2015 Hubbard Brook Annual Cooperators Meeting : Multiple Element Limitation Study Multiple Element Limitation in Northern Hardwood Ecosystems: The Shoestring Project Jerome Barner, SUNY ESF, jcbarner@syr.edu Mychorrhizal preference change in aspen: AM vs. EM and N vs. P Austin Frewert and Jalina Pannafino, MELNHE, afrewert@syr.edu This study evaluates Ectomycorrhizal colonization in the different treatment plots by counting the number of EM root tips to determine if EM colonization is less pronounced with fertilization. Both Ectomycorrhizae and Arbuscular Mycorrhizae are evaluated on the root tips of Aspen in treatment plots where it is present. Sapflow 2014: Does CaSiO2 enhance water use? Mariann Johnston, SUNY-ESF Ranger School, mjohnston@esf.edu Sapflow 2015: Does N or P also affect water use in the MELNHE plots? Brigid Farrell and Isaac Jo, MELNHE, brigid.farrell@gmail.com Sapflow rates were taken from species of primary canopy dominance over a period of ten days. Optimal rates were used to assess overall productivity in sites of varying nutrient availability. Decomposition in the MELNHE plots: Filter paper and tea bags Matthew Hayden, SUNY- ESF, mlhayden@syr.edu Using a modified version of a new method called the Tea Bag Index, this study addresses two questions- will there be a noticeable difference in decomposition rates of tea across plots? and will the use of tea as litter be sufficient in identifying short term trends in decomposition? Does more P mean less BBD? Beech bark disease in the MELNHE plots Aaliyah Jason, SUNY-ESF, amjason@syr.edu Multiple element limitation: Foliar P resorption depends on N availability Kara Phelps, MELNHE, Estimating carbon in fine and coarse woody debris Jessica Swindon, MELNHE, jgswindon@gmail.com To gain a better understanding of the involvement of woody debris in the nutrient cycles of northeastern hardwood forests, fine and course woody debris stock will be measured. The installation of permanent transects will allow for analyses of woody debris decomposition and monitoring of mortality of trees smaller then 10 cm both which have not been done previously. Seasonal pattern of N mineralization in the MELNHE plots Caitlin Holmes, MELNHE, cvholmes@asu.edu I will compare N mineralization in three mature stands in the Bartlett Experimental Forest over the growing season. We are interested in observing a seasonal variance in N mineralization before and after nutrient manipulations are applied. Does CaSiO2 enhance soil respiration, fine root production, or microbial activity? Tyler Sadutto, MELNHE, tyler.sadutto@student.fus.edu Soil respiration is thought to decrease within increasing nutrient availability regardless of the element. This study examines the response of soil respiration to an addition of wollastonite by using LI-COR 8100. 2015 Hubbard Brook Annual Cooperators Meeting : Heterotrophs Mercury bioaccumulation in the food webs of headwater streams Nicholas Rodenhouse, Wellesley College, nrodenho@wellesley.edu We documented mercury (Hg) bioaccumulation in organisms at multiple trophic levels in forests food webs associated with headwaters streams in the Hubbard Brook and Jeffers Brook watersheds. We quantified spatial variation in total Hg (THg) and methyl mercury (meHg) concentrations and bioaccumulation by spiders, salamanders, and birds as well as the prey of these predators, including litter and foliage dwelling insects and the adult stages of aquatic insects. We also quantified the physical and chemical conditions that can affect Hg bioaccumulation. Last we matched mercury bioaccumulation with trophic position in food web structure by using stable isotopes of 15N and 13C. We found elevated levels of Hg in all headwaters food webs. THg and meHg were best predicted by trophic position rather than elevation or location (watershed, stream or proximity to a stream). As expected, predators (spiders, salamanders, birds) accumulated more THg and meHg than lower tropic levels. We concluded that significant Hg bioaccumulation and biomagnification is likely occurring in all high elevation temperate deciduous forests of the Northeast, not just in areas with highest soil moisture, such as the forest associated with headwater streams. A year in the life of a macroinvertebrate community: an exploratory analysis seasonality and flow on benthic assemblages Donovan King, Plymouth State University, kingsofnh@gmail.com Considerable research has examined the conditions of streams using benthic macroinvertebrates (BMI) as bioindicators, yet few studies have described how BMI communities exist over the course of a season, limiting their effectiveness at fine temporal scales. However, observations at these time scales may grow in importance as climate change disrupts seasonal discharge patterns. The aim of my research was to describe stream communities as a function of flow over the course of a season. This study observed two distinct BMI assemblages in the Hubbard Brook Experimental Forest from stream thaw to freeze and explored their relationships to watershed data collected by HBEF staff. The data suggest that fine scale flow variation may be an important driver of community membership and functionality. Long, lean, swimming machines: Morphological correlates of swimming performance in a stream salamander Brett Addis, University of Montana, brett.addis@umontana.edu Defined as permanent movement away from an origin, dispersal in most taxa is characterized by many individuals that stay close to the origin and significantly fewer individuals that leave. Despite the wide-ranging effects dispersal can have on population and evolutionary dynamics, we still do not have a clear understanding of how individual variation in dispersal distance is maintained in natural populations. My research tests for a role of natural selection in maintaining variation in dispersal distance in the stream salamander Gyrinophilus porphyriticus. Here, I assess the relationship between morphological traits and swimming performance, since swimming performance should be directly relevant to dispersal ability. The differential ability of salamander to move through the aquatic environment may represent a proximate mechanism driving variation in dispersal distance in this system. Salamander Community Composition Alters Stream Benthic Macroinvertebrate Densities Claire Bayer, University of Montana, bayercso@gmail.com Intraguild predation occurs when predators with a shared prey item also consume one another. At Hubbard