Powell K, Ellsworth LM, Litton CM, Oleson KLL, Ammondt S (In press) Towards cost-effective restoration: Scaling up restoration in ecosystems degraded by nonnative invasive grass and ungulates. Pacific Science.

Hawbaker TJ, Trauernicht C, Howard SM, Litton CM, Giardina CP, Jacobi JD, Fortini LB, Hughes RF, Selmants PC, Zhu Z (2017) Wi ldland Fires and Greenhouse Gas Emissions in Hawaii. Pages 57-73 in Selmants PC, Giardina CP, Jacobi JD, Zhu Z, (eds). Baseline and projected future carbon storage and carbon fluxes in ecosystems of Hawai‘i. U.S. Geological Survey Professional Paper 1834. (PDF)

Ellsworth LM, Litton CM, Leary JJK (2015) Restoration impacts on fuels and fire potential in a dryland tropical ecosystem dominated by the invasive grass Megathyrsus maximus. Restoration Ecology, 23, 955-963. (PDF)

Friday J, Cordell S, Giardina C, Inman-Narahari F, Koch N, Leary JK, Litton C, Trauernicht C (2015) Future directions for forest restoration in Hawai‘i. New Forests, 46, 733-746. (PDF)

Trauernicht C, Pickett E, Giardina CP, Litton CM, Cordell S, Beavers A (2015) The contemporary scale and context of wildfire in Hawaiʻi. Pacific Science, 69, 427-444. (PDF)

Evans EW, Ellsworth LM, Litton CM (2015) Impact of grazing on fine fuels and potential wildfire behavior in a non-native tropical grassland. Pacific Conservation Biology, 21, 126-132. (PDF)

Pierce AD, Mcdaniel S, Wasser M, Ainsworth A, Litton CM, Giardina CP, Cordell S (2014) Using a prescribed fire to test custom and standard fuel models for fire behavior prediction in a non-native, grass-invaded tropical dry shrubland. Applied Vegetation Science, 17, 700-710. (PDF)

Ellsworth LM, Litton CM, Dale AP, Miura T (2014) Invasive grasses change landscape structure and fire behavior in Hawaii. Applied Vegetation Science, 17, 680-689. (PDF)

Ammondt SA, Litton CM, Ellsworth LM, Leary JK (2013) Restoration of native plant communities in a Hawaiian dry lowland ecosystem dominated by the invasive grass Megathyrsus maximus. Applied Vegetation Science, 16, 29-39. (PDF)

Ellsworth LM, Litton CM, Taylor AD, Kauffman JB (2013) Spatial and temporal variability of guinea grass (Megathyrsus maximus) fuel loads and moisture on Oahu, Hawaii. International Journal of Wildland Fire, 22, 1083-1092. (PDF)

Ammondt SA, Litton CM (2012) Competition between native Hawaiian plants and the invasive grass Megathyrsus maximus: Implications of functional diversity for ecological restoration. Restoration Ecology, 20, 638-646. (PDF)

Litton CM, Kauffman JB (2008) Allometric models for predicting aboveground biomass in two widespread woody plants in Hawaii. Biotropica 40:313-320 (PDF)

Fire is increasingly recognized as an important natural disturbance in the tropics.  However, little is known about the evolutionary history of fire in shaping the structure and function of tropical forests, particularly wet forests. In addition, many tropical forests are now heavily impacted by nonnative species which can disrupt ecosystem processes and services, and alter successional trajectories and disturbance regimes. 

Nonnative grasses such as guinea grass (Megathyrsus maximus), typically degrade remnant native plant communities, and preclude the establishment and restoration of native species assemblages.  Most wildfires in Hawaii are ignited by humans.  In order to continue to utilize natural resources while simultaneously protecting remnant native species and communities, the invasive grass-wildfire cycle needs to be managed and ultimately eliminated. Our research is designed to provide a better understanding of the fuel, climatic, and fire behavior components of the invasive grass-wildfire cycle in Hawaiian terrestrial ecosystems currently dominated by nonnative grasses.  Specifically, this work is designed to improve models to accurately predict the probability of ignition, rate of spread, and fire intensity in nonnative grasslands.  In addition, we are exploring methods to restore native woody plant communities to reduce the likelihood of fire occurrence and spread, to eliminate further conversion of remnant native plant communities to nonnative grasslands, and to increase native biodiversity.  This work is funded by the Department of Defense (U.S. Army Garrison - Oahu), the USDA Forest Service (National Fire Plan), and the the College of Tropical Agriculture and Human Resources - University of Hawaii at Manoa.

Figure 3a. The spread of invasive species, particularly nonnative grasses, and repeated wildfires, both accidental and prescribed, have converted much of Hawaii's dry forest ecosystems to nonnative grasslands.



Figure 3b. Guinea grass (Urochloa maxima), a nonnative invasive grass in Hawaii, forms dense stands that outcompete native plants and has very high fine fuel loads that greatly increase fire potential, spread, and severity.

Figure 3c. A restoration trial with native species assemblages on a guinea grass dominated site, designed to simultaneously restore native biodiversity and decrease the probability and severity of future fire.