@article{shifflett_culbreth_hazel_daniels_nichols_2016, title={Coupling aquaculture with forest plantations for food, energy, and water resiliency}, volume={571}, ISSN={0048-9697}, url={http://dx.doi.org/10.1016/j.scitotenv.2016.07.161}, DOI={10.1016/j.scitotenv.2016.07.161}, abstractNote={Freshwater aquaculture and forest bioenergy markets are expanding globally in areas concurrently experiencing human population growth, urbanization and water shortages. Coupling these agroecosystems can improve food, energy, and water resiliency by enhancing ecosystem services through fertilization, water-reuse, carbon storage, and bioenergy via biomass production. This study evaluated how a model aquaculture-managed forest plantation could (1) provision fish and woody biomass; (2) regulate carbon, groundwater infiltration, and groundwater quality; and (3) support nutrient cycling over a two-year period. A 0.5-hectare hardwood bioenergy plantation was established with 12 Populus spp. genotypes adjacent to a 0.6-hectare freshwater aquaculture operation (hybrid striped bass, Morone chrysops×M. saxatilis); pond waters were land-applied on the plantation for two years. The aquaculture operation produced ~3.5Mg of fish and trees yielded 5.9Mgha(-1)yr(-1) of oven-dry biomass, sequestered 2.9Mg carbon (C) ha(-1)yr(-1) and stored 0.028Mg nitrogen (N) ha(-1)yr(-1). Biomass productivity, carbon storage, and nitrogen storage differed significantly among the evaluated Populus genotypes. Land application of pond water increased groundwater infiltration by 60% relative to the previous year. The integrated system regulated chlorophyll a, total organic carbon, and nitrogen in groundwater at concentrations below regulatory limits. This study demonstrated that coupled agroecosystems could deliver productive yields of food and bioenergy as well as support water re-use while meeting water quality regulations. More research is needed to evaluated long-term sustainability and economic viability of this coupled system and other land management practices that seek to improve food, energy, and water resiliency.}, journal={Science of The Total Environment}, publisher={Elsevier BV}, author={Shifflett, Shawn Dayson and Culbreth, Allison and Hazel, Dennis and Daniels, Harry and Nichols, Elizabeth Guthrie}, year={2016}, month={Nov}, pages={1262–1270} }
 @article{birch_emanuel_james_nichols_2016, title={Hydrologic Impacts of Municipal Wastewater Irrigation to a Temperate Forest Watershed}, volume={45}, ISSN={0047-2425}, url={http://dx.doi.org/10.2134/jeq2015.11.0577}, DOI={10.2134/jeq2015.11.0577}, abstractNote={Land application of municipal wastewater to managed forests is an important treatment and water reuse technology used globally, but the hydrological processes of these systems are not well characterized for temperate areas with annual rainfall of 1200 mm or greater. This study evaluated the impact of municipal wastewater irrigation to the local water balance at a 3000‐ha land application facility where secondary‐treated wastewater is land applied to a mixed hardwood–pine forest over 900 ha. Stable isotopes of hydrogen (2H) and oxygen (18O), chloride concentrations, and specific conductance were used in combination with hydrometric measurements to estimate the wastewater composition in groundwater, surface water, and at the watershed outlet during dry and wet seasonal periods and during one large rainfall event. Wastewater and water bodies receiving irrigation were found to have significantly higher δ2H, δ18O, specific conductance, and chloride concentrations. Using these tracers, a two‐component, three‐end member geochemical mixing model estimated mean wastewater compositions in the surficial aquifer receiving irrigation from 47 to 73%. Surface water onsite was found to reflect the high wastewater composition in groundwater. Land‐applied wastewater contributed an estimated 24% of total streamflow, with the highest wastewater compositions in surface water observed during major storm events and at low‐flow conditions. Groundwater and surface water within the watershed were found to have proportionally higher wastewater compositions than expected based on the proportion of irrigation to rainfall received by these areas.}, number={4}, journal={Journal of Environmental Quality}, publisher={Wiley}, author={Birch, Andrew L. and Emanuel, Ryan E. and James, April L. and Nichols, Elizabeth Guthrie}, year={2016}, month={Jul}, pages={1303–1312} }