Brook, stream salamanders are intraguild predators. This may affect mortality risk for the benthic macroinvertebrates they consume. To determine if intraguild predation between stream salamanders at Hubbard Brook alters prey risk, I created artificial stream pools with different salamander community compositions. I found that Gyrinophilus porphyriticus reduced benthic macroinvertebrate abundance when its intraguild prey, ,em>Eurycea bislineata, was absent. When both G. porphyriticus and E. bislineata co-occurred, G. porphyriticus did not alter benthic macroinvertebrate densities but did create a trend towards decreased E. bislineata survival. G. porphyriticus seems to be switching from benthic macroinvertebrates to E. bislineata when this prey item is available. The result is lower mortality risk for benthic macroinvertebrates when both salamander species are present than when G. porphyriticus occurs in isolation. E. bislineata did not alter benthic macroinvertebrate densities. Changes in mortality risk for benthic macroinvertebrates with changing salamander community composition may have implications for both in stream processes and insect emergence. Above and below ground abundance and distribution of animals at HB Lynn Christenson, Vassar College, lychristenson@vassar.edu Using the Pradel Andrea Townsend, Hamilton College, aktownse@hamilton.edu Although long-distance migratory songbirds are widely believed to be at risk from warming temperature trends, species capable of attempting more than one brood in a breeding season could benefit from extended breeding seasons in warmer springs. To evaluate local and global factors affecting population dynamics of the black-throated blue warbler (Setophaga caerulescens), a double-brooded long-distance migrant, we used Pradel models to analyze 25 years of mark-recapture data collected in New Hampshire, USA. We assessed the effects of spring temperature (local weather) and the El Niño Southern Oscillation index (a global climate cycle), as well as predator abundance, insect biomass, and local conspecific density on population growth in the subsequent year. Local and global climatic conditions affected warbler populations in different ways. We found that warbler population growth was lower following El Niño years (which have been linked to poor survival in the wintering grounds and low fledging weights in the breeding grounds) than La Niña years. At a local scale, populations increased following years with warm springs and abundant late-season food, but were unaffected by spring temperature following years when food was scarce. These results indicate that the warming temperatures trends might have a positive effect on recruitment and population growth of black-throated blue warblers if food abundance is sustained in breeding areas. In contrast, potential intensification of future El Niño events could negatively impact vital rates and populations of this species. Does perceived predation risk alter maternal contributions to eggs? Nicole Krauss, Washington State University, kraussne@gmail.com Maternal exposure to predation risk may induce changes in her behavior and physiology that can result in changes to offspring phenotype. These phenotypic changes can affect development and last into adulthood. Maternal steroids are one possible mechanism that can produce phenotypic changes to offspring. In oviparous species, egg yolks contain high concentrations of maternal hormones when they are laid that affect the development of the embryo. We exposed laying black-throated blue warbler (Setophaga caerulescens) females to vocalizations of common predators and collected half of their clutch on the day the last egg was laid. These eggs were compared to eggs laid by females exposed to spring peeper (Pseudocris crucifer) vocalizations and eggs of females that did not receive a treatment. Egg mass, yolk mass, clutch size, and five hormones (androstenedione, testosterone, dihydrotestosterone, estradiol, and costicorsterone) were compared among treatment groups. We then continued to monitor the siblings remaining in clutch-reduced nests. Length of the incubation and nestling phases, growth rate, and morphometrics of nestlings remaining in nests were compared among treatment groups. Yolk concentrations of T and A4 were higher in eggs laid by females exposed to the predator treatment than eggs from females in the control group. Only one control nest survived to the late nestling phase, thus data are not currently available to interpret downstream affects. We interpret the increase in A4 and T to be a potentially adaptive response. Androgens are associated with an increase in growth rate, which may aid in predator escape. We are currently repeating this experiment in the 2015 breeding season. Miniaturized GPS Tags Identify Non-breeding Territories of a Small Breeding Migratory Songbird Michael Hallworth, Smithsonian Migratory Bird Center, mhallworth@gmail.com For the first time, we use a small archival global positioning system (GPS) tag to identify and characterize non-breeding territories, quantify migratory connectivity, and identify population boundaries of Ovenbirds (Seiurus aurocapilla), a small migratory songbird, captured at two widely separated breeding locations. We recovered 15 (31%) GPS tags with data and located the non- breeding territories of breeding Ovenbirds from Maryland and New Hampshire, USA (0.50 ± 0.15 ha, mean ± SE). All non-breeding territories had similar environmental attributes despite being distributed across parts of Florida, Cuba and Hispaniola. New Hampshire and Maryland breeding populations had non-overlapping non-breeding population boundaries that encompassed 114,803 and 169,233 km2, respectively. Archival GPS tags provided unprecedented pinpoint locations and associated environmental information of tropical nonbreeding territories. This technology is an important step forward in understanding seasonal interactions and ultimately population dynamics of populations throughout the annual cycle. 