Completed Projects
Eric A. Davidson, Woods Hole Research Center
David Hollinger, USDA Forest Service, Durham NH
Project Title: "Long-term CO2 exchange and biomass measurements in a spruce-hemlock stand near Howland, Maine, supporting regional-scale studies and ecosystem manipulation experiments"
***********************
PI: Russell R. Dickerson, University of Maryland
Project Title: "Sulfate-Coated Soot and Its Impact on Global Climate"
Figure 7: Absorption cross-section per particle vs. shell thickness. Blue dots represent the calculated Mie theory values for the core particles. They provide a reference point for comparison with the experimental values. Coated particles show an increase in absorption cross-section for each core size shown. The data has a linear fit showing positive slopes for all core sizes. The positive slope is indicative of absorption enhancement.
Figure 10: This graph demonstrates that as the soot core size increases, the amplification effect increases. The slope of the linear fit for each soot core data set has been plotted versus the core size. A positive slope indicates that increasing the core size increases the slope, therefore, the effect of the non-absorbing coating on the absorbing core is greater.
***********************
PI's: David R. Foster, Harvard University
Julian L. Hadley, Harvard University
Project Title: "Effects of forest age, soil drainage and interannual climate variation on deciduous forest carbon exchange: A comparison to long-term Harvard Forest measurements, in a contrasting forest type"
***********************
PI: Xuhui Lee, Yale University, Connecticut
Project Title: "Response of Soil Respiration to Rain"
***********************
Project Title: "Past, present & future of terrestrial CO2 flux in North-Eastern Forests: the role of ecophysiological responses, land-use history & disturbance legacies".
"In order of importance, the three principal causes of interannual variability in carbon uptake during the period were, (i) summer-time precipitation anomalies, (ii) spring-time temperature anomalies, and (iii) fall temperature anomalies".
***********************
PI's: J. William Munger, Harvard University
Steven C. Wofsy, Harvard University
PI Title: "Long-term response by the carbon budget of a mid-latitude deciduous forest to ecological processes, climate variations, and air pollutants"
***********************
PI's: Ruth K. Varner, University of New Hampshire
Patrick M. Crill, Stockholm University
Project Title: "High Frequency Measurements of CO2 Efflux from Forest Soil"
"The differences in soil CO2 efflux between the wetland margin, midslope and upland chambers were most pronounced after day 200 in the late summer/early fall"
"Soil CO2 efflux reached a maximum later in the year than total ecosystem respiration measured at the eddy covariance flux tower".
***********************
Ongoing Projects
PI: Mark O. Battle, Bowdoin College
Project Title:"Measurements of the O2-CO2 Stoichiometry of Terrestrial Ecosystems
***********************
PI: Brian Beckage, University of Vermont
Project Title: "Using historical change to predict future distribution of high elevation forests in northen New England"
***********************
PI's: Eric A. Davidson, The Woods Hole Research Center
Susan E. Trumbore, University of California, Irvine
Project Title: "Decadal-Scale Measurements of Decadal-Cycling Forest Soil Carbon"
***********************
PI: Jeffrey Dukes, University of Massachusetts, Boston
Project Title: "The Boston-Area Climate Experiment: A Gradient-based Approach for Characterizing Ecosystem Responses to Warming and Precipitation Change"
As the experiment is still under construction, there are no research highlights to date. Future highlights, research products, and publications will be made available at the BACE website: www.ecosystems.umb.edu/bace.html
************************
PI's: Christine L. Goodale, Cornell University, Ithaca NY
Scott C. Ollinger, University of New Hampshire, Durham NH
Project Title: "Effects of Future Changes in Climate and Atmospheric Composition on Forest Ecosystems across the Northeastern U.S.: Model Development, Testing, and Projections"
***********************
PI: Margot Kaye, Penn State University, Pennsylvania
Project Title: "Northeastern Forest regeneration in a warmer & wetter climate"
Figure 3. Soil respiration response to increased soil temperature in 4 treatment plots. The lower Q10 observed in heated and heated+irrigated plots could be the result of either microbial community acclimation to warming or change in the labile substrate pool (Bradford et al. 2007, Hartley et al. 2007).
