@article{minick_aguilos_li_mitra_prajapati_king_2022, title={Effects of Spatial Variability and Drainage on Extracellular Enzyme Activity in Coastal Freshwater Forested Wetlands of Eastern North Carolina, USA}, volume={13}, ISSN={1999-4907}, url={http://dx.doi.org/10.3390/f13060861}, DOI={10.3390/f13060861}, abstractNote={Drainage of freshwater wetlands is common in coastal regions, although the effects on microbial extracellular enzyme activity (a key mediator of soil organic matter decomposition) in relation to spatial variability (microtopography and soil depth) are poorly understood. Soils were collected from organic (Oi, Oe, Oa) and mineral (A, AB, B) horizons from a natural and drained coastal forested wetland in North Carolina, USA. Activity of seven enzymes were measured: α-glucosidase (AG), β-glucosidase (BG), cellobiohydrolase (CBH), xylosidase (XYL), phenol oxidase (POX), peroxidase (PER) and N-acetyl glucosamide (NAG). Enzyme activity rates were normalized by soil weight, soil organic C (SOC), and microbial biomass C (MBC). Specific enzyme activity (per SOC or MBC) was more sensitive to drainage and soil depth compared to normalization by soil weight. In Oi and Oa horizons, specific enzyme activity (per MBC) (AG, BG, XYL, POX, PER) was higher in the natural compared to drained wetland but lower (AG, CBH, XYL, POX, PER, NAG) in the AB or B mineral soils. Results from this study indicate that organic soil horizons of natural freshwater wetlands contain a highly active microbial community driven by inputs of plant-derived C, while deeper soils of the drained wetland exhibit higher microbial metabolic activity, which likely plays a role in SOC storage of these systems.}, number={6}, journal={Forests}, publisher={MDPI AG}, author={Minick, Kevan J. and Aguilos, Maricar and Li, Xuefeng and Mitra, Bhaskar and Prajapati, Prajaya and King, John S.}, year={2022}, month={May}, pages={861} }
 @article{morkoc_aguilos_noormets_minick_ile_dickey_hardesty_kerrigan_heitman_king_2022, title={Environmental and Plant-Derived Controls on the Seasonality and Partitioning of Soil Respiration in an American Sycamore (Platanus occidentalis) Bioenergy Plantation Grown at Different Planting Densities}, volume={13}, ISSN={1999-4907}, url={http://dx.doi.org/10.3390/f13081286}, DOI={10.3390/f13081286}, abstractNote={Bioenergy is one of the most considered alternatives to fossil fuels. Short-rotation woody crops (SRWCs) as bioenergy sources are capable of alleviating energy constraints and sequestering atmospheric CO2. However, studies investigating soil carbon (C) dynamics at SWRC plantations are scarce. We studied American sycamore (Platanus occidentalis) as a model tree species for SRWC at different planting densities ((1) 0.5 × 2.0 m (10,000 trees·ha−1 or tph), (2) 1.0 × 2.0 m (5000 tph), and (3) 2.0 × 2.0 m (2500 tph)) to examine seasonal variation in total soil respiration (Rtotal), partitioned into heterotrophic (Rh) and autotrophic (Ra) respiration, and we evaluated climatic and biological controls on soil respiration. Rtotal and Rh exhibited larger seasonal variation than Ra (p < 0.05). During the nongrowing seasons, the average Rtotal was 0.60 ± 0.21 g·C·m−2·day−1 in winter and 1.41 ± 0.73 g·C·m−2·day−1 in fall. During the growing season, Rtotal was 2–7 times higher in spring (3.49 ± 1.44 g·C·m−2·day−1) and summer (4.01 ± 1.17 g·C·m−2·day−1) than winter. Average Rtotal was 2.30 ± 0.63 g·C·m−2·day−1 in 2500 tph, 2.43 ± 0.64 g·C·m−2·day−1 in 5000 tph, and 2.41 ± 0.75 g·C·m−2·day−1 in 10,000 tph treatments. Average Rh was 1.72 ± 0.40 g·C·m−2·day−1 in 2500 tph, 1.57 ± 0.39 g·C·m−2·day−1 in 5000 tph, and 1.93 ± 0.64 g·C·m−2·day−1 in 10,000 tph, whereas Ra had the lowest rates, with 0.59 ± 0.53 g·C·m−2·day−1 in 2500 tph, 0.86 ± 0.51 g·C·m−2·d−1 in 5000 tph, and 0.48 ± 0.34 g·C·m−2·day−1 in 10,000 tph treatments. Rh had a greater contribution to Rtotal (63%–80%) compared to Ra (20%–37%). Soil temperature was highly correlated to Rtotal (R2 = 0.92) and Rh (R2 = 0.77), while the correlation to Ra was weak (R2 = 0.21). Rtotal, Rh, and Ra significantly declined with soil water content extremes (e.g., <20% or >50%). Total root biomass in winter (469 ± 127 g·C·m−2) was smaller than in summer (616 ± 161 g·C·m−2), and the relationship of total root biomass to Rtotal, Rh, and Ra was only significant during the growing seasons (R2 = 0.12 to 0.50). The litterfall in 5000 tph (121 ± 16 g DW·m−2) did not differ (p > 0.05) from the 2500 tph (108 ± 16 g DW·m−2) or 10,000 tph (132 ± 16 g DW·m−2) treatments. In no circumstances were Rtotal, Rh, and Ra significantly correlated with litterfall amount across planting densities and seasons (p > 0.05). Overall, our results show that Rtotal in American sycamore SRWC is dominated by the heterotrophic component (Rh), is strongly correlated to soil environmental conditions, and can be minimized by planting at a certain tree density (5000 tph).}, number={8}, journal={Forests}, publisher={MDPI AG}, author={Morkoc, Suna and Aguilos, Maricar and Noormets, Asko and Minick, Kevan J. and Ile, Omoyemeh and Dickey, David A. and Hardesty, Deanna and Kerrigan, Maccoy and Heitman, Joshua and King, John}, year={2022}, month={Aug}, pages={1286} }
