Conserve and Enhance Feedstocks for Bioenergy

Two recent issues have reinvigorated bioenergy research activity within the Northern Research Station. One is the groundswell of interest in mitigating global climate change by reducing atmospheric carbon dioxide (CO₂) accumulation. Bioenergy from harvested wood results in “no net accumulation” because the CO₂ released is re-cycled back into the new forests that grows back to replace the harvested one. Second is the increasing cost and threats to national security associated with crude oil imports. The Northern Research Station (NRS) has worked with the U.S. Department of Energy since the first OPEC oil embargo in 1973.

Research Studies

An Approach for Siting Poplar Energy Production Systems to Increase Productivity and Associated Ecosystem Services
Highly productive poplars grown primarily on marginal agricultural sites are an important component of our future Midwest energy portfolio. Additionally, poplars can be strategically placed in the landscape to conserve soil and water, recycle nutrients, and sequester carbon. These purpose-grown trees are vital to reducing our dependence on non-renewable and foreign sources of energy used for heat and power. Establishing poplar genotypes that are adapted to local environmental conditions substantially increases establishment success and productivity. But, it is difficult to predict field trial success in landscapes where the crop has not been previously deployed.

Predicting and Mapping Biomass of Poplar Energy Crops in the North Central United States
Populus species and hybrids (i.e., poplars) have demonstrated high yield potential in the North Central United States as short-rotation woody crops (SRWCs). However, the ability to predict biomass yields for sites not currently in SRWCs is limited. As a result, stakeholders are also limited in their ability to evaluate different areas within the region as potential supply sheds for wood-based bioenergy facilities. A reliable method for predicting biomass productivity across the region is needed; preferably, such a method will also lend itself to generating yield maps that stakeholders can readily use to inform their decision-making processes.

Biomass for Energy Production
NRS scientists are exploring current and future woody biomass availability from multiple perspectives including estimation of available wood residues from harvest operations in native forests, options for plantation production of woody biomass, biomass resources in proximity to coal-fired electricity plants that have the capacity to co-fire with wood, the apparent effects of policies related to utilization of biomass for energy, factors affecting utilization of woody for residential heating, and long-term effects of intensive biomass on forest soil nutrients. 

Renewable Energy: Woody Biomass Utilization
Renewable energy sources are the focal point of major federal and state initiatives to establish energy self-sufficiency in the United States.  While wind, solar, and hydroelectric power projects have garnered most of the past attention in the renewable energy dialogue, the contribution and growth of the corn-based ethanol industry has helped policy makers to focus attention on the largely-overlooked biomass energy potential in North America. 

Genetics and Genotype × Environment Interactions Affecting Adventitious Rooting and Early Establishment of Poplar Energy Crops
Gaining knowledge about the genetics and genotype × environment interactions affecting adventitious rooting is important for energy crop production. First, rapid and extensive rooting reduces establishment costs by permitting the use of unrooted cuttings as commercial stock rather than rooted cuttings. Second, assuming concomitant and well-balanced shoot development, rapid and extensive rooting promotes early growth, reducing vegetation management costs and the time period to crown closure. Third, rapid and extensive rooting that is stable in the face of varying environmental conditions can increase the period of time during which successful planting can occur, increasing operational flexibility.  

Impacts of harvesting forest residues for bioenergy on nutrient cycling and community assemblages in northern hardwood forests
The increasing demand to utilize slash for bioenergy purposes will compete with other ecological services forests provide.  Current site-level guidelines emphasize retaining large diameter coarse woody debris (CWD) based on many studies documenting the important role it plays in managing biodiversity and contributing to nutrient cycling.   However, little information exists to help guide land managers on appropriate levels of fine woody debris (<6 inch diameter) retention for biodiversity and nutrient cycling concerns. 

Phyto-Recurrent Selection: A Method for Selecting Genotypes for Phytotechnologies
The success of certain phytotechnologies has prompted the use of wastewaters as a combination of irrigation and fertilization for woody crops such Populus species and their hybrids (i.e., poplars). A common protocol for such efforts has been to utilize a limited number of readily-available genotypes with decades of deployment in other applications, such as fiber or windbreaks. However, it is possible to increase phytoremediation success with proper genotypic screening and selection, followed by the field establishment of clones that exhibited favorable potential for clean-up of specific contaminants. While such efforts are limited for environmental remediation, centuries of plant selection success in agronomy, horticulture, and forestry validate the need for similar approaches in phytotechnologies. 