2015 Hubbard Brook Annual Cooperators Meeting : Miscellaneous The non-steady state of vegetation dynamics in the Hubbard Brook Valley John Battles, UC Berkeley, jbattles@berkeley.edu The composition of the Northern Forest is in a state of accelerated flux. Evidence from the last decade of forest composition and tree population studies at Hubbard Brook indicate three ongoing shifts in the diversity and dominance of the tree community. The most striking result is the establishment and spread of two climate migrants: northern red oak (Quercus rubra L.) and eastern white pine (Pinus strobus L). Both species are clearly established in the mouth of the Valley, the oldest individuals in our sentry plots are 16 years old, and the populations are spreading uphill along dispersal corridors (i.e., trails and streams). For the vast northern hardwood forest in the Valley, American beech (Fagus grandifolia Ehrh.) is increasing in abundance in the subcanopy stratum of the forest relative to both sugar maple (Acer saccharum Marsh) and yellow birch (Betula alleghaniensis Britton). This transition to beech dominance is the simple maturation of the cohort of disease-induced beech sprouts (what Tom Siccama called beech hell). The implication is that the future canopy composition of the northern hardwood forest will contain a far greater percentage of beech. At the higher elevations, the demise of paper birch (Betula papyrifera Marshall var. cordifolia (Regel) Fernald) is nearly complete -- it is becoming an increasing rare species with high mortality and virtually no recruitment. At the same time, we have documented the unanticipated recovery of red spruce (Picea rubens Sarg.). It is the fastest growing tree species in the Valley and suppression of fir (Abies balsamea (L.) Mill.) saplings by moose herbivory has ensured the establishment of robust understory cohort of spruce. The drivers of these shifts, include what Likens and Franklin (2009) describe as insidious, silent, threats (e.g., climate warming, air pollution, and invasive pests and pathogens) as well the expression of typical community processes (e.g., herbivory, competition, life history). Seeking the Wolf Tree: Hubbard Brook in the schoolyard Natalie Cleavitt, Cornell University, nlc4@cornell.edu The Hubbard Brook book Seeking the Wolf Tree will finally be published in October this year. I will cover topics included in the book and outline our plans for three years of outreach to support use of the book as an educational tool. I will also let you know how and when you can get your own copies! Forest Science Dialogues: Building a model of public engagement with science at a Long Term Ecological Research site Sarah Garlick, Hubbard Brook Research Foundation, sarahgarlick@gmail.com Forest Science Dialogues is a two-year pilot project to develop and test mechanisms of public engagement with science (PES) at a Long Term Ecological Research site. We report findings from the midpoint of the project, including evaluation results from two Hubbard Brook Roundtable dialogues and a needs assessment process to identify priority stakeholder concerns related to the forest ecosystem. Assessing local values and engaging scholarship in the Hubbard Brook Valley & Pemigewasset Watershed Shannon Rogers, Plymouth State University, shrogers@plymouth.edu The push to integrate the social sciences with ecological studies continues to be strong (Redman et al., 2004; Haberl et al., 2009; Collins et al., 2010). In October 2014 Hubbard Brook Research Foundation organized and facilitated a Forest Roundtable: Forging a New Model of Public Engagement with Science as part of its Forest Science Dialogues project. The group convened for the roundtable made a decision that social science should be embedded in the foundation of the Forest Science Dialogues project design. Working with project leaders, we agreed to aggregate existing social science resources to inform the project. The first logical step was a review of data on what people care about in the Hubbard Brook Valley, Pemigewasset Watershed, and more broadly, the Northern Forest. Students in a graduate environmental ethics class at Plymouth State University completed a systematic review of existing data to identify broad themes, which we will share. Future research suggestions and next steps will be shared as well. Co-authors: Graduate Students of ESP 5750 Environmental Ethics - Chelsea Berg, Carly Ellis, Cory Gucwa, Kristen Melendez, Curtis Mooney, Jonathon Loos, Sophia Scott; Sarah Garlick, Director of Science Policy and Outreach Hubbard Brook Research Foundation Solar photovoltaics at Pleasant View Geoff Wilson, HBRF, gwilson@hbresearchfoundation.org HBRF is planning a 41 kilowatt solar array at Pleasant View Farm. It is sized large enough to cover the electricity usage at both Pleasant View and the Mirror Lake Hamlets. The project is being financed by an outside investor and we will have the opportunity to buy the system outright in year 6, at substantially less than the installation costs. Flux Instrumentation at the Hubbard Brook Experimental Forest Daniel Evans, Plymouth State University, dmevans1@plymouth.edu 2015 Hubbard Brook Annual Cooperators Meeting : Ice, Drought, and Water The Ice Storm Experiment (ISE): Understanding Impacts of Ice Storms on Northern Forest Ecosystems Lindsey Rustad, USFS, lrustad@fs.fed.us Ice storms are powerful winter weather events common to temperate and boreal forest regions worldwide. These storms can have catastrophic short-term ecological and socio-economic impacts on forest ecosystems due to branch breakage and toppling of trees under heavy ice loads. They can also have longer-lasting legacies on forest productivity, species composition, the virulence of forest pests and pathogens, and increased risk of fire due to greater fire fuel loads. Here, we present the plan for a new multi-investigator, multi-faceted program of research that includes a novel ice storm manipulation experiment, resampling tree health and vigor at 36 sites in NH and VT established after the 1998 ice storm, and ecosystem and climate modeling. An invitation for additional research within the program will be issued. A Field Plot Study to Evaluate the Effects of a Simulated Ice Storm on a Northern Hardwood Forest at Hubbard Brook Geoff Schwaner, Syracuse University, gwj4@wildcats.unh.edu The Hubbard Brook Ice Storm Experiment (ISE) is a plot-scale experiment being initiated at the HBEF to investigate the impacts of ice storms, or glaze ice events, on northern hardwood forest ecosystems. Building on past ice storm studies, and part of a larger, integrated Ice Storm Study, this experiment will evaluate the short-term (2-3 year) ecosystem response to four different intensities and two frequencies of experimental ice events on large 20- x 30-m plots in the Hubbard Brook Valley. Re-sampling of the 1998 Ice Storm Plots Sarah Geromini, Syracuse University, sgeromini@gmail.com To determine the long-term effects of ice storms