 @article{aguilos_warr_irving_gregg_grady_peele_noormets_sun_liu_mcnulty_et al._2022, title={The Unabated Atmospheric Carbon Losses in a Drowning Wetland Forest of North Carolina: A Point of No Return?}, volume={13}, ISSN={1999-4907}, url={http://dx.doi.org/10.3390/f13081264}, DOI={10.3390/f13081264}, abstractNote={Coastal wetlands provide the unique biogeochemical functions of storing a large fraction of the terrestrial carbon (C) pool and being among the most productive ecosystems in the world. However, coastal wetlands face numerous natural and anthropogenic disturbances that threaten their ecological integrity and C storage potential. To monitor the C balance of a coastal forested wetland, we established an eddy covariance flux tower in a natural undrained bottomland hardwood forest in eastern North Carolina, USA. We examined the long-term trends (2009–2019) in gross primary productivity (GPP), ecosystem respiration (RE), and the net ecosystem C exchange (NEE) seasonally and inter-annually. We analyzed the response of C fluxes and balance to climatic and hydrologic forcings and examined the possible effects of rising sea levels on the inland groundwater dynamics. Our results show that in 2009, a higher annual GPP (1922 g C m−2 yr−1) was observed than annual RE (1554 g C m−2 yr−1), resulting in a net C sink (NEE = −368 g C m−2 yr−1). However, the annual C balance switched to a net C source in 2010 and onwards, varying from 87 g C m−2 yr−1 to 759 g C m−2 yr−1. The multiple effects of air temperature (Tair), net radiation (Rn), groundwater table (GWT) depth, and precipitation (p) explained 66%, 71%, and 29% of the variation in GPP, RE, and NEE, respectively (p < 0.0001). The lowering of GWT (−0.01 cm to −14.26 cm) enhanced GPP and RE by 35% and 28%, respectively. We also observed a significant positive correlation between mean sea level and GWT (R2 = 0.11), but not between GWT and p (R2 = 0.02). Cumulative fluxes from 2009 to 2019 showed continuing C losses owing to a higher rate of increase of RE than GPP. This study contributes to carbon balance accounting to improve ecosystem models, relating C dynamics to temporal trends in under-represented coastal forested wetlands.}, number={8}, journal={Forests}, publisher={MDPI AG}, author={Aguilos, Maricar and Warr, Ian and Irving, Madison and Gregg, Olivia and Grady, Stanton and Peele, Toby and Noormets, Asko and Sun, Ge and Liu, Ning and McNulty, Steve and et al.}, year={2022}, month={Aug}, pages={1264} }
 @article{minick_leggett_sucre_fox_strahm_2021, title={Bioenergy production effects on SOM with depth of loblolly pine forests on Paleaquults in southeastern USA}, volume={27}, ISSN={["2352-0094"]}, DOI={10.1016/j.geodrs.2021.e00428}, abstractNote={Managed loblolly pine (P. taeda L.) forests comprise a major land-use across the “wood basket” of the southeastern US. Lower coastal plain loblolly pine forests can enhance carbon (C) storage in fast-growing vegetation and soils, representing a significant opportunity to manage these forests for improved soil health through an understanding of soil C and nitrogen (N) storage. Furthermore, these forests have unrealized potential to produce biomass for emerging bioenergy markets. Despite this, very little is known about how intensified management (herbaceous bioenergy production) of these forests influences short-term soil organic C (SOC) and soil organic N (SON) pools in surface and subsurface soil horizons. The field site was located in the Lower Coastal Plain of North Carolina, USA in which trees were planted in bedded (e.g., raised) rows (bed) and intercropped with or without switchgrass (P. virgatum L.) between the bedded rows of trees (interbed). Soils were collected from four depths (0–5, 5–15, 15–30, and 30–45 cm) and two locations (bed and interbed regions) and fractionated into light and heavy mineral-associated SOC and SON pools using a sequential density fractionation technique. Bulk soil SOC and SON concentration as well as C:N ratio decreased with depth for both treatments, while 15N became enriched. Free and occluded lighter fractions (< 1.65 g cm−3) had higher SOC and SON concentration (~45% C and ~ 1.15% N) compared to medium (1.65–2.00 g cm−3) and heavy (> 2.00 g cm−3) fractions. At the 0–5 cm depth in interbeds, SOC and SON were concentrated in the free light fraction (~45%), but transitioned to being concentrated in the heaviest mineral-associated fraction at the 15–30 (~55%) and 30–45 (~70%) cm depth. The 15N analysis of density fractions indicated progressive enrichment with increasing density, suggesting increasing incorporation of microbially-derived products into stable mineral-associated soil organic matter (SOM) pools. In the pine-switchgrass treatment, SOC and SON concentrations were higher in the light and medium fractions in beds and interbeds compared to the pine only treatment, particularly at the 30–45 cm depth. The C:N ratio in the pine-switchgrass treatment was higher compared to the pine only treatment indicating inputs of new plant-derived organic matter. Furthermore, the δ13C stable isotope signature was enriched in both the occluded light fraction (1.65 g cm−3) and the mineral-associated fraction (1.65–1.85 g cm−3). Our results suggest that switchgrass intercropping is contributing to the early buildup of SOM in particulate and mineral-associated SOM pools possibly through additions of new root-derived organic matter and the positive effect on soil microbial activity through priming of microbes.}, journal={GEODERMA REGIONAL}, author={Minick, Kevan J. and Leggett, Zakiya H. and Sucre, Eric B. and Fox, Thomas R. and Strahm, Brian D.}, year={2021}, month={Dec} }
 @article{aguilos_sun_noormets_domec_mcnulty_gavazzi_prajapati_minick_mitra_king_2021, title={Ecosystem Productivity and Evapotranspiration Are Tightly Coupled in Loblolly Pine (Pinus taeda L.) Plantations along the Coastal Plain of the Southeastern U.S.