Pacific Southwest Research Station

Education

Ph.D. 1997. Department of Forest Science, Oregon State University, Corvallis, Oregon.
M.S. 1992. Department of Biological Sciences, Stanford University, Stanford, California.
B.A. 1991. Department of Human Biology, Stanford University, Stanford, California.

Research Interests/Duties

Ecosystem-scale impacts of invasive species and land cover/land use change, fire ecology, carbon and nutrient storage and cycling, primary and secondary forest succession.

Current Emphases, Studies, Projects

Impacts of the fast-growing, N-fixing tree, Falcataria moluccana, on the function and structure of early successional lowland wet forests of Hawaii. Results indicate that Falcataria increases inputs of N and P via litterfall, increases rates of decomposition, and increases soil N and P availability relative to uninvaded, native-dominated stands. Such functional changes coincides with substantial alteration of forest structure as well; Falcataria hastens the loss of dominant native species and facilitates the invasion of other non-native species. Such N-fixing trees have the potential to alter nutrient status and cycling of streams and coastal zones in Hawaii and elsewhere in the Pacific. In collaboration with UH and Hawaii Department of Health scientists, we are conducting NOAA-funded research to determine how Falcataria alters stream chemistry and biology in watersheds of East Hawai'i.

Effects Falcataria on densities of the invasive coqui frog. Invasive species also may have impacts across trophic levels. With UHH colleagues we are conducting NSF-funded research on the effects of increased resource availability from Falcataria trees on densities and rates of spread of the coqui frog.

Use of remote sensing to investigate impacts of invasive species on ecosystem processes. We are collaborating with scientists from the Carnegie Institute of Washington and Stanford University to use state-of-the-art remote-sensing tools to quantify ecosystem characteristics (e.g., canopy N and P, forest structure, total aboveground water) and to evaluate the impacts of invasive species at scales from forests to landscapes and regions,

Composition and structure of native lowland wet forests. With UH-PIPES interns we are studying the few remaining stands of native-dominated lowland wet forests in Hawaii to determine how they vary with regard to substrate age and type and how susceptible they are to invasion. Other studies include impacts of woody plant encroachment on C and N storage and cycling in temperate savannas of North Texas, and quantification of aboveground and soil C pools in Costa Rican forests along gradients of temperature, precipitation, and land use.

Selected Publications

Hughes RF, Uowolo AL, Togia TP. 2012. Effective control of Falcataria moluccana in forests of American Samoa: Managing invasive species in concert with ecological processes. Biological Invasions. Doi: 10.1007/s10530-011-0164-y.

Mascaro J, Litton CM, Hughes RF, Uowolo AL, Schnitzer SA. 2011. Minimizing bias in biomass allometry: Model selection and log transformation of data. Biotropica. doi: 10.1111/j.1744-7429.2011.00798.x.

Mascaro JT, Hughes RF, Schnitzer SA. 2011. Novel forests maintain ecosystem processes after decline of native tree species. Ecological Monographs, in press.

D’Antonio CM, Hughes RF, Tunison JT. 2011. Long term impacts of invasive grasses and subsequent fire in seasonally dry Hawaiian woodlands. Ecological Applications 21:1617-1628.

Asner GP, Hughes RF, Mascaro J, Uowolo AL, Knapp DE, Jacobson J, Kennedy-Bowdoin T, Clark JK. 2011. High-resolution carbon mapping on the million-hectare Island of Hawai‘i. Frontiers in Ecology and the Environment doi:10.1890/100179.

Asner GP, Powell GVN, Mascaro J, Knapp DE, Clark JK, Jacobson J, Kennedy-Bowdoin T, Balaji A, Paez-Acosta G, Victoria E, Secada L, Valqui M, Hughes RF. 2010. High-resolution forest carbon stocks and emissions in the Amazon. Proceedings of the National Academy of Sciences 107:16738-16742.

Kauffman JB, Hughes RF, Heider C. 2009. Dynamics of C and nutrient pools associated with land conversion and abandonment in neotropical landscapes. Ecological Applications 19:1211-1222.

Asner GP, Hughes RF, Varga TA, Knapp DE, Kennedy-Bowdoin T. 2009. Environmental controls over aboveground biomass throughout a tropical rain forest. Ecosystems 12:261-278.

Asner GP, Hughes RF, Vitousek PM, Knapp DE, Kennedy-Bowdoin T, Boardman J, Martin RE, Eastwood M, Green RO. 2008. Invasive plants transform the three-dimensional structure of rain forests. Proceedings of the National Academy of Science 105:4519-4523.

Asner GP, Jones MO, Martin RE, Knapp DE, Hughes RF. 2008. Remote sensing of native and invasive species in Hawaiian forests. Remote Sensing of the Environment 112:1912-1926.

Asner GP, Knapp DE, Kennedy-Bowdoin T, Jones MO, Martin RE, Boardman J, Hughes RF. 2008. Invasive species detection in Hawaiian Rainforests using in flight fusion of airborne imaging spectroscopy and LiDAR. Remote Sensing of the Environment 112:1942-1955.

Mascaro J, Becklund KK, Hughes RF, Schnitzer SA. 2008. Limited native plant regeneration in novel, exotic-dominated forests on Hawai’i. Forest Ecology and Management 256:593-606.

Liu SG, Anderson P, Zhou GY, Kauffman B, Hughes F, Schimel D, Watson V, Tosi J. 2008. Resolving model parameter values from carbon and nitrogen stock measurements in a wide range of tropical mature forests using nonlinear inversion and regression trees. Ecological Modelling 219:327-341.

Zimmerman N, Hughes RF, Cordell S, Hart P, Chang HK, Perez D, Like RK, Ostertag R. 2008. Patterns of primary succession of native and introduced plants in lowland wet forests in eastern Hawai’i. Biotropica 40:277-284.

