John King

A cluster of research sites will be maintained according to the Ameriflux Management Program’s Statement of Work. The sites include a mid-rotation loblolly pine plantation (site code US-NC2 in the Ameriflux and FLUXNET databases, operational since November 2004), and companion sites in young, recently disturbed loblolly pine plantations (US-NC3 starting 2013) and a natural bottomland forested wetland (US-AR/NC4 starting 2009). All sites are located on the lower coastal plain in North Carolina, and represent a historically established land use gradient. With current common management practices and areal coverage of commercial plantations in different edaphic and climatic regions in the SE-US, the two loblolly plantations are representative of a broader area. The core research at the individual sites and across the cluster focuses on the following topic areas: (1) the magnitude, regulation and variability of carbon and water cycles, (2) the tradeoffs of different management objectives, including productivity, carbon sequestration, water yield, biodiversity, and environmental services to surrounding communities, (3) responses to environmental pressures, like drought, pest outbreaks, and air pollution episodes, (4) validation, testing and development of plant gas exchange and ecosystem models of gas exchange and resource use, (5) projecting changes in flux partitioning under changing climate and environmental conditions, and (6) facilitating the development and validation of new measurement and modeling technologies.

The southern US is host to ~130 million hectares of forestland distributed (approximately) as 37 % upland hardwoods, 15 % bottomland hardwoods, 14 % mixed oak-pine, 18 % natural pine and 15 % intensively managed pine. In recent decades, this forest estate has becoming increasingly vulnerable to an array of threats. As the pace of climate change increases and the South becomes increasingly urbanized, the extent to which forest ecosystem services provisioning is compromised remains poorly quantified. Yet through existing networks of forest monitoring programs, process-based ecosystem and landscape models, and remote sensing resources, we have the capacity to develop synthetic understanding of current regional forest conditions across the South. The proposed project will perform a region-wide synthesis of existing data on forest carbon (C) and water cycling using data from the USDA Forest Inventory and Analysis (FIA) program to quantify current forest C storage of the major forest types distributed across the region. We will pair the forest C inventory data with long-term data on forest C and water cycling (GPP, NEP/NEE, NPP, ET, hydrology) from the Ameriflux Program, of which we are long-term members. A subset of research sites that host both inventory plots and eddy-covariance towers will be used to parameterize and validate ecosystem models to faithfully simulate forest C and water cycling of major forest types across the region. Newly developed remote sensing tools, combined with MODIS/Landsat, will then be used to provide detailed distributions of the major forest types across the region, and will be used to directly link RS observations to tower-based fluxes. Finally, we will develop geospatial modeling tools (e.g. GPP = f(forest type, climate, DEM, fire, drought, etc.), tested against tower-model fusion, to scale results and identify the main drivers and threats affecting forest ecosystem services in a spatially-explicit manner across the entire region.

Research supported by NCBRI has shown American sycamore to be especially well-suited to short-rotation woody coppice culture (SRWC) for bioenergy; it is productive with low inputs, resilient to biotic and abiotic stress, establishes well, and can be coppiced indefinitely. The goals of this new phase are to integrate knowledge of sycamore ecophysiology into conventional agricultural systems with the help of local farmers, forge relationships between major bioenergy constituencies in eastern NC, and create extension platforms that reach across the state. To do this, we will: 1) establish new sycamore bioenergy field trials on operational farms in proximity to existing Enviva wood pellet mills; 2) conduct mail surveys of constituencies across the state to gather data on perceived barriers and incentives to adoption of bioenergy cropping; 3) conduct outreach activities, including small group meetings, field tours, mill tours and annual field days to forge relationships and transfer technology, based on field trials and survey results; 4) perform an economic analysis comparing integrated agriculture-sycamore bioenergy SRWC to conventional agriculture (corn/soybeans) to assess market competitiveness; and 5) work with NCDA&CS/Commissioner Troxler/NCBRI to see if the legislature can be persuaded to consider support for (sycamore) bioenergy SRWC in the next NC Farm Bill.

