Ecophysiology as a tool for evaluating invasive-plant based bioenergies: physiological and ecological case-studies of Arundo donax and Elaeagnus angustifolia
Thesis (Ph.D.)--University of Washington, 2012In recent years, environmental and social pressures have fostered the development of biomass based energies. Development of `ideal' biomass feedstocks has led to characterizations of physiological traits that are similar to many of the physiological traits that typify number of invasive grasses. This has led to controversy about the sustainable implementation of invasive-grass based bioenergy feedstocks. While the debate has continued for much of the past decade, little work has been published quantifying the arguments on either side of the controversy. The work presented herein addresses the lack of evidence regarding the potential for increasing plant invasions by utilizing known invasive plants as biomass feedstocks. The first three chapters deal specifically with the invasive grass species Arundo donax. These chapters describe experiments in which A. donax was grown under a variety of treatments which have been predicted as potential environmental alterations associated with global climate change such as: carbon dioxide enrichment, drought, resource limitations, and soil salinization. The effects of these treatments were quantified at the whole-plant and leaf-level scales. Results show thatA. donax is able to persist and grow in environmental conditions that typically limit growth of most crops and some native plant species. Furthermore, its growth was found to be improved under elevated carbon dioxide. These findings suggest that it is unlikely A. donax will be constrained by the agricultural setting, and therefore cultivating it will disperse it to new environments and will likely lead to future invasions. Alternatively, this dissertation addresses the potential for bioenergy markets to help reduce the spread of invasive plants by partnering with on-going ecological restoration. In the last chapter of the dissertation, titled Bioenergy that Supports Ecological Restoration, a case-study experiment in central Washington State reveals how wood-waste for ecological restoration of Russian olive (Elaeagnus angustifolia) can be converted into bioenergy. These findings suggest that a restoration costs can be offset from the sale of Russian olive wood for bioenergy. Yet, the quality of the Russian olive wood is divergent from the typical biomass resources which will limit its incorporation into the bioenergy market. The Russian olive findings present the first supply and demand analysis of invasive plant biomass for bioenergy