on forest ecosystems, we are resampling vegetation at plots that were established by the U.S. Forest Service after the 1998 ice storm. This research includes a complete vegetation inventory (i.e., herbs, seedlings, shrubs, saplings, trees) on 54 20x20 m plots located at 12 sites in New Hampshire and Vermont. We will determine how the level of disturbance influences forest succession by evaluating shifts in seedlings, saplings and diameter classes of larger trees. We will also determine potential changes in species richness and composition of vegetation and evaluate whether invasive species have become established in the aftermath of the disturbance. This study will show how forests respond to ice storms over longer time scales (17+ years) than will be captured with the shorter-term ice storm manipulation experiment. Response of Forest Insects and their Natural Enemies to Simulated Ice Storm Damage in Northern Hardwood Forests Wendy Leuenberger, SUNY-ESF, wleuenbe@syr.edu Large-scale disturbances such as ice storms are likely to increase in frequency and intensity as climate changes. While disturbances are a natural component of forest ecosystems, climatically driven alteration may impart fundamental change to ecosystem function. A novel experiment at Hubbard Brook Experimental Forest, NH, will apply simulated ice storms of varying severity and frequency to replicate northern hardwood plots to develop an empirical understanding of their effects on forests. As part of this experiment, I will quantify effects of ice storm treatments on wood-boring beetles and leaf-feeding Lepidoptera (caterpillars), the most important herbivores in temperate forests. Not only do these groups contain many economically important pest species, collectively they perform vital ecosystem services such as nutrient cycling and decomposition. These insects also facilitate competitive interactions among tree species and contribute to stand productivity. Their natural enemies, including invertebrate and vertebrate predators and a large suite of insect parasitoids, help keep their populations in check. As such, understanding dynamics of these groups after ice storms will aid in forest management and conservation. To assess responses to ice storm damage, I will trap adult and larval wood-boring beetles and their invertebrate natural enemies. Through deployment and retrieval of plasticine model caterpillars, I will estimate bird and invertebrate predation from characteristic 'wounds' to the surrogates. Insectivorous bird species will be measured using point counts. At this point, I am presenting baseline data regarding predation rates and avian diversity. After the ice storm, I expect that beetles and their natural enemies will increase in abundance and diversity, while the effects on caterpillars and their avian predators are less easily predicted. Effects of warmer growing season temperatures and a reduced winter snowpack on sap flow and carbon exchange in a northern hardwood forest Pamela Templer, Boston University, ptempler@bu.edu Mean annual air temperatures for the northeastern U.S. are projected to increase 3 to 5 °C by the year 2100, which could have positive effects on northern hardwood forests through increased water and carbon uptake by trees during the growing season. Climate models also project that warmer air temperatures during the winter will be associated with a smaller and less persistent winter snowpack and increased frequency of soil freeze/thaw cycles, which may offset the positive effects of warming by damaging roots. We conducted an experiment (CCASE = Climate Change Across Seasons Experiment) in a northern hardwood forest at Hubbard Brook Experimental Forest to determine the combined effects of winter and growing season climate on growing season sap flow (i.e. water uptake) by red maple trees. We established six plots (11 X 14 m) in a red maple (Acer rubrum) dominated forest. Two plots are warmed 5 degrees Celsius throughout the growing season. Two others are warmed 5 degrees Celsius in the growing season and have snow removed during winter to induce soil freeze/thaw cycles. Two additional plots serve as references for the experiment. This presentation summarizes the combined effects of climate change across seasons on rates of growing season sap flow and carbon exchange by red maple trees at Hubbard Brook. Effects of warmer temperatures and a smaller winter snowpack on nitrogen uptake and retention in a northern hardwood forest Rebecca Sanders-DeMott, Boston University, rsdemott@bu.edu We conducted a field-based experiment at Hubbard Brook Experimental Forest to assess the combined effects of climate change across seasons on ecosystem nitrogen uptake and retention by northern hardwood forest trees. Climate models project an increase in mean annual air temperatures and a reduction in the depth and duration of winter snowpack for the northeastern United States by the year 2100. The combined effects of these changes in climate will likely lead to warmer soils in the growing season, but increased frequency of soil freeze-thaw cycles in winter due to the reduction of a continuous, insulating snowpack. We established six 11 x 14 m plots in a mixed red maple-beech-birch stand in 2012. Two plots experience growing season warming, two experience growing season warming coupled with freeze-thaw cycles in winter, and two plots experience ambient temperature year-round (reference). Freeze-thaw cycles in winter are achieved by manual snow removal to induce soil freezing followed by warming with buried heating cables to trigger thaws. During the growing season, the same buried heating cables are used to warm the soil 5 degrees C above ambient soil temperatures. We measured root nitrogen uptake, foliar nitrogen content, and ecosystem nitrogen retention throughout the growing season. Rates of nitrogen uptake were greater in the reference and warmed plots compared to the plots that experienced soil freeze/thaw cycles in winter, which corresponded to greater root damage (as measured by root electrolyte leakage). Rates of nitrogen leaching were also greater in the plots experiencing freeze/thaw cycles in winter, suggesting that freeze damage to roots impairs the ability of maple trees to take up nitrogen, which in turn leads to greater nitrogen loss from these forests. Tree roots affect nitrification response to declining winter snowpack Patrick Sorensen, Boston University, patsoren@bu.edu Winter climate change is projected to reduce the