}, volume={12}, ISSN={1999-4907}, url={http://dx.doi.org/10.3390/f12081123}, DOI={10.3390/f12081123}, abstractNote={Forest water use efficiency (WUE), the ratio of gross primary productivity (GPP) to evapotranspiration (ET), is an important variable to understand the coupling between water and carbon cycles, and to assess resource use, ecosystem resilience, and commodity production. Here, we determined WUE for managed loblolly pine plantations over the course of a rotation on the coastal plain of North Carolina in the eastern U.S. We found that the forest annual GPP, ET, and WUE increased until age ten, which stabilized thereafter. WUE varied annually (2–44%), being higher at young plantation (YP, 3.12 ± 1.20 g C kg−1 H2O d−1) compared to a mature plantation (MP, 2.92 ± 0.45 g C kg−1 H2O d−1), with no distinct seasonal patterns. Stand age was strongly correlated with ET (R2 = 0.71) and GPP (R2 = 0.64). ET and GPP were tightly coupled (R2 = 0.86). Radiation and air temperature significantly affected GPP and ET (R2 = 0.71 − R2 = 0.82) at a monthly scale, but not WUE. Drought affected WUE (R2 = 0.35) more than ET (R2 = 0.25) or GPP (R2 = 0.07). A drought enhanced GPP in MP (19%) and YP (11%), but reduced ET 7% and 19% in MP and YP, respectively, resulting in a higher WUE (27–32%). Minor seasonal and interannual variation in forest WUE of MP (age > 10) suggested that forest functioning became stable as stands matured. We conclude that carbon and water cycles in loblolly pine plantations are tightly coupled, with different characteristics in different ages and hydrologic regimes. A stable WUE suggests that the pine ecosystem productivity can be readily predicted from ET and vice versa. The tradeoffs between water and carbon cycling should be recognized in forest management to achieve multiple ecosystem services (i.e., water supply and carbon sequestration).}, number={8}, journal={Forests}, publisher={MDPI AG}, author={Aguilos, Maricar and Sun, Ge and Noormets, Asko and Domec, Jean-Christophe and McNulty, Steven and Gavazzi, Michael and Prajapati, Prajaya and Minick, Kevan J. and Mitra, Bhaskar and King, John}, year={2021}, month={Aug}, pages={1123} }
 @article{aguilos_sun_noormets_domec_mcnulty_gavazzi_minick_mitra_prajapati_yang_et al._2021, title={Effects of land-use change and drought on decadal evapotranspiration and water balance of natural and managed forested wetlands along the southeastern US lower coastal plain}, volume={303}, ISSN={["1873-2240"]}, url={https://doi.org/10.1016/j.agrformet.2021.108381}, DOI={10.1016/j.agrformet.2021.108381}, abstractNote={Forested wetlands are important in regulating regional hydrology and climate. However, long-term studies on the hydrologic impacts of converting natural forested wetlands to pine plantations are rare for the southern US. From 2005-2018, we quantified water cycling in two post-harvest and newly-planted loblolly pine (Pinus taeda) plantations (YP2–7, 2–7 yrs old; YP2–8, 2–8 yrs old), a rotation-age loblolly pine plantation (MP, 15–28 yrs old), and a natural bottomland hardwood forest (BHF, > 100 yrs old) along the lower coastal plain of North Carolina. We quantified the differences in inter-annual and seasonal water balance and trends of evapotranspiration (ET) using eddy covariance over 37 site-years and assessed key climatic and biological drivers of ET. We found that the rotation-age plantation (MP) had higher annual ET (933 ± 63 mm) than the younger plantations (776 ± 74 mm for YP2–7 and 638 ± 190 mm for YP2–8), and the BHF (743 ± 172 mm), owing to differences in stand age, canopy cover, and micrometeorology. Chronosequence analysis of the pine sites showed that ET increased with stand age up to 10 years, then gradually stabilized for the remainder of the rotation of 28 – 30 years. YP2–8 was sensitive to water availability, decreasing ET by 30 – 43 % during the extreme 2007 – 2008 drought, but reductions in ET at MP were only 8 – 11 %. Comparing to BHF, ditching with management enhanced drainage at YP2–7 and YP2–8, while drainage was lower at the mature pine site. This study provides insight into land use-hydrology-climate interactions that have important implications for forested wetland management in a time of rapidly changing environmental conditions of the LCP of the southern US.}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={Aguilos, Maricar and Sun, Ge and Noormets, Asko and Domec, Jean-Christophe and McNulty, Steve and Gavazzi, Michael and Minick, Kevan and Mitra, Bhaskar and Prajapati, Prajaya and Yang, Yun and et al.}, year={2021}, month={Jun} }
 @article{aguilos_brown_minick_fischer_ile_hardesty_kerrigan_noormets_king_2021, title={Millennial-Scale Carbon Storage in Natural Pine Forests of the North Carolina Lower Coastal Plain: Effects of Artificial Drainage in a Time of Rapid Sea Level Rise}, volume={10}, ISSN={2073-445X}, url={http://dx.doi.org/10.3390/land10121294}, DOI={10.3390/land10121294}, abstractNote={Coastal forested wetlands provide important ecosystem services along the southeastern region of the United States, but are threatened by anthropogenic and natural disturbances. Here, we examined the species composition, mortality, aboveground biomass, and carbon content of vegetation and soils in natural pine forests of the lower coastal plain in eastern North Carolina, USA. We compared a forest clearly in decline (termed “ghost forest”) adjacent to a roadside canal that had been installed as drainage for a road next to an adjacent forest subject to “natural” hydrology, unaltered by human modification (termed “healthy forest”). We also assessed how soil organic carbon (SOC) accumulation changed over time using 14C radiocarbon dating of wood sampled at different depths within the peat profile. Our results showed that the ghost forest had a higher tree density at 687 trees ha−1, and was dominated by swamp bays (Persea palustric), compared to the healthy forest, which had 265 trees ha−1 dominated by pond pine (Pinus serotina Michx). Overstory tree mortality of the ghost forest was nearly ten times greater than the healthy forest (p < 0.05), which actually contributed to higher total aboveground biomass (55.9 ± 12.6 Mg C ha−1 vs. 27.9 ± 8.7 Mg ha−1 in healthy forest), as the dead standing tree biomass (snags) added to that of an encroaching woody shrub layer during ecosystem transition. Therefore, the total aboveground C content of the ghost forest, 33.98 ± 14.8 Mg C ha−1, was higher than the healthy forest, 24.7 ± 5.2 Mg C ha−1 (p < 0.05). The total SOC stock down to a 2.3 m depth in the ghost forest was 824.1 ± 46.2 Mg C ha−1, while that of the healthy forest was 749.0 ± 170.5 Mg C ha−1 (p > 