Gregory J. Ettl

Biological nitrogen fixation and biomass accumulation within poplar clones as a result of inoculations with diazotrophic endophyte consortia

Sustainable production of biomass for bioenergy relies on low-input crop production. Inoculation of bioenergy crops with plant growth-promoting endophytes has the potential to reduce fertilizer inputs through the enhancement of biological nitrogen fixation (BNF). Endophytes isolated from native poplar growing in nutrient-poor conditions were selected for a series of glasshouse and field trials designed to test the overall hypothesis that naturally occurring diazotrophic endophytes impart growth promotion of the host plants. Endophyte inoculations contributed to increased biomass over uninoculated control plants. This growth promotion was more pronounced with multi-strain consortia than with single-strain inocula. Biological nitrogen fixation was estimated through (15)N isotope dilution to be 65% nitrogen derived from air (Ndfa). Phenotypic plasticity in biomass allocation and branch production observed as a result of endophyte inoculations may be useful in bioenergy crop breeding and engineering programs.

Effects of cross host species inoculation of nitrogen- fixing endophytes on growth and leaf physiology of maize

Plants that grow and thrive under abiotic stress often do so with the help of endophytic microorganisms. Although nitrogen‐fixing (diazotrophic) endophytes colonize many wild plants, these natural relationships may be disrupted in cultivated crop species where breeding and genotype selection often occur under conditions of intensive fertilization and irrigation. Many energy crops including corn may still benefit from diazotrophic endophyte inoculations allowing for more efficient biomass production with less input of petroleum‐derived fertilizer. A selection of diazotrophic endophytes isolated from willow (Salix sitchensis, Sitka willow) and poplar (Populus trichocarpa, black cottonwood) growing in nutrient‐poor river sides were used as inoculum in three experiments testing the effect on plant growth and leaf level physiology of a sweet corn variety under various levels of applied nitrogen fertilizer. We report substantial growth promotion with improved leaf physiology of corn plants in response to diazotrophic endophyte inoculations. Significant gains of early biomass with a greater root : shoot ratio were found for plants receiving endophytic inocula over the uninoculated control groups regardless of the nitrogen level. Furthermore, inoculated plants exhibited consistently higher rates of net CO2 assimilation than did those without endophytic inoculation. These results have beneficial implications for enhanced plant growth in a low‐input system on nutrient‐poor sites. The immediate increase of root mass observed in endophyte inoculated plants has the potential to provide better establishment and early growth in resource‐limited environments. The initial results of this study also indicate that the beneficial effect from endophytes isolated from poplar and willow species is not restricted to the species from which they were initially isolated.

The Effect of Forest Management Strategy on Carbon Storage and Revenue in Western Washington: A Probabilistic Simulation of Tradeoffs

The objectives of this study are to understand tradeoffs between forest carbon and timber values, and evaluate the impact of uncertainty in improved forest management (IFM) carbon offset projects to improve forest management decisions. The study uses probabilistic simulation of uncertainty in financial risk for three management scenarios (clearcutting in 45- and 65-year rotations and no harvest) under three carbon price schemes (historic voluntary market prices, cap and trade, and carbon prices set to equal net present value (NPV) from timber-oriented management). Uncertainty is modeled for value and amount of carbon credits and wood products, the accuracy of forest growth model forecasts, and four other variables relevant to American Carbon Registry methodology. Calculations use forest inventory data from a 1,740 ha forest in western Washington State, using the Forest Vegetation Simulator (FVS) growth model. Sensitivity analysis shows that FVS model uncertainty contributes more than 70% to overall NPV variance, followed in importance by variability in inventory sample (3-14%), and short-term prices for timber products (8%), while variability in carbon credit price has little influence (1.1%). At regional average land-holding costs, a no-harvest management scenario would become revenue-positive at a carbon credit break-point price of

Auctioning the Forest: A Qualitative Approach to Exploring Stakeholder Responses to Bidding on Forest Ecosystem Services

14.17/Mg carbon dioxide equivalent (CO2 e). IFM carbon projects are associated with a greater chance of both large payouts and large losses to landowners. These results inform policymakers and forest owners of the carbon credit price necessary for IFM approaches to equal or better the business-as-usual strategy, while highlighting the magnitude of financial risk and reward through probabilistic simulation.

The Deniable Truth of Sustainable Forestry

The loss of private forestland diminishes ecosystems, including wildlife habitat, carbon sequestration and clean water. The emergence of new markets for forest ecosystem services offers one solution for private forestland financing while having the potential to increase the provision of forest ecosystem services. The general public’s willingness to participate in an auction mechanism for private forest ecosystem services was assessed for a regionally representative forest in Washington State using focus group methodology. The auction mechanism utilizes cost-effective management scenarios that stakeholders competitively bid on. Participants exhibited preferences for specific management plans while also making trade-offs in order to ensure that a plan would win. Participants expressed clear preferences for recreational access, mature forest habitat, aesthetic amenities, and improved water quality. Participants were receptive to the auction mechanism while maintaining concerns over viability, transparency, and local stakeholder involvement.

Growth responses of subalpine fir to climatic variability in the Pacific Northwest

Email: ettl@uw.edu Let’s start with the deniable truth—at present sustainable forestry is rare or localized. This is apparent when looking at global scales but also at regional and local scales. Globally, deforestation and land conversion continue. There is less forest each year (-5.2 million ha yr-1), and conversion of frontier (primary, or ancient) forests to second growth forests of shorter rotations of non-native species and lower tree diversity is common (-40 million ha 2000-2010, FAO 2010). The extraction of historic timber has been used to build economies from one part of the planet to another. This is deniable because in a global economy, timber use and extraction are often disconnected. Deniable because we have defined sustainable forestry so broadly that we can all agree that it is “good” without having a common understanding of the term. Finally, deniable because forestry operates on rotations that exceed human life experiences and expectancies, meaning any collapse of a system comes long after generations who initiated the process.