To be widely adopted in North Carolina, a bioenergy cropping system must be compatible with existing farm practices, be productive enough to sustain an industry, and enhance environmental quality. We propose here that integrating short-rotation coppice (SRC) American sycamore for bioenergy into conventional agriculture will achieve all three goals. Our data from Butner, NC, suggests that sycamore can sustain high productivity with low inputs (no fertilizer/herbicides), may improve ag soil properties, and has shown no decrease in stool survival or productivity over two coppicing cycles (9 years). We propose here to test the generality of these results by: 1) continuing the original Butner study through a third rotation (up to12 years old), 2) expanding the study to include new ag fields near Butner and Wallace, NC, to contrast with lower coastal plain sites, 3) to work with ENVIVA to test sycamore biomass wood quality for pellet production and energy yield, 4) get input from local farmers on the potential to integrate sycamore biomass farming to produce purpose-grown feedstock for ENVIVA, and 5) quantify benefits to ag soil properties from sycamore SRC. Data will be available for use in new proposals, economic modeling, and life cycle analysis in cooperation with collaborators.

A cluster of research sites will be maintained according to the Ameriflux Management Program’s Statement of Work. The sites include a mid-rotation loblolly pine plantation (site code US-NC2 in the Ameriflux and FLUXNET databases, operational since November 2004), and companion sites in young, recently disturbed loblolly pine plantations (US-NC3 starting 2013) and a natural bottomland forested wetland (US-AR/NC4 starting 2009). All sites are located on the lower coastal plain in North Carolina, and represent a historically established land use gradient. With current common management practices and areal coverage of commercial plantations in different edaphic and climatic regions in the SE-US, the two loblolly plantations are representative of a broader area. The core research at the individual sites and across the cluster focuses on the following topic areas: (1) the magnitude, regulation and variability of carbon and water cycles, (2) the tradeoffs of different management objectives, including productivity, carbon sequestration, water yield, biodiversity, and environmental services to surrounding communities, (3) responses to environmental pressures, like drought, pest outbreaks, and air pollution episodes, (4) validation, testing and development of plant gas exchange and ecosystem models of gas exchange and resource use, (5) projecting changes in flux partitioning under changing climate and environmental conditions, and (6) facilitating the development and validation of new measurement and modeling technologies.

A cluster of research sites will be maintained according to the Ameriflux Management Program’s Statement of Work. The sites include a mid-rotation loblolly pine plantation (site code US-NC2 in the Ameriflux and FLUXNET databases, operational since November 2004), and companion sites in young, recently disturbed loblolly pine plantations (US-NC3 starting 2013) and a natural bottomland forested wetland (US-AR/NC4 starting 2009). All sites are located on the lower coastal plain in North Carolina, and represent a historically established land use gradient. With current common management practices and areal coverage of commercial plantations in different edaphic and climatic regions in the SE-US, the two loblolly plantations are representative of a broader area. The core research at the individual sites and across the cluster focuses on the following topic areas: (1) the magnitude, regulation and variability of carbon and water cycles, (2) the tradeoffs of different management objectives, including productivity, carbon sequestration, water yield, biodiversity, and environmental services to surrounding communities, (3) responses to environmental pressures, like drought, pest outbreaks, and air pollution episodes, (4) validation, testing and development of plant gas exchange and ecosystem models of gas exchange and resource use, (5) projecting changes in flux partitioning under changing climate and environmental conditions, and (6) facilitating the development and validation of new measurement and modeling technologies.