 @article{shifflett_hazel_guthrie nichols_2016, title={Sub-Soiling and Genotype Selection Improves Populus Productivity Grown on a North Carolina Sandy Soil}, volume={7}, ISSN={1999-4907}, url={http://dx.doi.org/10.3390/f7040074}, DOI={10.3390/f7040074}, abstractNote={This study reports the stem volume of 10 Populus genotypes in a randomized split-plot design with different tillage treatments (disking versus sub-soiling) after two years of growth. Height, diameter at breast height (DBH), stem aboveground volume index, survival, Melampsora rust resistance, leaf area index (LAI), chlorophyll content, and foliar nitrogen concentration (Foliar N) were measured to identify how tillage treatments might alter poplar growth. Stem volume index and LAI were positively correlated and differed significantly among tillage treatments, taxa, and genotypes. Melampsora rust resistance was also positively correlated with volume index, but significant differences were only detected among taxa and genotypes. Foliar N and chlorophyll did not correlate to stem volume for genotypes or tillage treatments. Overall, sub-soiling yielded 37% more estimated volume compared to disking. Within the sub-soiled treatments, four genotypes (140, 176, 185, and 356) had high survival (>80%) and produced substantial stem volume (>32 dm3·tree−1). These findings show that tillage practices do impact poplar stem volumes after two years and that sub-soiling improves productivity for poplar short rotation woody crops on loamy fine-sandy soils.}, number={12}, journal={Forests}, publisher={MDPI AG}, author={Shifflett, Shawn and Hazel, Dennis and Guthrie Nichols, Elizabeth}, year={2016}, month={Mar}, pages={74} }
 @article{ghezehei_shifflett_hazel_nichols_2015, title={SRWC bioenergy productivity and economic feasibility on marginal lands}, volume={160}, ISSN={["1095-8630"]}, DOI={10.1016/j.jenvman.2015.05.025}, abstractNote={Evolving bioenergy markets necessitate consideration of marginal lands for woody biomass production worldwide particularly the southeastern U.S., a prominent wood pellet exporter to Europe. Growing short rotation woody crops (SRWCs) on marginal lands minimizes concerns about using croplands for bioenergy production and reinforces sustainability of wood supply to existing and growing global biomass markets. We estimated mean annual aboveground green biomass increments (MAIs) and assessed economic feasibility of various operationally established (0.5 ha-109 ha) SRWC stands on lands used to mitigate environmental liabilities of municipal wastewater, livestock wastewater and sludge, and subsurface contamination by petroleum and pesticides. MAIs (Mg ha(-1) yr(-1)) had no consistent relationship with stand density or age. Non-irrigated Populus, Plantanus occidentalis L. and Pinus taeda L. stands produced 2.4-12.4 Mg ha(-1) yr(-1). Older, irrigated Taxodium distchum L., Fraxinus pennsylvanica L., and coppiced P. occidentalis stands had higher MAIs (10.6-21.3 Mg ha(-1) yr(-1)) than irrigated Liquidambar styraciflua L. and non-coppiced, irrigated P. occidentalis (8-18 Mg ha(-1) yr(-1)). Natural hardwood MAIs at 20-60 years were less than hardwood and P. taeda productivities at 5-20 years. Unlike weed control, irrigation and coppicing improved managed hardwood productivity. Rotation length affected economic outcomes although the returns were poor due to high establishment and maintenance costs, low productivities and low current stumpage values, which are expected to quickly change with development of robust global markets.}, journal={JOURNAL OF ENVIRONMENTAL MANAGEMENT}, publisher={Elsevier BV}, author={Ghezehei, Solomon B. and Shifflett, Shawn D. and Hazel, Dennis W. and Nichols, Elizabeth Guthrie}, year={2015}, month={Sep}, pages={57–66} }
 @article{shifflett_hazel_frederick_nichols_2013, title={Species Trials of Short Rotation Woody Crops on Two Wastewater Application Sites in North Carolina, USA}, volume={7}, ISSN={1939-1234 1939-1242}, url={http://dx.doi.org/10.1007/s12155-013-9351-2}, DOI={10.1007/s12155-013-9351-2}, number={1}, journal={BioEnergy Research}, publisher={Springer Science and Business Media LLC}, author={Shifflett, Shawn Dayson and Hazel, Dennis W and Frederick, Douglas J and Nichols, Elizabeth Guthrie}, year={2013}, month={Jul}, pages={157–173} }