0.05). Carbon dating of organic sediments indicated that, as the sample age approaches modern times (surface layer year 2015), the organic soil accumulation rate (1.11 to 1.13 mm year−1) is unable to keep pace with the estimated rate of recent sea level rise (2.1 to 2.4 mm year−1), suggesting a causative relationship with the ecosystem transition occurring at the site. Increasing hydrologic stress over recent decades appears to have been a major driver of ecosystem transition, that is, ghost forest formation and woody shrub encroachment, as indicated by the far higher overstory tree mortality adjacent to the drainage ditch, which allows the inland propagation of hydrologic/salinity forcing due to SLR and extreme storms. Our study documents C accumulation in a coastal wetland over the past two millennia, which is now threatened due to the recent increase in the rate of SLR exceeding the natural peat accumulation rate, causing an ecosystem transition with unknown consequences for the stored C; however, much of it will eventually be returned to the atmosphere. More studies are needed to determine the causes and consequences of coastal ecosystem transition to inform the modeling of future coastal wetland responses to environmental change and the estimation of regional terrestrial C stocks and flux.}, number={12}, journal={Land}, publisher={MDPI AG}, author={Aguilos, Maricar and Brown, Charlton and Minick, Kevan and Fischer, Milan and Ile, Omoyemeh J. and Hardesty, Deanna and Kerrigan, Maccoy and Noormets, Asko and King, John}, year={2021}, month={Nov}, pages={1294} }
 @article{ile_aguilos_morkoc_minick_domec_king_2021, title={Productivity of low-input short-rotation coppice American sycamore ( Platanus occidentalis L.) grown at different planting densities as a bioenergy feedstock over two rotation cycles}, volume={146}, ISSN={["1873-2909"]}, url={https://doi.org/10.1016/j.biombioe.2021.105983}, DOI={10.1016/j.biombioe.2021.105983}, abstractNote={Short rotation coppice culture of woody crop species (SRWCs) has long been considered a sustainable method of producing biomass for bioenergy that does not compete with current food production practices. In this study, we grew American sycamore (Platanus occidentalis L.) for nine years corresponding to two rotation cycles (first rotation (FR) = 2010–2014, second rotation (SR) = 2015–2019). This was done at varying tree planting densities (1250, 2500, 5000, and 10,000 trees per hectare (tph)) on a degraded agricultural landscape under low-input (e.g. no fertilizer and low herbicide application) culture, in the Piedmont physiographic region of eastern North Carolina. Tree productivity was proportional to planting density, with the highest cumulative aboveground wood biomass in the 10,000 tph treatment, at 23.2 ± 0.9 Mg ha−1 and 39.1 ± 2.4 Mg ha−1 in the first and second rotations, respectively. These results demonstrate increasing productivity under a low-input SRWC management regime over the first two rotations. Biomass partitioning was strongly affected by planting density during FR, allocating less biomass to stems relative to other plant parts at low planting density (44–59% from 1250 to 10,000 tph, respectively). This effect disappeared during SR, however, with biomass partitioning to stems ranging from 74 to 79% across planting densities. Taken together, our results suggest that American sycamore has the potential to be effectively managed as a bioenergy feedstock with low input culture on marginal agriculture lands.}, journal={BIOMASS & BIOENERGY}, author={Ile, Omoyemeh J. and Aguilos, Maricar and Morkoc, Suna and Minick, Kevan and Domec, Jean-Christophe and King, John S.}, year={2021}, month={Mar} }
 @article{minick_mitra_li_fischer_aguilos_prajapati_noormets_king_2021, title={Wetland microtopography alters response of potential net CO2 and CH4 production to temperature and moisture: Evidence from a laboratory experiment}, volume={402}, ISSN={["1872-6259"]}, url={https://doi.org/10.1016/j.geoderma.2021.115367}, DOI={10.1016/j.geoderma.2021.115367}, abstractNote={Coastal wetlands store significant amounts of carbon (C) belowground, which may be altered through effects of rising temperature and changing hydrology on CO2 and CH4 fluxes and related microbial activities. Wetland microtopography (hummock-hollow) also plays a critical role in mediating plant growth, microbial activity, and thus cycling of C and nutrients and may interact with rising seas to influence coastal wetland C dynamics. Recent evidence suggests that CH4 production in oxygenated surface soils of freshwater wetlands may contribute substantially to global CH4 production, but comprehensive studies linking potential CH4 production to environmental and microbial variables in temperate freshwater forested wetlands are lacking. This study investigated effects of temperature, moisture, and microtopography on potential net CO2 and CH4 production and extracellular enzyme activity (β-glucosidase, xylosidase, phenol oxidase, and peroxidase) in peat soils collected from a freshwater forested wetland in coastal North Carolina, USA. Soils were retrieved from three microsites (hummock, hollow, and subsurface peat soils (approximately 20–40 cm below surface)) and incubated at two temperatures (27 °C and 32 °C) and soil water contents (65% and 100% water holding capacity (WHC)). Hummocks had the highest cumulative potential net CO2 (13.7 ± 0.90 mg CO2-C g soil−1) and CH4 (1.8 ± 0.42 mg CH4-C g soil−1) production and enzyme activity, followed by hollows (8.7 ± 0.91 mg CO2-C g soil−1 and 0.5 ± 0.12 mg CH4-C g soil−1) and then subsurface soils (5.7 ± 0.70 mg CO2-C g soil−1 and 0.04 ± 0.019 mg CH4-C g soil−1). Fully saturated soils had lower potential net CO2 production (50–80%) and substantially higher potential net CH4 production compared to non-saturated soils (those incubated at 65% WHC). Soils incubated at 32 °C increased potential net CO2 (24–34%) and CH4 (56–404%) production under both soil moisture levels compared to those incubated at 27 °C. The Q10 values for potential net CO2 and CH4 production ranged from 1.5 to 2.3 and 3.3–8.8, respectively, and did not differ between any microsites or soil water content. Enrichment of δ13CO2-C was found in saturated soils from all microsites (−24.4 to − 29.7 ‰) compared to non-saturated soils (−31.1 to − 32.4 ‰), while δ13CH4-C ranged from −62 to −55‰ in saturated soils. Together, the CO2 and CH4 δ13C data suggest that acetoclastic methanogenesis is an important pathway for CH4 production in these wetlands. A positive relationship (Adj. R2 = 0.40) between peroxidase activity and CH4 production was also found, indicating that peroxidase activity may be important in providing fermented C substrates to acetoclastic methanogenic communities and contribute to anaerobic C mineralization. These results suggest that changes in temperature and hydrology could stimulate CO2 and CH4 emissions from surface hummock soils, and to a lesser extent from hollow soils, and provide preliminary evidence that hummocks may be a spatially important and unrecognized hotspot for CH4 production.}, journal={GEODERMA}, author={Minick, Kevan J. and Mitra, Bhaskar and Li, Xuefeng and Fischer, Milan and Aguilos, Maricar and Prajapati, Prajaya and Noormets, Asko and King, John S.}, year={2021}, month={Nov} }
 @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={Abstract}, 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} }
 @misc{pandey_kumar_kaviraj_minick_mishra_singh_2020, title={DNRA: A short-circuit in biological N-cycling to conserve nitrogen in terrestrial}, volume={738}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2020.139710}, abstractNote={This paper reviews dissimilatory nitrate reduction to ammonium (DNRA) in soils - a newly appreciated pathway of nitrogen (N) cycling in the terrestrial ecosystems. The reduction of NO3- occurs in two steps; in the first step, NO3- is reduced to NO2-; and in the second, unlike denitrification, NO2- is reduced to NH4+ without intermediates. There are two sets of NO3-/NO2- reductase enzymes, i.e., Nap/Nrf and Nar/Nir; the former occurs on the periplasmic-membrane and energy conservation is respiratory via electron-transport-chain, whereas the latter is cytoplasmic and energy conservation is both respiratory and fermentative (Nir, substrate-phosphorylation). Since, Nir catalyzes both assimilatory- and dissimilatory-nitrate reduction, the nrfA gene, which transcribes the NrfA protein, is treated as a molecular-marker of DNRA; and a high nrfA/nosZ (N2O-reductase) ratio favours DNRA. Recently, several crystal structures of NrfA have been presumed to producee N2O as a byproduct of DNRA via the NO (nitric-oxide) pathway. Meta-analyses of about 200 publications have revealed that DNRA is regulated by oxidation state of soils and sediments, carbon (C)/N and NO2-/NO3- ratio, and concentrations of ferrous iron (Fe2+) and sulfide (S2-). Under low-redox conditions, a high C/NO3- ratio selects for DNRA while a low ratio selects for denitrification. When the proportion of both C and NO3- are equal, the NO2-/NO3- ratio modulates partitioning of NO3-, and a high NO2-/NO3- ratio favours DNRA. A high S2-/NO3- ratio also promotes DNRA in coastal-ecosystems and saline sediments. Soil pH, temperature, and fine soil particles are other factors known to influence DNRA. Since, DNRA reduces NO3- to NH4+, it is essential for protecting NO3- from leaching and gaseous (N2O) losses and enriches soils with readily available NH4+-N to primary producers and heterotrophic microorganisms. Therefore, DNRA may be treated as a tool to reduce ground-water NO3- pollution, enhance soil health and improve environmental quality.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Pandey, C. B. and Kumar, Upendra and Kaviraj, Megha and Minick, K. J. and Mishra, A. K. and Singh, J. S.}, year={2020}, month={Oct} }
 @article{li_minick_luff_noormets_miao_mitra_domec_sun_mcnulty_king_2020, title={Effects of Microtopography on Absorptive and Transport Fine Root Biomass, Necromass, Production, Mortality and Decomposition in a Coastal Freshwater Forested Wetland, Southeastern USA}, volume={23}, ISSN={["1435-0629"]}, DOI={10.1007/s10021-019-00470-x}, abstractNote={Forested wetlands are an important carbon (C) sink. Fine roots (diameter < 2 mm) dominate belowground C cycling and can be functionally defined into absorptive roots (order 1–2) and transport roots (order ≥ 3). However, effects of microtopography on the function-based fine root dynamics in forested wetlands are poorly understood. We studied fine root biomass allocation and biomass, necromass, mass loss rate, production, mortality and decomposition of absorptive and transport roots in hummocks and hollows in a coastal plain freshwater forested wetland (FFW) in the southeastern USA using dynamic-flow method. Biomass ratios of first- to second-order roots and absorptive to transport roots and the biomass and necromass of absorptive and transport roots were significantly higher in top 0–10 cm organic peat layer than in 10–20 cm muck and mineral layer, and were significantly higher in hummocks than in hollows. The mass loss rate, production, mortality and decomposition were significantly higher in hummocks than in hollows. Absorptive roots did not have a lower mass loss rate than transport roots. Microtopography significantly affected the contributions of absorptive and transport roots to the total production, mortality and decomposition. Production, mortality and decomposition of absorptive roots were higher than those of transport roots in hummocks but lower than those of transport roots in hollows. Total (hummocks plus hollows) fine root production, mortality and decomposition were 455 ± 106 g m−2 y−1, 475 ± 79 g m−2 y−1 and 392 ± 60 g m−2 y−1, respectively. Greater mortality than decomposition resulted in net fine root C input to soil. The observed microtopographic controls on fine root dynamics have great implications for soil C cycling. As sea level rises, the relative area of hollows in coastal plain FFWs will increase, causing a decrease in fine root mass loss rate, biomass, production, mortality and decomposition and it is the balance of these processes that will determine future soil C storage and cycling.}, number={6}, journal={ECOSYSTEMS}, author={Li, Xuefeng and Minick, Kevan J. and Luff, Jordan and Noormets, Asko and Miao, Guofang and Mitra, Bhaskar and Domec, Jean-Christophe and Sun, Ge and McNulty, Steven and King, John S.}, year={2020}, month={Sep}, pages={1294–1308} }