The world currently loses thousands of hectares of low-lying coastal wetlands every year, attributed mainly to a recent acceleration of sea-level rise (SLR). Loss of coastal wetlands threatens critical services these ecosystems provide. Coastal states and counties need to start planning and implementing adaptation and mitigation strategies now in order to decrease future costs of adjusting to climate change and SLR, and to protect vulnerable stocks of sequestered carbon (C) and limit methane (CH4) emissions. Unfortunately, precise information on how natural and managed coastal ecosystems will change in the coming decades is lacking, and monitoring of such sites is very low. Enhanced observation platforms and predictive models and scaling tools are critically needed. The objectives of the proposed project are threefold: 1) leverage previous Federal investments to sustain eddy covariance flux-tower based long-term ?climate change observatory? experiments in southern forested wetlands; 2) perform a detailed study at the wetlands to determine mechanisms controlling belowground C cycling, particularly the interaction of CO2 and CH4 production with environmental driving variables; and 3) utilize the data to improve parameterization of state-of-the-art ecosystem/hydrologic models specific to forested wetlands and their linkage to larger scale models such as the Community Land Model (CLM). Our working hypothesis is that as the hydrology is forced towards wetter conditions (poorer drainage) due to SLR, emissions of CH4 will increase relative to CO2, increasing the greenhouse forcing of the system. In addition, we expect to see greater dissolved C fluxes. The project will be conducted in collaboration with the USFWS at a natural forested wetland at the Alligator River National Wildlife Refuge in Dare County, NC, and in collaboration with Weyerhaeuser NR Company in industrially managed pine plantations. The proposed project will implement detailed soil C cycling studies that account for variation in micro-topography and fluctuations in water table depth, which our previous work has shown to have strong influence on the partitioning of soil C efflux as CO2 and CH4, and also dissolved forms (dissolved organic carbon ? DOC). We will perform laboratory and field incubations of isotopically labeled wood from the Aspen and Duke FACE Projects to trace the flow of C into soil CO2/CH4 efflux, DOC, and labile and recalcitrant soil organic C (SOC) fractions. The spatially explicit ground-based sampling of C fluxes will be related to ecosystem-level with the eddy covariance tower, and used to parameterize coupled process-based ecosystem-hydrologic models (MIKE SHE-DNDC). Model parameterizations will be validated and linked to regional scale modeling of CLM. The proposed project will elucidate belowground soil C cycling mechanisms that control emission of CO2 and CH4 as affected by global climate change and sea level rise.

This agreement establishes a summer research and mentoring program for undergraduate students to study at NC State University. The project focuses on recruiting students from underserved and underrepresented student-serving institutions. This program directly exposes student participants to cutting edge research surrounding the deployment and monitoring of nine forest ecosystem stress stations (Remote Assessment of Forest Ecosystem Stress (RAFES) project) within the eastern U.S., and in collaboration with USDA Forest Service Research Stations, universities, and other partner research organizations. Under the mentorship of faculty and institutional partners, students will participate in modeling the sensor network of measurements; including: air and soil temperature, precipitation, relative humidity, solar radiation, fuel temperature and moisture, volumetric soil water content and matric potential, and sap flux density. Students will conduct the majority of the analyses in the Tree Physiology and Ecosystem Science Lab, within Department of Forestry and Environmental Resources, and the Center for Geospatial Analytics at North Carolina State University. Further collaboration will occur with cooperators at the USDA Forest Service Eastern Forest Environmental Threat Assessment Center (EFETAC), as well as possible collaborations with researchers at Duke University.

