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.