 @article{aguilos_mitra_noormets_minick_prajapati_gavazzi_sun_mcnulty_li_domec_et al._2020, title={Long-term carbon flux and balance in managed and natural coastal forested wetlands of the Southeastern USA}, volume={288}, ISSN={["1873-2240"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85085132484&partnerID=MN8TOARS}, DOI={10.1016/j.agrformet.2020.108022}, abstractNote={Wetlands store large carbon (C) stocks and play important roles in biogeochemical C cycling. However, the effects of environmental and anthropogenic pressures on C dynamics in lower coastal plain forested wetlands in the southern U.S. are not well understood. We established four eddy flux stations in two post-harvest and newly-planted loblolly pine plantations (YP2–6, 2–6 yrs old; YP2–8, 2–8 yrs old), a rotation-aged loblolly pine plantations (MP, 15–27 yrs old), and a mixed bottomland hardwood forest (BHF, >100 yrs old) in the lower coastal plain of North Carolina, USA. We analyzed the gross primary productivity (GPP), ecosystem respiration (RE) and net ecosystem exchange (NEE) for age-related trends, interannual variability in response to climate forcing, and management-related disturbances from 2005 – 2017. For the first few years after being harvested, pine plantations were net C sources (NEE = 1133 and 897 g C m–2 yr–1 in YP2–6 and YP2–8, respectively). The MP was a strong C sink (–369 to –1131 g C m–2 yr–1) over the entire study period. In contrast, BHF was a C source (NEE = 87 g C m–2 yr–1 to 759 g C m–2 yr–1) in most years, although in the first year it did show a net C uptake (NEE = –368 g C m–2 yr–1). The source activity of BHF may have been related to increasing overstory tree mortality and diameter growth suppression. Decreases in relative extractable water in pine plantations enhanced GPP and RE. Pine plantations regained status as C sinks 5–8 years after harvest and recovered C equivalent to post-harvest losses at 8–14 years. Thus, coastal pine plantations have a net C uptake for only about half the 25-year rotation period, suggesting that they have decreased climate mitigation potential in comparison to protecting primary forests. However, primary forests in this area may be vulnerable to ecosystem transition, and subsequent C loss, due to the changing environmental conditions at the land-ocean interface.}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, publisher={Elsevier BV}, author={Aguilos, Maricar and Mitra, Bhaskar and Noormets, Asko and Minick, Kevan and Prajapati, Prajaya and Gavazzi, Michael and Sun, Ge and McNulty, Steve and Li, Xuefeng and Domec, Jean-Christophe and et al.}, year={2020}, month={Jul} }
 @article{mitra_minick_miao_domec_prajapati_mcnulty_sun_king_noormets_2020, title={Spectral evidence for substrate availability rather than environmental control of methane emissions from a coastal forested wetland}, volume={291}, ISSN={["1873-2240"]}, DOI={10.1016/j.agrformet.2020.108062}, abstractNote={Knowledge of the dynamics of methane (CH4) fluxes across coastal freshwater forested wetlands, such as those found in the southeastern US remains limited. In the current study, we look at the spectral properties of ecosystem net CH4 exchange (NEECH4) time series, and its cospectral behavior with key environmental conditions (temperature (Ts5), water table (WTD) and atmospheric pressure (Pa)) and physiological fluxes (photosynthesis (GPP), transpiration (LE), sap flux (Js)) using data from a natural bottomland hardwood swamp in eastern North Carolina. NEECH4 fluxes were measured over five years (2012 – 2016) that included both wet and dry years. During the growing season, strong cospectral peaks at diurnal scale were detected between CH4 efflux and GPP, LE and Js. This suggests that the well understood diurnal cycles in the latter processes may affect CH4 production through substrate availability (GPP) and transport (sap flow and LE). The causality between different time series was established by the magnitude and consistency of phase shifts. The causal effect of Ts5 and Pa were ruled out because despite cospectral peaks with CH4, their phase relationships were inconsistent. The effect of fluctuations in WTD on CH4 efflux at synoptic scale lacked clear indications of causality, possibly due to time lags and hysteresis. The stronger cospectral peak with ecosystem scale LE rather than Js suggested that the evaporative component of LE contributed equally with plant transpiration. Hence, we conclude that while the emission of dissolved gases through plants likely takes place, it may not contribute to higher CH4 emissions as has been proposed by aerenchymatous gas transport in sedge wetlands. These findings can inform future model development by (i) highlighting the coupling between vegetation processes and CH4 emissions, and (ii) identifying specific and non-overlapping timescales for different driving factors.}, journal={AGRICULTURAL AND FOREST METEOROLOGY}, author={Mitra, Bhaskar and Minick, Kevan and Miao, Guofang and Domec, Jean-Christophe and Prajapati, Prajaya and McNulty, Steve G. and Sun, Ge and King, John S. and Noormets, Asko}, year={2020}, month={Sep} }