Breeding and Selecting Poplar for Biofuels, Bioenergy, and Bioproducts
Hybridization of poplars occurs naturally among certain taxonomic sections, as well as from planned breeding efforts. Given that most of the variability of poplars is at the species level, both intra- and inter-specific hybridization have been vital tools for producing progeny that outperform either or both parents for biologically and economically important traits. It is important to refine breeding, testing, and selection protocols so that new, superior poplar genotypes can replace their underperforming counterparts.

Enhanced Adaptation to Climate Change of Conifer Species and Provenances in Northern Forest Ecosystems
Over 12 million trees were distributed from Wisconsin state forest nurseries in 2007. The success of such regeneration programs depends upon the development of adaptation strategies for enhanced ecosystem sustainability under changing climates. There is a need to identify species and seed sources with enhanced adaptation to climate change pressures to ensure biologically and economically sustainable reforestation, afforestation, and gene conservation.

Salt Tolerance and Salinity Thresholds of Woody Energy Crops Irrigated with High-salinity Waste Waters
There is a need for environmental practices that merge intensive forestry with waste management. Producing short rotation woody crops for energy, fiber, and environmental benefits requires adequate irrigation and fertilization, which can be supplied via waste waters including landfill leachate. Yet, leachate often contains elevated levels of salts such as chloride and sodium that cause leaf chlorosis and necrosis, decreased biomass accumulation, and increased mortality. Therefore, there is a pressing need to learn about the response of poplar energy crops when salts are taken up into root, leaf, and woody (stem + branch) tissues, as well as identifying thresholds of salt concentrations and salinity that can be recommended for these crops in both field testing and production plantations.

Carbon Implications of Poplar Energy Crops Throughout the Energy Supply Chain

Woody production systems and conversion technologies are needed to: maintain healthy forests and ecosystems, create high paying manufacturing jobs, and meet local/regional energy demands. Poplars are dedicated energy crops that can be strategically placed in the landscape to conserve soil and water, recycle nutrients, and sequester carbon. However, key environmental and economic uncertainties preclude broad-scale production of biofuels/bioproducts from poplar wood. Therefore, building on decades of research conducted at our Institute and throughout the region, we are evaluating the fate of carbon in soils and woody biomass, soil greenhouse gas emissions, and conversion efficiency barriers throughout the energy supply chain.

Technical Innovations to Reduce Impacts of Invasive Species
Technology that is available to manage invasive species and increase productivity of short rotation woody crops (SRWC) is often too expensive, difficult to operate, cumbersome, and/or impractical. There is a need for technical innovations that help to achieve these objectives while meeting specific experimental needs.

Comprehensive Database of North American Poplar Research Published from 1989 to 2011
In addition to compiling the information into one interactive location, our objectives are to encourage publication in peer-reviewed journals and to enhance collaborations with partners outside the poplar community. The constraints of the database include: only peer-reviewed manuscripts that are focused on poplars, cottonwoods, aspens, and their hybrids grown as short rotation woody crops, research conducted in North America, and at least one topic area.

Biofuels, Bioenergy, and Bioproducts from Short Rotation Woody Crops
We are testing the genetics, physiology, and silviculture of poplar crops. Specific areas of interest include quantitative genetic analyses of biomass, rooting, and other important traits from hundreds of genotypes grown throughout the North Central United States, as well as analyses of tree growth regulating mechanisms in the face of varying environments and changing climate. Our silviculture research includes a range of studies from vegetation management to yield trials.

Sustainable Production of Woody Energy Crops with Associated Environmental Benefits
Increasing human population levels at regional, national, and global scales have heightened the need for proper management of residential and industrial waste. Contaminants from this waste stream have polluted water, air, and soil much faster than traditional technologies could remediate the problem. Therefore, we are combining intensive forestry and waste management methods to increase the potential for producing woody crops for energy and fiber, along with decreasing the environmental degradation associated with waste disposal and subsequent waste water production.