@article{li_minick_li_williamson_gavazzi_mcnulty_king_2020, title={An improved method for quantifying total fine root decomposition in plantation forests combining measurements of soil coring and minirhizotrons with a mass balance model}, volume={40}, ISSN={["1758-4469"]}, DOI={10.1093/treephys/tpaa074}, abstractNote={Accurate measurement of total fine root decomposition (the amount of dead fine roots decomposed per unit soil volume) is essential for constructing a soil carbon (C) budget. However, the ingrowth/soil core-based models are dependent on the assumptions that fine roots in litterbags/intact cores have the same relative decomposition rate as those in intact soils and that fine root growth and death rates remain constant over time, while minirhizotrons cannot quantify the total fine root decomposition. To improve the accuracy of estimates for total fine root decomposition, we propose a new method (Balanced-hybrid) with two models that integrates measurements of soil coring and minirhizotrons into a mass balance model. Model input parameters were fine root biomass, necromass, and turnover rate for Model 1 and fine root biomass, necromass, and death rate for Model 2. We tested the Balanced-hybrid method in a loblolly pine plantation forest in coastal North Carolina, USA. The total decomposition rate of absorptive fine roots (ARs) (a combination of first and second-order fine roots) using Model 1 and Model 2 was107 ± 13 g m-2 year-1 and 129 ± 12 g m-2 year-1, respectively. Monthly total AR decomposition was highest from August to November, which corresponded with the highest monthly total ARs mortality. ARs imaged by minirhizotrons well represent those growing in intact soils, evident by a significant and positive relationship between the standing biomass and the standing length. The total decomposition estimate in both models was sensitive to changes in fine root biomass, turnover rate, and death rate but not to change in necromass. Compared with Model 2, Model 1 can avoid the technical difficulty of deciding dead time of individual fine roots but requires greater time and effort to accurately measure fine root biomass dynamics. The Balanced-hybrid method is an improved technique for measuring total fine root decomposition in plantation forests in which the estimates are based on empirical data from soil coring and minirhizotrons, moving beyond assumptions of traditional approaches.}, number={10}, journal={TREE PHYSIOLOGY}, author={Li, Xuefeng and Minick, Kevan J. and Li, Tonghua and Williamson, James C. and Gavazzi, Michael and McNulty, Steven and King, John S.}, year={2020}, month={Oct}, pages={1466–1473} }
 @article{fischer_kelley_ward_boone_ashley_domec_williamson_king_2017, title={A critical analysis of species selection and high vs. low-input silviculture on establishment success and early productivity of model short-rotation wood-energy cropping systems}, volume={98}, ISSN={["1873-2909"]}, DOI={10.1016/j.biombioe.2017.01.027}, abstractNote={Most research on bioenergy short rotation woody crops (SRWC) has been dedicated to the genera Populus and Salix. These species generally require relatively high-input culture, including intensive weed competition control, which increases costs and environmental externalities. Widespread native early successional species, characterized by high productivity and good coppicing ability, may be better adapted to local environmental stresses and therefore could offer alternative low-input bioenergy production systems. To test this concept, we established a three-year experiment comparing a widely-used hybrid poplar (Populus nigra × P. maximowiczii, clone ‘NM6’) to two native species, American sycamore (Platanus occidentalis L.) and tuliptree (Liriodendron tulipifera L.) grown under contrasting weed and pest control at a coastal plain site in eastern North Carolina, USA. Mean cumulative aboveground wood production was significantly greater in sycamore, with yields of 46.6 Mg ha−1 under high-inputs and 32.7 Mg ha−1 under low-input culture, which rivaled the high-input NM6 yield of 32.9 Mg ha−1. NM6 under low-input management provided noncompetitive yield of 6.2 Mg ha−1. Sycamore also showed superiority in survival, biomass increment, weed resistance, treatment convergence, and within-stand uniformity. All are important characteristics for a bioenergy feedstock crop species, leading to reliable establishment and efficient biomass production. Poor performance in all traits was found for tuliptree, with a maximum yield of 1.2 Mg ha−1, suggesting this native species is a poor choice for SRWC. We conclude that careful species selection beyond the conventionally used genera may enhance reliability and decrease negative environmental impacts of the bioenergy biomass production sector.}, journal={BIOMASS & BIOENERGY}, author={Fischer, M. and Kelley, A. M. and Ward, E. J. and Boone, J. D. and Ashley, E. M. and Domec, J. -C. and Williamson, J. C. and King, J. S.}, year={2017}, month={Mar}, pages={214–227} }
 @article{domec_ashley_fischer_noormets_boone_williamson_king_2017, title={Productivity, Biomass Partitioning, and Energy Yield of Low-Input Short-Rotation American Sycamore (Platanus occidentalis L.) Grown on Marginal Land: Effects of Planting Density and Simulated Drought}, volume={10}, ISSN={["1939-1242"]}, DOI={10.1007/s12155-017-9852-5}, number={3}, journal={BIOENERGY RESEARCH}, author={Domec, Jean-Christophe and Ashley, Elissa and Fischer, Milan and Noormets, Asko and Boone, Jameson and Williamson, James C. and King, John S.}, year={2017}, month={Sep}, pages={903–914} }