 @article{mitra_miao_minick_mcnulty_sun_gavazzi_king_noormets_2019, title={Disentangling the Effects of Temperature, Moisture, and Substrate Availability on Soil CO2 Efflux}, volume={124}, ISSN={["2169-8961"]}, DOI={10.1029/2019JG005148}, abstractNote={Abstract}, number={7}, journal={JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES}, author={Mitra, Bhaskar and Miao, Guofang and Minick, Kevan and McNulty, Steve G. and Sun, Ge and Gavazzi, Michael and King, John S. and Noormets, Asko}, year={2019}, month={Jul}, pages={2060–2075} }
 @article{minick_kelley_miao_li_noormets_mitra_king_2019, title={Microtopography Alters Hydrology, Phenol Oxidase Activity and Nutrient Availability in Organic Soils of a Coastal Freshwater Forested Wetland}, volume={39}, ISSN={["1943-6246"]}, DOI={10.1007/s13157-018-1107-5}, number={2}, journal={WETLANDS}, author={Minick, Kevan J. and Kelley, Alexia M. and Miao, Guofang and Li, Xuefeng and Noormets, Asko and Mitra, Bhaskar and King, John S.}, year={2019}, month={Apr}, pages={263–273} }
 @article{wepking_badgley_barrett_knowlton_lucas_minick_ray_shawver_strickland_2019, title={Prolonged exposure to manure from livestock-administered antibiotics decreases ecosystem carbon-use efficiency and alters nitrogen cycling}, volume={22}, ISSN={["1461-0248"]}, DOI={10.1111/ele.13390}, abstractNote={Abstract}, number={12}, journal={ECOLOGY LETTERS}, author={Wepking, Carl and Badgley, Brian and Barrett, John E. and Knowlton, Katharine F. and Lucas, Jane M. and Minick, Kevan J. and Ray, Partha P. and Shawver, Sarah E. and Strickland, Michael S.}, year={2019}, month={Dec}, pages={2067–2076} }
 @article{minick_mitra_noormets_king_2019, title={Saltwater reduces potential CO2 and CH4 production in peat soils from a coastal freshwater forested wetland}, volume={16}, ISSN={["1726-4189"]}, DOI={10.5194/bg-16-4671-2019}, abstractNote={Abstract. A major concern for coastal freshwater wetland function
and health is the effects of saltwater intrusion on greenhouse gas
production from peat soils. Coastal freshwater forested wetlands are likely
to experience increased hydroperiod with rising sea level, as well as
saltwater intrusion. These potential changes to wetland hydrology may also
alter forested wetland structure and lead to a transition from forest to
shrub/marsh wetland ecosystems. Loss of forested wetlands is already evident
by dying trees and dead standing trees (“ghost” forests) along the
Atlantic coast of the US, which will result in significant alterations to
plant carbon (C) inputs, particularly that of coarse woody debris, to soils.
We investigated the effects of salinity and wood C inputs on soils collected
from a coastal freshwater forested wetland in North Carolina, USA, and
incubated in the laboratory with either freshwater or saltwater (2.5 or 5.0 ppt) and with or without the additions of wood. Saltwater additions at 2.5 and 5.0 ppt reduced CO2 production by 41 % and 37 %, respectively,
compared to freshwater. Methane production was reduced by 98 % (wood-free
incubations) and by 75 %–87 % (wood-amended incubations) in saltwater
treatments compared to the freshwater plus wood treatment. Additions of wood
also resulted in lower CH4 production from the freshwater treatment and
higher CH4 production from saltwater treatments compared to wood-free
incubations. The δ13CH4-C isotopic signature suggested
that, in wood-free incubations, CH4 produced from the freshwater
treatment originated primarily from the acetoclastic pathway, while CH4
produced from the saltwater treatments originated primarily from the
hydrogenotrophic pathway. These results suggest that saltwater intrusion
into coastal freshwater forested wetlands will reduce CH4 production,
but long-term changes in C dynamics will likely depend on how changes in
wetland vegetation and microbial function influence C cycling in peat soils.
                    }, number={23}, journal={BIOGEOSCIENCES}, author={Minick, Kevan J. and Mitra, Bhaskar and Noormets, Asko and King, John S.}, year={2019}, month={Dec}, pages={4671–4686} }
 @article{minick_mitra_li_noormets_king_2019, title={Water Table Drawdown Alters Soil and Microbial Carbon Pool Size and Isotope Composition in Coastal Freshwater Forested Wetlands}, volume={2}, ISSN={["2624-893X"]}, DOI={10.3389/ffgc.2019.00007}, abstractNote={Loss of coastal wetlands is occurring at an increasingly rapid rate due to drainage of these wetlands for alternative land-uses, which also threatens carbon (C) storage in these C-rich ecosystems. Wetland drainage results in water table drawdown and increased peat aeration, which enhances decomposition of previously stabilized peat and changes stable C isotope profiles with soil depth. The effect of water table drawdown on the pool size and δ13C signature of plant C, soil organic C (SOC) and microbial biomass C (MBC) across a range of organic and mineral soils has not previously been reported in coastal freshwater forested wetlands. To this end, litter, roots, and soils were collected from organic and mineral soil horizons in two coastal freshwater forested wetlands in North Carolina with different hydrological regimes: 1) a natural bottomland hardwood forest (natural); and 2) a ditched and drained, intensively-managed wetland for loblolly pine silviculture (managed). We found that hydrology and soil horizon, and to a lesser degree micro-topography, was important in shaping observed differences in size and 13C signature of soil and microbial pools between the natural and managed wetland. The natural wetland had higher SOC and MBC concentrations in the litter, surface organic, and mineral horizons compared to the managed wetland. In the managed wetland, 13C of SOC was enriched across most of the soil profile (Oa and mineral soil horizons) compared to the natural wetland, suggesting enhanced decomposition and incorporation of microbially-derived inputs to soils. Root C concentration decreased with soil depth, while root 13C signature became enriched with soil depth. In the litter and Oe horizon of the natural wetland, MBC was higher and 13C of MBC and SOC was enriched in hummocks compared to hollows. The 13C of MBC and SOC tended to be enriched in upper soil horizons and depleted in lower soil horizons, particularly in the managed wetland. We conclude that drainage of these coastal wetlands has enhanced the breakdown of previously stabilized C and has the potential to alter regional C storage, feedbacks to climate warming, and ecosystem responses to changing environmental conditions.}, journal={FRONTIERS IN FORESTS AND GLOBAL CHANGE}, author={Minick, Kevan J. and Mitra, Bhaskar and Li, Xuefeng and Noormets, Asko and King, John S.}, year={2019}, month={Apr} }
