People - Students - Lloyd Nackley

Lloyd Nackley 

Education: BS, Environmental Horticultural Science 2003 California State Polytechnic University

Major: Forest Resources

Advisors: Kristiina Vogt and Sarah Reichard

Major Research Project: An Ecological Risk Assessment of Giant Reed, Arundo donax, as a Feedstock for Cellulosic Biofuel Production.

Context of Research: Giant reed (Arundo donax) is a grass (Poaceae) resembling sugar cane or bamboo, and is a noxious weed, in many watersheds, outside of its native range (Eurasia). Giant reed reduces native vegetation, reduces habitat for native fauna, reduces the ecosystem biodiversity, and may increase fire frequency and intensity. Giant Reed is also being developed as a biofuel feedstock in North America and Europe, because it displays many beneficial attributes as an energy crop. Like other perennial, rhizomatous grasses Arundo donax is attractive for biomass production, because of its high yield, efficient water-use, high contents of lignin and cellulose, low water content, low nutrient requirements, few pests or diseases, the limited need for soil tillage (restricted to the year which the crops are established), rapid growth and long canopy duration (to outcompete weeds), and Arundo is sterile. However, Arundo donax was selected to fulfill the demands of bioenergy production based on the high biomass yields and appropriate biomass characteristics (Lewandowski et al. 2003), without regard to environmental risks associated with non-native plant invasions into surrounding native plant communities. Other than sterility, the characteristics which make Arundo as an ideal biofuel crop also typify much of our invasive flora (Barney and DiTomaso 2008). Furthermore, cultivation of Arundo donax increases the likeliness of establishment by increasing number of plants, which are potential propagule sources; the unnatural populations are able to overcome biotic and abiotic stressors by sheer force of numbers (Lockwood et al. 2005). The indications, of a potential biological invasion by Arundo donax, call for the need of a thorough ecological analysis and risk assessment.

Research Plan: Risk assessment of Arundo donax as a biofuel source is an estimation of probabilities and magnitudes of a biological invasion into native ecosystems. An ecological risk assessment evaluates the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors and is developed within a risk management context to evaluate human-induced changes that are considered undesirable (EPA 1998). Four approaches recommend by the Ecological Society of America are: environment matching; consideration of propagule pressure; analysis based on the traits of species; and expert opinion (Lodge et al. 2006).

Along these guidelines, my research will develop:

• A species distribution model, a spatially explicit statistical and empirical model of species distribution (Guisan and Thuiller 2005), which are based on ecological niches and may be used with high predictive accuracy to assess potential biological invasions (Peterson 2003).
• Quantitative estimation of propagule pressure appropriate to the scale of the proposed cultivation.
• The Australian Weed Risk Assessment (WRA) (Pheloung 1999) is commonly used model for evaluating invasive potential based on traits of species. I will use bootstrapping and Bayesian statistical techniques (Caley et al.2006) to quantify the uncertainty of the WRA and thereby better enable managers to make decisions regarding risk.

Broader Impacts of Research: It has been shown in other cases that risk assessments for invasive species produce net bio-economic benefits (Keller et al. 2007). My research will provide valuable ecological and economic assessments and will be useful data for future life-cycle assessments of cellulosic biofuels.

Reference:

Barney, J. N. and J.M. Ditomaso (2008). "Nonnative species and bioenergy: Are we cultivating the next invader?" Bioscience 58 (1): 64-70.

Caley, P., W.M. Lonsdale, et al. (2006). "Quantifying uncertainty in predictions of invasiveness, with emphasis on weed reisk assessment." Biological Invasions 8 (8): 1595-1604.

Guisan, A. and W. Thuiller (2005). "Predicting species distribution: offering more than simple habitat models." Ecology Letters 8 (9): 993-1009.

Keller, R. P., D.M. Lodge, et al. (2007). "Risk assessment for invasive species produces net bioeconomic benefits." Proceedings of the National Academy of Sciences of the United States of America 104 (1): 203-207

Lockwood, J. L., P. Cassey, et al. (2005). "The role of propagule pressure in explaining species invasions." Trends in Ecology & Evolution 20 (5): 223-228.

Lodge, D. M., S. Williams, et al. (2006). "Biological Invasions: Recommendations for U.S. Policy and Management." Ecological Applications 16 (6): 2035-2054

Pheloung, P.C., P.A. Williams, et al. (1999). "A weed risk assessment model for use as a biosecurity tool evaluating plant introductions." Journal of Environmental Management 57 (4): 239-251

Peterson, A. T. (2003). "Predicting the Geography of Species’ Invasions Via Ecological Niche Modeling." Quarterly Review of Biology 78 (4): 419-433.

U.S. Environmental Protection Agency (EPA), (1998). "Guidelines for Ecological Risk Assessment", Risk Assessment Forum, EPA/630/R-95/002F, Washington D.C.