depth and duration of snow cover at Hubbard Brook in the next century. Snow cover is a key regulator of winter soil temperature and soil microbial activity during both winter and the growing-season. Additionally, past studies at Hubbard Brook show that loss of winter snow cover is likely to adversely affect tree roots, but whether winter climate change will affect root-microbe interactions remains largely unknown. We took advantage of a natural winter climate gradient at Hubbard Brook where high elevation sites experience more snow and less soil freezing compared to low elevation sites during winter. Soil cores were incubated in nylon mesh that either allowed roots to grow into the soil core or nylon mesh that excluded roots, creating a root-free soil environment. Root biomass ingrowth was related positively to winter soil frost depth and duration. Microbial biomass, enzyme activity, and net N mineralization did not differ amongst root exclusion versus ingrowth cores and were not related to winter snow or frost, but rather positively related to soil volumetric water content. In contrast, net nitrification was related positively to winter snow depth and duration across the gradient and related negatively to root biomass, suggesting that plant-microbial competition for nitrogen (N) may be altered in the wake of winter climate change. DroughtNet: rain exclusions begin! Katie Jennings, University of New Hampshire, katie.jennings@unh.edu Northern Forest DroughtNet is a prototype established at HBEF to test, evaluate and, promote rain manipulation experiments in forested ecosystems, as well as encourage the further development of precipitation change studies in complex ecosystems. The DroughtNet plots have one year of pre-treatment data, and rain exclusion began with the completion of the infrastructure at the end of May 2015. The ultimate infrastructure design is a compromise between efficacy, price and artifacts. Ecosystem response is being measured with a suite of tree, soil and biogeochemical variables sensitive to changes in soil moisture. Orographic Impact on Precipitation Amount in Hubbard Brook Experimental Forest Matthew Cann, Plymouth State University, mdcann1@plymouth.edu Recent research performed with precipitation data from the Hubbard Brook Experimental Forest suggests that in high precipitation events (>15 mm) with a southerly low-level wind regime, the precipitation maxima is located near the lowest part of the valley - contrary to theory and observations in most other places. There is approximately a 2-km latitudinal gap in the current ombrometer network between the north- and south-facing precipitation gauges where the precipitation maxima are likely occurring. A total of 12 precipitation gauges were deployed in early June, 5 gauges to cover the 2-km latitudinal gap in data, and 7 gauges located near RG1, RG19 and HQ to draw statistical relationships between new and existing gauges, and angles to canopy and gauge catch. Precipitation for individual storms >15 mm will be recorded for a 3 month period from June through August 2015 to confirm a valley precipitation maxima. These new data will help us develop a conceptual model of the atmospheric processes that produce the precipitation patterns and to advance our understanding of the precipitation processes in high precipitation events that often lead to flooding in the White Mountain National Forest and downstream. Where does the forest end and the stream begin? Investigating the terrestrial-aquatic interface in headwater catchments Scott Bailey, US Forest Service, swbailey@fs.fed.us Streams in headwater catchments are poorly inventoried and infrequently studied, even at HBEF. At WS3 where the USGS topographic map (blueline) shows 300 m of first order stream channel, we found 800 m of perennial first order stream plus 3 km of ephemeral to intermittent channels. Seasonally flowing streams were found to control temporal variation in DOC concentrations at the catchment outlet and to be sites for denitrification. In addition, 8 groundwater seeps were found and are hotspots for delivery of Si and Ca to the stream network. A corridor of distinct near-stream soils with perennial groundwater blurs the distinction between the stream network and adjacent hillslopes. Currently this work is being extended to WS9 and the west branch of Zig Zag Brook. Preliminary stream network maps in these catchments will be presented. Using a hydropedological framework to identify carbon and nitrogen cycling hotspots Linda Pardo, Forest Service, lpardo@fs.fed.us The hydropedologic approach to soil unit classification highlights the central role that water flowpaths play in soil development. Research at HB has suggested that soil, soil solution, and groundwater chemistry vary systematically by HPU. In this study, we evaluated C and N and their isotopes in bulk soils and soils passed through five sieves sizes (from 500 µm to 63 µm), nitrification, and N and O isotopes in nitrate in groundwater and tension lysimeters from five representative HPUs. Our overall objective was to better identify location, timing, and mechanisms for C and N retention and loss in soils. Specifically, we sought to evaluate whether transects from bedrock outcrops to deeper soils immediately downslope (E to Bhs podzols) were areas of significant C and N cycling in the catchment. Heterogeneity of temperature in Hubbard Brook and responses to warming Denise Burchsted, Keene State College, dburchsted@keene.edu This talk presents in-stream temperature data collected at 15-minute intervals for the past year in the headwaters of Hubbard Brook. These data demonstrate the increased heterogeneity created by natural dams. Overall, water temperature is more variable both within and across these impoundments when compared with forested free-flowing reaches. Additional data from other study sites, including distributed temperature sensing (DTS) data, will be presented to further demonstrate the potential of these features to generate unique refugia. Given the anticipated warming of global climate change, understanding this heterogeneity is essential to provide increased options for organisms to respond to changing temperatures. Linking water age and solute dynamics Kevin McGuire, Virginia Tech, kevin.mcguire@vt.edu We combine experimental and modeling results from WS3 to explore the link between stream solute dynamics and water age. Based on the available information about the hydrology of the site, a transport model was developed