Water availability in terrestrial ecosystems is the most important factor limiting carbon assimilation, plant growth and ecosystem net primary productivity (Boyer 1982, Schulze 1986, Ciais et al. 2005). In addition, water availability influences plant geographic distribution (Allen et al. 2002). The efficiency of water uptake and transport through xylem affects plant growth and survival, helping plants replace water lost during transpiration, prevent desiccation, and allow carbon uptake to continue (Kramer and Boyer 1995). When plant demand exceeds water supply, plants must find other sources of water or make more conservative use of available water to minimize water stress. Since the 1920’s it has been proposed (Weaver 1919), and later experimentally confirmed (Richards and Caldwell 1987), that during times of low transpiration plants can reduce water stress by extracting water from deeper and moister soil layers through plant roots and storing it in the upper, drier soil layers, where it can be utilized when transpirational demand increases. This process, originally called hydraulic lift, and now hydraulic redistribution (hereafter HR) has been shown to widely occur in all vegetated environments. It has been proposed as a mechanism that can buffer plants against water stress during seasonal water deficits and can represent 20-40% of stand water use (Caldwell and Richards 1989, Jackson et al. 2002). The effect of the nighttime pulses of HR is like one of a large capacitor increasing the efficiency of whole-plant water transport and buffering the effects of diurnal and seasonal variations in surface soil water availability on actual canopy evapotranspiration. In addition to affecting energy partitioning (Feddes et al. 2001, Koster et al. 2004, Amenu et al. 2005), the buffered water availability sustains higher canopy conductance (gs) and higher photosynthetic CO2 assimilation, thus having a direct effect on ecosystem carbon balance (Domec et al. 2012). Furthermore, the rewetting of surface soil is likely to sustain higher root and microbial respiration rates, adding yet another mechanism to influencing the net carbon balance. Given the implications and manifestations of HR on different ecosystem processes, and the fact that (i) HR has been observed in most biomes (Neumann & Cardon, 2012), (ii) projected changes in precipitation and VPD are known to have opposite effects on HR (Dawson 2007, Howard et al. 2009), and (iii) limited understanding of the physiological importance of HR and its consequence on climate (e.g., Lee et al. 2005), it is essential that a more mechanistic understanding of the phenomenon be developed. The current study has been established to quantify the contribution of HR to water cycling and drought tolerance of different canopy and root strata in a well characterized forest ecosystem with shallow soils. We will construct a site water and evapotranspiration budget of high temporal resolution, spanning three years, and capturing a range of soil moisture levels. Ultimately, the data will be used to parameterize the soil-plant-atmosphere (SPA) model (Sperry et al., 1992), which in turn will be used to simulate the potential changes in the contribution of HR under increasing temperature, vapor pressure deficit and atmospheric CO2 to both water and carbon exchange of the ecosystem (Domec et al., 2010, 2012). Specifically, we hypothesize that: H1- The responses of water and carbon fluxes to rainfall and water deficits depend on the physical characteristics of the root zone and will not be proportional to the magnitude of precipitation (drought) because nighttime HR will play a critical role in delaying the drying of upper soil layers and in allowing daytime water uptake from the recharged surface soil. H2- Photosynthesis and productivity of understory species and regenerating individuals of overstory species during dry periods will depend on the HR activity of overstory tree roots. H3- Under future climatic scenarios (increase in VPD, night transpiration and higher atmospheric CO2), HR will be re

The Nation's forests provide myriad ecosystem services to society such as supplying wood, fiber and energy, protecting water supplies, abating air pollution, and harboring biodiversity. However, changes in climate, land use, fire regimes and biotic pests threaten the continued existence and ecosystem services provisioning of many forests, with the threats often being regionally specific. Therefore, a geographically distributed forest stress monitoring network is needed to provide decision makers and managers with real-time information needed to adapt short- and long-term forest management activities to changing environmental conditions. To fill this need, the USDA Forest Service Center for Integrated Forest Science and Synthesis recently deployed the Remote Assessment of Forest Stress (RAFES) network, consisting of nine automated forest monitoring stations that continuously monitor forest ecophysiological performance and upload the data via satellite link to an internet-based storage site, where the data will ultimately be quality controlled, summarized, and made available to researchers, managers, policy makers, and the public. In the current project, we will develop computer software algorithms and programming tools to process the large amounts of sapflux (tree transpiration) data being generated by the RAFES network, analyze site-specific and network-wide forest sapflux patterns in response to environmental stress, construct new sapflux probes to maintain the network, and develop data summarization tools to provide graphical summaries of sapflux and forest stress data.