Lloyd L. Nackley

Bioenergy that supports ecological restoration.

Bioenergy development can offer beneficial ecological and economic synergies through the expansion of ecological restoration projects. Such synergies are demonstrated by means of a case study conducted in central Washington State, where a 52.4-ha ecological restoration site on the Yakama Reservation generated 34 mega-grams (Mg) of invasive tree biomass per hectare, costing

A salt on the bioenergy and biological invasions debate: salinity tolerance of the invasive biomass feedstock Arundo donax

988 ha−1. A geospatial model of transportation costs estimated that extracted invasive tree biomass can generate revenues throughout 1103 803 ha when delivered to a proposed bioenergy facility in White Swan, Washington, providing 53 000–180 000 Mg of biomass per year for several decades. Thermochemical analyses revealed that the elevated nitrogen, sulfur, and ash content in two prolific invasive trees – Russian olive (Elaeagnus angustifolia) and salt cedar (Tamarix spp) – will limit demand for either of these invasive species. We compare our regional data to national estimates, and show the broader potential for expanding ecological restoration activities and biomass supplies through the revenues generated by the sale of invasive tree wood-waste into bioenergy markets.

Investigating the impacts of recycled water on long-lived conifers

Arundo donax L., commonly known as giant reed, is promising biomass feedstock that is also a notorious invasive plant in freshwater ecosystems around the world. Heretofore, the salt tolerance of A. donax had not been quantified even though anecdotal evidence suggests halophytic qualities. To test whole‐plant and leaf level responses, we established a pot experiment on 80 scions propagated from an A. donax population that has naturalized on the shore of the San Francisco Bay Estuary. To quantify growth and physiological responses to salinity (NaCl), A. donax scions were divided into eight treatments and grown for 60 days across a range of salinities (0–42 dS m−1). Classic growth analysis showed >80% reduction in overall growth at the highest salinities. Yet, there was zero mortality indicating that A. donax is able to tolerate high levels of salt. Declining photosynthesis rates were strongly correlated (R2 > 0.97) with decreasing stomatal conductance, which was in turn closely related to increasing salinity. Leaf gas exchange revealed that stomata and leaf limitations of carbon dioxide were three times greater at high salinities. Nonetheless, even when salinities were 38–42 dS m−1 A. donax was able to maintain assimilation rates 7–12 μmol m−2 s−1. Further, by maintaining 50% relative growth at salinities ~12 dS m−1 A. donax can now be classified as ‘moderately salt tolerant’. A. donax leaf gas exchange and whole‐plant salt tolerance are greater than many important food crops (i.e. maize, rice), the bioenergy feedstock Miscanthus × giganteus, as well as some uncultivated plant species (i.e. Populus and Salix) that are indigenous in regions A. donax currently invades. The results of this study have implications for both agronomists wishing to expand A. donax to fields dominated by saline soils, and for others who are concerned about the spread of A. donax with altered stream hydrology or sea‐level rise.

Conservation Efforts, Contemporary

This research has direct implications for public and private institutions seeking to conserve water by irrigating landscapes with recycled (a.k.a. reclaimed) water. Although typical salt contents in recycled water are low (< 2.0 dS m−1), levels may still be harmful to salt-sensitive plants. We discovered that salt accumulation in soils would negatively impact coast redwoods when recycled water salinity exceeds>1.0 dS m−1. This is the first paper reporting the impacts of salinity on the growth of the coast redwood. The results suggest that irrigation management of long-lived conifers will be essential to protect these important trees.

Arundo donax water use and photosynthetic responses to drought and elevated CO2

This article presents many current issues and challenges involved with converting theories from the natural sciences, into practical applications for biological conservation in societies where resource supplies are finite. Two philosophical changes diverging from historical conservation theories have created the most problems for implementing current conservation strategies. The first has been the shifting emphasis of scientific inquiry from the species to the ecosystem level. This has triggered the re-evaluation of species based theories, and management, when translated to ecosystem scale applications. The second change has been the recognition that humans are an integral part of most ecosystems, and will likely influence the success of most conservation projects. The approach used by conservation managers to include humans into a conservation project has varied depending on how industrialized a country is and how dependent society is on extracting the resources to develop their economies from lands delivering conservation services. In less industrialized countries, conservation projects are linked to economic development strategies because local communities are dependent upon collecting resources from lands designated for conservation. In highly industrialized countries, the conservation tools and approaches have focused on restoring species and habitats, and developing models as decision-making tools at the landscape scale.