and used to compute hydrochemical fluxes at the catchment scale. The model was designed to reproduce the deuterium content of streamflow and allowed for the estimate of catchment water storage and dynamic travel time distributions (TTDs). The innovative contribution of this work is the simulation of dissolved silicon and sodium concentration in streamflow, achieved by implementing first-order chemical kinetics based explicitly on dynamic TTD; thus, upscaling local geochemical processes to the catchment scale. Our results highlight the key-role of water stored within the subsoil glacial material in both the short- and long-term solute circulation. The travel time analysis provided an estimate of streamflow age distributions and their evolution in time related to catchment wetness conditions. The use of age information to reproduce a 14-year dataset of silicon and sodium stream concentration shows that, at catchment scales, the dynamics of such geogenic solutes are mostly controlled by the water travel time, seen as contact time between the water and mineral interfaces. Classification of daily discharge at HBEF Mark Green, USFS/Plymouth State U, mbgreen@plymouth.edu Temporal variation of streamwater aluminum at Hubbard Brook and Cone Pond Carly Ellis, Plymouth State University, cjellis@plymouth.edu The free Al ion is an inorganic form of monomeric aluminum (Ali) that interferes with gill tissue structure, impairing respiratory functions of fish. In order to better understand patterns of toxic Al, this study focuses on the dynamics of streamwater Al over varying temporal scales. Long-term, seasonal, and event-based time scales are the three lenses used in this Ali research. Aluminum toxicity to fish has been shown to be pH-dependent, increasing as pH decreases. Long-term records at Cone Pond and Watershed 9 at Hubbard Brook agree with the long-term decrease in anthropogenic acidification since the discovery of acid rain, showing a decrease Ali. However, Watershed 6 shows an increase in Ali over time, contradicting the Cone Pond and Watershed 9 trends. Seasonal trends show increased Ali around the late winter/early spring and again during the fall. Episodic periods of acidification in the northeastern United States are known to occur during snowmelt and times of increased precipitation. Data analyses of time series show a pulse of streamwater Ali during snowmelt, followed by smaller pulses during summer precipitation events, and another large pulse with the first major precipitation event of the fall season. More frequent sampling during these episodes of increased stream flow and closer examination of existing data will improve the accuracy of confirmatory analyses on the relationship between toxic Al and seasonal and event-based hydrologic trends. Seasonal discharge predictions in regards to temporal variations of North Atlantic sea surface temperature and sea level pressure in the northeastern United States Rouzbeh Berton, Syracuse University, rberton@syr.edu Water planners are interested to be able to predict future variations in discharge metrics to determine if the current water resources are capable of fulfilling future demands or adapting to future changes in climate. The recognition of teleconnection patterns between synoptic-scale circulation and basin-scale hydrology would provide an opportunity for predicting annual or seasonal variations in discharge. The variations in the North Atlantic sea surface temperature and sea-level pressure are speculated to be teleconnected to discharge variability in the northeastern US. The variations of sea surface temperature (SST) in the northern part of Atlantic Ocean are defined by the Atlantic Multi-decadal Oscillation (AMO) index while the variations of sea level pressure above the Atlantic are echoed by the North Atlantic Oscillation (NAO) index. Positive phase of AMO is correspondent to annual rainfall decrement over most of the US (1930 and 1950 droughts) especially over the eastern Mississippi basin; the water surplus in the Colorado River Basin comes with the negative phase of AMO. In the Northeast, negative winter NAO and its intra-seasonal variability will increase snowfall and decreasing summer discharge while positive NAO favors more winter rainfall. The objective of this study is to seek any opportunities of discharge prediction in the northeastern US in regards to extreme positive and negative phases of AMO or NAO. In order to test our hypothesis, we chose the Merrimack Watershed. Merrimack is the fourth largest basin in New England, which drains much of NH and northeastern portions of MA and has sufficient long stream gauge records for such study in the northeastern United States. The extreme phases of AMO and NAO have frequently happened in summer and winter, respectively; therefore the information on summer AMO and winter NAO may provide better opportunities for discharge predictions. 2015 Hubbard Brook Annual Cooperators Meeting : Calcium and Watershed 1 Soil acidity and exchangeable cations after wollastonite treatment on W1: 1998-2014. Chris Johnson, Syracuse University, cejohns@syr.edu Nutrient loss from soil and stream water in a wollastonite treated watershed Charles Driscoll, Syracuse University, ctdrisco@syr.edu Fine root response to calcium mitigation of WS1 Tim Fahey, Cornell, tjf5@cornell.edu Fourteen years after the addition of calcium silicate fine root biomass in the northern hardwood forest declined significantly relative to pre-treatment and reference watershed values. The ratio of fine root:leaf biomass also declined. In the high hardwood zone roots also were more shallowly distributed in the treated watershed. Reduced belowground allocation may contribute to higher aboveground production on the treated watershed. Calcium addition and litter decomposition in watershed 1 Gary Lovett, Cary Institute of Ecosystem Studies, lovettg@caryinstitute.org We studied decomposition of foliar litter in watershed 1 after the calcium silicate addition. We found that addition of calcium did not affect short-term decomposition rates, but it did increase the ultimate extent of decomposition, especially for beech litter. These results indicate the recovery from acidification may affect forest floor carbon dynamics Calcium forms in decomposing wood and bark: a 16-year incubation study. Benjamin Hess, Syracuse University, bjhess@syr.edu Wood and bark samples from fresh and decomposing sugar maple, beech and yellow birch trees were analysed to estimate the