 @article{singh_minick_strickland_wickings_crippen_tarone_benbow_sufrin_tomberlin_pechal_2018, title={Temporal and Spatial Impact of Human Cadaver Decomposition on Soil Bacterial and Arthropod Community Structure and Function}, volume={8}, ISSN={["1664-302X"]}, DOI={10.3389/fmicb.2017.02616}, abstractNote={As vertebrate carrion decomposes, there is a release of nutrient-rich fluids into the underlying soil, which can impact associated biological community structure and function. How these changes alter soil biogeochemical cycles is relatively unknown and may prove useful in the identification of carrion decomposition islands that have long lasting, focal ecological effects. This study investigated the spatial (0, 1, and 5 m) and temporal (3–732 days) dynamics of human cadaver decomposition on soil bacterial and arthropod community structure and microbial function. We observed strong evidence of a predictable response to cadaver decomposition that varies over space for soil bacterial and arthropod community structure, carbon (C) mineralization and microbial substrate utilization patterns. In the presence of a cadaver (i.e., 0 m samples), the relative abundance of Bacteroidetes and Firmicutes was greater, while the relative abundance of Acidobacteria, Chloroflexi, Gemmatimonadetes, and Verrucomicrobia was lower when compared to samples at 1 and 5 m. Micro-arthropods were more abundant (15 to 17-fold) in soils collected at 0 m compared to either 1 or 5 m, but overall, micro-arthropod community composition was unrelated to either bacterial community composition or function. Bacterial community structure and microbial function also exhibited temporal relationships, whereas arthropod community structure did not. Cumulative precipitation was more effective in predicting temporal variations in bacterial abundance and microbial activity than accumulated degree days. In the presence of the cadaver (i.e., 0 m samples), the relative abundance of Actinobacteria increased significantly with cumulative precipitation. Furthermore, soil bacterial communities and C mineralization were sensitive to the introduction of human cadavers as they diverged from baseline levels and did not recover completely in approximately 2 years. These data are valuable for understanding ecosystem function surrounding carrion decomposition islands and can be applicable to environmental bio-monitoring and forensic sciences.}, journal={FRONTIERS IN MICROBIOLOGY}, author={Singh, Baneshwar and Minick, Kevan J. and Strickland, Michael S. and Wickings, Kyle G. and Crippen, Tawni L. and Tarone, Aaron M. and Benbow, M. Eric and Sufrin, Ness and Tomberlin, Jeffery K. and Pechal, Jennifer L.}, year={2018}, month={Jan} }
 @article{minick_fisk_groffman_2017, title={Soil Ca alters processes contributing to C and N retention in the Oa/A horizon of a northern hardwood forest}, volume={132}, ISSN={["1573-515X"]}, DOI={10.1007/s10533-017-0307-z}, number={3}, journal={BIOGEOCHEMISTRY}, author={Minick, Kevan J. and Fisk, Melany C. and Groffman, Peter M.}, year={2017}, month={Feb}, pages={343–357} }
 @article{minick_leggett_sucre_fox_strahm_2017, title={Soil and Aggregate-Associated Carbon in a Young Loblolly Pine Plantation}, volume={182}, ISSN={0038-075X}, url={http://dx.doi.org/10.1097/ss.0000000000000215}, DOI={10.1097/ss.0000000000000215}, abstractNote={ABSTRACT In order to assess the carbon (C) footprint of forest-based bioenergy systems, it is necessary to quantify soil C storage. This study addressed effects of intercropping loblolly pine (Pinus taeda L.) with switchgrass (Panicum virgatum L.) for wood and bioenergy production on soil C storage in coastal North Carolina, USA. Spaces between rows of bedded pine were intercropped with switchgrass or contained native vegetative regrowth after site preparation. Two years after switchgrass establishment, soils were collected from beds and interbeds of each treatment, and C concentration and &dgr;13C were measured in bulk soils and aggregate fractions. Soil C concentration, soil C density (Mg ha−1), and aggregate-associated C were lower in pine beds adjacent to switchgrass compared with pines adjacent to native regrowth. In the greater than 2,000-&mgr;m aggregate size class, 11% of C was derived from new pine inputs in beds of the pine-switchgrass treatment compared to the pine-native treatment. These results indicate that increased belowground C flow in pine beds adjacent to switchgrass may be driving breakdown soil C. In the pine-switchgrass intercropping treatment, a greater percentage of aggregates (by weight and C content) was found in the 2,000- to 250-&mgr;m size class of both beds and interbeds, suggesting that this aggregate size class is sensitive to management. This study provides a baseline analysis of C storage under different management scenarios in pine forests and for investigating long-term (10+ years) impacts. Although presence of switchgrass reduced soil C over the short term, bioenergy intercropping may still be pragmatic from an economical and land-use diversification view point.}, number={7}, journal={Soil Science}, publisher={Ovid Technologies (Wolters Kluwer Health)}, author={Minick, Kevan J. and Leggett, Zakiya H. and Sucre, Eric B. and Fox, Thomas R. and Strahm, Brian D.}, year={2017}, month={Nov}, pages={1} }