LaRosa AM, Tunison JT, Ainsworth A, Kauffman JB, Hughes RF. 2008. Fire and nonnative invasive plants in the Hawaiian bioregion. In: Zouhar K, Smith JK, Brooks M, Sutherland S (eds.) Wildland Fire in Ecosystems: Fire and Nonnative Invasive Plants. Gen. Tech. Rep. RMRS-GTR-42-vol. 6. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Carlson KM, Asner GP, Hughes RF, Ostertag R, Martin RE. 2007. Hyperspectral remote sensing of canopy biodiversity in Hawaiian Lowland Rainforests. Ecosystems 10:536-549.

Hughes RF, Archer SR, Asner GP, Wessman CA, McMurtry C, Nelson J, Ansley RJ. 2006. Changes in aboveground primary production and carbon and nitrogen pools accompanying woody plant encroachment in a temperate savanna. Global Change Biology 12:1733-1747

Hughes RF, Uowolo A. 2006. Impacts of Falcataria moluccana invasion on decomposition in Hawaiian lowland wet forests: The importance of stand-level controls. Ecosystems 9:977-991.

Allison SD, Nielsen C, Hughes RF. 2006. Elevated enzyme activities in soils under the invasive nitrogen-fixing tree Falcataria moluccana. Soil Biology and Biochemistry 38:1537-1544.

Denslow JS, Uowolo A, Hughes RF. 2006. Limitations to seedling establishment in a mesic Hawaiian forest. Oecologia 148:118-128.

Sumida C, Hughes RF, Friday K. 2005. Albizia: The tree that ate Puna. Institute for Pacific Islands Forestry Information Brochure. USDA Forest Service; November 2005.

Elmore AJ, Asner GP, Hughes RF. 2005. Satellite monitoring of vegetation phenology and fire fuel conditions in Hawaiian drylands. Earth Interactions 9:1-21.

Hughes RF, Denslow JS. 2005. Invasion by an N₂-fixing tree, Falcataria moluccana, alters function, composition, and structure of wet lowland forests of Hawai’i. Ecological Applications 15:1615-1628.

Asner GP, Elmore AJ, Hughes RF, Warner AS, Robinson SM, Farrington HM, Vitousek PM. 2005. Ecosystem structure along bioclimatic gradients in Hawai’i from imaging spectroscopy. Remote Sensing of the Environment 96:497-508.

Denslow JS, Hughes RF. 2004. Exotic plants as ecosystem dominants. Weed Technology 18:1283-1287.

Kerr S, Liu S, Pfaff ASP, Hughes RF. 2003. Carbon dynamics and land-use choices: Building a regional-scale multidisciplinary model. Journal of Environmental Management 69: 25-37.

Asner GP, Archer SA, Hughes RF, Ansley RJ, Wessman CA. 2003. Net changes in regional woody vegetation cover and carbon storage in Texas Drylands, 1937-1999. Global Change Biology 9: 316-335.

Cummings DL, Kauffman JB, Perry DA, Hughes RF. 2002. Aboveground biomass and structure of Amazonian Rainforests in Northern Rondônia, Brazil. Forest Ecology and Management 163:293-307.

Hughes RF, Kauffman JB, Cummings DL. 2002. Dynamics of aboveground and soil C and N pools and cycling of available N along a land use gradient in Rondônia, Brazil. Ecosystems 5: 244-259.

Hughes RF, Kauffman JB, Cummings DL. 2002. Fire in the Brazilian Amazon: 3. Biomass, carbon, and nutrient dynamics in slashed second- and third-growth forests. Oecologia 124:574-588.

D’Antonio CM, Hughes RF, Vitousek PM. 2001. Factors influencing dynamics of two invasive C4 grasses in seasonally dry Hawaiian woodlands. Ecology 82:89-104.

Pfaff ASP, Kerr S, Hughes RF, Liu S, Sanchez-Azofeifa GA, Schimel D, Tosi J, Watson V. 2000. The Kyoto Protocol & payments for tropical forest: An interdisciplinary method for estimating carbon-offset supply and increasing the feasibility of a carbon market under the CDM. Ecological Economics 35:203-221.

Hughes RF, Kauffman JB, Jaramillo-Luque VJ. 2000. Ecosystem-scale impacts of deforestation and land use in a humid tropical region of México. Ecological Applications 10:515-527.

Hughes RF, Kauffman JB, Jaramillo-Luque VJ. 1999. Biomass, carbon, and nutrient dynamics of secondary forests in a humid tropical region of México. Ecology 80:1892-1907.

Kauffman JB, Cummings DL, Hughes RF. 1998. Biomass decline in Amazon forest fragments. Science 282:1611.

D’Antonio CM, Hughes RF, Mack MC, Hitchcock D, Vitousek PM. 1998. The response of native species to removal of invasive exotic grasses in a seasonally dry Hawaiian woodland. Journal of Vegetation Science 9:699-712.

Aplet GH, Hughes RF, Vitousek PM. 1998. Ecosystem development on Hawaiian lava flows: Biomass and species composition. Journal of Vegetation Science 9:17-26.

Hughes F, Vitousek PM. 1993. Barriers to shrub re-establishment following fire in the seasonal submontane zone of Hawai’i. Oecologia 93:557-563.

Hughes F, Vitousek PM, Tunison T. 1991. Alien grass invasion and fire in the seasonal submontane zone of Hawai’i. Ecology 72:743-746.

Woodward SA, Vitousek PM, Matson K, Hughes F, Benvenuto K, Matson PA. 1990. Use of the exotic tree Myrica faya by native and exotic birds in Hawai’i Volcanoes National Park. Pacific Science 44:88-93.