content of water-soluble Ca, pectin-bound Ca and Ca-oxalate. We hypothesized that the fraction of Ca in oxalate complexes would increase during decomposition, providing a mechanism for retaining Ca in forest ecosystems. Calcium Isotopes in Hubbard Brook Soils Andy Kurtz, Boston University, kurtz@bu.edu Calcium stable isotope ratios in the soil cation exchange complex reflect the balance between Ca uptake by plants and return by decomposition. Ca isotopes in Hubbard Brook soils are generally isotopically light relative to Ca sources (primary minerals and atmospheric inputs), reflecting the role of 'Ntrient uplift',i.e. vegetation sourcing new Ca from the mineral soil in addition to recycling Ca from the shallow exchange complex. In a study of Ca isotope ratios in the soil exchange complex of Watershed 5, we find that soils became isotopically lighter in the years following the 1983 whole-tree harvest. We interpret this trend as indicative of the role of root decomposition in maintaining the soil Ca pool following removal of aboveground biomass. We've recently begun a study of the long-term evolution of Ca isotopes in Watershed 6 soils in the context of acid rain impacts and recovery. Ca isotopes in W6 Oie soils collected in 1970 are generally isotopically light, more so in the upper part of the watershed. We will complement analysis of these early samples with watershed 6 samples collected in the 1980's, 1990's, and 2000's. Long-term effects of Ca supplementation on foliar chemistry and physiology of red spruce and other hardwoods at WS1 in relation to reference watershed of Hubbard Brook Experimental station, NH. Rakesh Minocha, USDA Forest Service, rminocha@fs.fed.us Identifying source areas of high nitrate export in Watershed 1: Results from a synoptic stream survey. Richard Marinos, Duke University, rem31@duke.edu Since 2008, nitrate export in the calcium silicate-enriched watershed has been steadily increasing and is now over an order of magnitude higher than the biogeochemical reference watershed. Here, I share the results from several synoptic stream surveys of nitrate export in the watershed, and I discuss my future plans for targeted soil sampling based on these measurements. NuPert 2.0: calling all potential collaborators Paul Schaberg, USDA Forest Service, pschaberg@fs.fed.us Twenty years ago, the Nutrient Perturbation (NuPert) study was established at Hubbard Brook to assess how changes in soil calcium (Ca) and aluminum (Al) availability associated with acid deposition may influence tree health and productivity. NuPert is a plot-based (45m x 45m) study with four replicates of three treatments: control (Ca depleted by acid deposition), Ca addition (to replenish depleted Ca) and Al addition (to simulate cation alterations from further acidification). Over the years many improvements in health and productivity have been noted for sugar maple on Ca addition plots including increased growth after canopy release associated with the 1998 ice storm, improved wound closure, increased flowering and seed production, and increased leaf re-flush after spring foliar frost injury. Recently, increased growth was found for American beech on Al addition plots - likely the result of beech release as sensitive sugar maple and yellow birch trees died. This year we are re-treating NuPert plots with Ca and Al to see how continued cation perturbation effects tree structure and function. We are seeking collaborators to assess other aspects of forest system function at NuPert to help provide a more integrated understanding of the legacy of acid deposition on northern hardwood forests. 2015 Hubbard Brook Annual Cooperators Meeting : Biogeochemistry Drivers of trends and variation in tree-ring C and O isotopes at Watershed 3 Matt Vadeboncoeur, University of New Hampshire, matt.vad@unh.edu As part of a multi-site project across the northeast, we examined long-term trends and variability in hydrologic records from seven forested small watersheds, including Hubbard Brook watershed 3. ET has declined ~10% over 50+ years at both W3 and at Fernow, but not at the other sites we examined, which mostly have shorter records. Combining the meteorological and hydrological records with annual-resolution chronologies of wood growth and C and O stable isotope ratios for the dominant tree species at each site should allow us to distinguish among the various potential physical and biological drivers for these changes, which range from changes in growing season water availability, vapor pressure deficit, production, and plant physiology. Water use efficiency has increased in all species and sites, due to increasing atmospheric C concentrations. We found strong relationships among ET, tree growth, water use efficiency, and climate variables at some sites, but at Hubbard Brook surprisingly little of the isotopic (and presumably physiological) variation among years is explained by these same metrics. Growth rate and water-use efficiency changes in Watershed 1 maple and birch Stacie Powers, University of New Hampshire, sls78@wildcats.unh.edu Acid deposition in soils from pollution has limited growth in northern forests. Sugar maple and yellow birch are two species that have not been as studied when compared to other species such as red spruce or beech. There have been studies done on overall biomass of the calcium-fertilized watershed and I took a different approach with dendrochronology using a Velmex platform to read and cross-date tree rings using COFECHA to estimate the growth rate after the calcium fertilization. Isotopic methods were used to find CO2 ratios among the tree rings to calculate water use efficiency after the calcium fertilization. I extracted α-cellulose from various years after the fertilization from the tree cores. This was conducted in order to determine the δ 13C ratios to explain how much carbon was being exchanged from the canopy to the atmosphere each year. Size-Frequency and Temporal Analysis of the Concentration of Bulk Precipitation Chemistry at HBEF Chris Barton, Wright State Univ. and Columbia Univ., chris.barton@wright.edu Size-Frequency distribution and spectral density analysis of the concentration of Ca, Cl, Mg, K, Na, SO4, NO3, and pH in bulk precipitation samples collected at the RG 11 site. Size-frequency is found to be a power function distribution for all chemical species with most of the deposition resulting from the small events. Spectral density analysis of the time series of chemical species concentrations, at scales larger than gaps in the data, shows the temporal input to be internally correlated for each species, not a white noise. 1200 years of changing elemental concentrations in sediments of Mirror Lake, New Hampshire Kendra McLauchlan, Kansas State University, mclauch@ksu.edu Over the last decade, a dramatic decline of forest growth has been recorded in Hubbard Brook Experimental Forest (HBEF), a temperate hardwood forest in New Hampshire, USA. This decline of forest growth was coupled with a large decline of Ca availability, which suggests that chronic levels of acid rain may be reducing calcium availability to the point where it is becoming a limiting nutrient. Despite the recent potential importance of calcium availability, it is unknown whether recent changes in calcium availability are unique or part of a longer scale pattern that was interrupted by human activities over the past two centuries. To better understand long-term trajectories of elements such as Ca, we report a record of the dynamics of 20 elements over the last millennia based on X-ray fluorescence of Mirror Lake sediments, situated in the HBEF. Before European settlement in the region, there were clear long-term trajectories of elemental availability. From 876 to 1800 AD, Ca (r2 = 0.9) along with 6 other elements declined linearly in concentrations with time, while 4 other elements increased over time. Between 1250 and 1500 AD, 7 major disturbances were signified by marked changes in sediment concentrations of 3 elements (Si, P, and Mg). The European settlement period is well marked by differences in concentrations of several different elements. It also appears that there was an inflection point in many elemental trajectories with elements such as Pb and S declining after approximately 1970. In all, it appears that Ca availability was declining before European settlement and modern values are now close to pre-settlement values. Mineral soil nitrogen dynamics across a forest chronosequence Colin Fuss, Cary Institute of Ecosystem Studies, fussc@caryinstitute.org The mineral soil is a large and heterogeneous pool of nitrogen for which change over time is difficult to measure. We are conducting a variety of measurements and experiments in order to determine differences in nitrogen cycling processes in mineral soils as a function of forest age, with the hypothesis that young forests can mine N from the soil in order to meet growth demands and in older forests which have reached peak biomass, N reaccumulates in soil until a saturation. Presented here will be preliminary results from forests of differing ages, including soil water N fluxes and soil enzyme activity, as well as an update on the new experiments in progress. Denitrification and the Peter Groffman, Cary Institute of Ecosystem Studies, groffmanp@caryinstitute.org This talk will review multiple studies that address the question of if increases in denitrification have contributed to the long-term decline in nitrate concentrations in Hubbard Brook streams. These studies include analyses of just where and when denitrification might be occurring and if rates are high enough to have a significant effect on watershed nitrate export. Century-scale variations in ecosystem N pools and isotopic composition Christine Goodale, Cornell Univ., clg33@cornell.edu The enormous size and spatial heterogeneity of soil N regularly impede study of its role as a N source or sink over the course of forest succession. We have recently completed measurements of soil and tree stocks of ecosystem N and 15N patterns across three stands of varying time since harvest: W4, west of W6, and Mt. Moosilauke old-growth. So far, measurements show enormous soils with substantial site-to-site differences in soil N stock and 15N patterns, but that plant 15N varies more by tree species than by site. At Mt. Moosilauke, additional measurements of treering N accumulation and isotopic composition over the last century suggest an increase in tree N accumulation in recent decades, along with shifts in 15N indicating either a slowing of the N cycle or the impact of a distinctive N source. Response of Soil Process to the Effect of Whole-Tree Clear-Cutting Using PnET-BGC Mahnaz Valipour, Syracuse University, mvalipou@syr.edu Abstract Clear-cutting results in acidification and nutrient loss from northern forest landscapes. An integrated biogeochemical model, PnET-BGC, is applied to simulate long term interactive effects of whole-tree clear-cutting and atmospheric deposition on soil process and streamwater chemistry at the Hubbard Brook Experimental Forest (HBEF). This new application of the model provides an opportunity to not only evaluate temporal patterns of nutrients in soil solution, but also their spatial patterns across different horizons of forest soil coupled with streamwater chemistry. I will examine the response of soil process to a commercial whole-tree clear-cut in watershed 5. Simulation results for watershed 5 will be compared to the reference watershed which was not cut to assess changes in nutrient cycling after logging. Also, simulated values will be compared to field observations and previous analysis conducted based on experiments, to evaluate model results and quantify major sources and sinks of leaching nutrients throughout a watershed after a land disturbance. Information Management at Hubbard Brook: Annual Update Mary Martin, UNH, mary.martin@unh.edu The confluence of art, music and science at long-term ecological research sites: A new initiative Lindsey Rustad, UNH, lrustad@fs.fed.us The Waterviz at Hubbard Brook project, introduced at the 2014 Annual Meeting, continues to move forward in developing a new paradigm of engagement between the Arts and Sciences. This project uses insights from multiple disciplines to encode high volume and frequency ecological data in new ways, in order to better discover underlying pattern and process. In so doing, we hope to engage a broader, more diverse audience in understanding, and ultimately posing solutions to complex regional, and global environmental problems. Current products from this work include online digital visualization and sonification tools that display multi-dimensional realtime ecological data generated from environmental sensor arrays at Hubbard Brook. Waterviz at Hubbard Brook is a case study designed to demonstrate how the full intellectual integration of Arts and Sciences can help to provide a deeper level of understanding about the environments we live and work in.