*************************
PI's: Xuhui Lee, Yale University, Connecticut
Edward Patton, National Center for Atmospheric Research, Colorado
Project Title: "Influence of Boundary Layer Flow on Vegetation-Air Exchanges of Energy, Water and Carbon Dioxide"
*************************
PI: Jerry Melillo, Marine Biological Laboratory
Project Title: Effects of soil warming on the carbon and nitrogen cycles and their interactions in temperate forests; implications for land-atmosphere feedbacks
Figure 1. Total soil CO2 efflux partitioned into soil organic matter decay, root respiration, and fine root decomposition in kg/ha.
Figure 3. Heating increases soil respiration and carbon storage in vegetation. Effect of soil warming on the carbon balance of the forest stand as the difference between the warming-induced carbon loss from the soil and the gain in the perennial tissues of the canopy trees. Values represent the effect of warming on cumulative vegetation carbon (gain in woody carbon in trees minus loss in fine root biomass) and the soil organic matter decay (total respiration minus root respiration minus decay of fine root biomass).
PI: Paul R. Moorcroft, Harvard University
Project Title: "Impacts of climate variability and change on forest structure, composition, and function in the Northeastern United States"
Figure 1. Effects of climate, atmospheric pollutants, topography, and stand structure on patterns of tree mortality in the Eastern United States. All the realtionships shown are statistically significant.
PI's:J. William Munger, Harvard University
Steven C. Wofsy, Harvard University
PI Title: "Analysis of long-term trends and anomalies in CO2 and H2O exchange at a NE US mixed deciduous forest in response to climate varabilities"
Figure 1. Upper panel: Total number of growing days per year - defined as days with a net negative daily carbon balance. A linear fit to the observations yields a slope of 1.5 days per year with an R2 of 0.48
Lower panel: Total annual NEE at the Harvard Forest EMS tower for calendar years 1992 - 2007. Negative values are uptake of CO2 by the forest. The dashed line shows least-squares trend with a slope of -0.24 Mg-C ha-1 y-1 per year. Note the correspondence of peaks in growing season length in 2001 and 2007 with peaks in total annual NEE for those years.
******************************
PI: Andrew Richardson, Harvard University, Eric Davidson, Woods Hole Research Center, and Bryan Dail, University of Maine
Project Title: "Reducing uncertainty about the effects of climatic variation on forest ecosystems by measuring, modeling, and analyzing intermediate-turnover carbon pools"
Figure 2. Modeling forest-atmosphere exchange at Howland using the DALEC model, running at a twice-daily time step and constrained with multiple data streams. Results are shown for end of 4-year calibration period (open circles) and also 4 years later, following validation period (closed circles). Error bars indicate 90% confidence intervals based on X2 test.
Model runs, identified by number on x-axis, indicate the data streams included in cost function and X2 test criteria, as follows: (1) Daytime NEE fluxes only; (2) Daytime and nighttime NEE fluxes: (3) (2) plus "reality constraint" (neither Cw nor CSOM pool collapses by more than 100 g C m-2 y-1 over 4-year calibration period); (4) (3) plus soil respiration; (5) (3) plus LAI; (6) (3) plus litterfall; (7) (3) plus cumulative woody biomass increment; (8) All constraints simultaneously. Panels are as follows (all units in g C m-2): iNEE, time-integrated net ecosystem exchange; iGPP, integrated heterotrophic respiration; iRa, integrated autotrophic respiration; iRsoil, integrated soil respiration; idCw, cumulative change in woody biomass pool; idCsom, cumulative change in soil C pool; LAI, leaf area index.
Figure 3. Cumulative NEE, by year, when DALEC model, running at a twice-daily time step, is constrained using 1997-2000 tower CO2 fluxes, soild R fluxes, leaf area index, litterfall, and woody biomass increment data.
Shading indicates 90% confidence intervals on modeled integral, for calibration (dark) and validation (light periods. Circles and error bars indicate cumulative NEE estimated from half-hourly tower measurements gap-filled with an empirical model.
*******************
PI's: J. L. Sarmiento, Princeton University, C. Crevoisier, Princeton University, S. W. Pacala, Princeton University,
Project Title: Evaluation of ecosystem carbon dynamics in North America Using Hourly to Decadal Data on Local to Regional Scales
Figure 3. NPP difference map between the model output and the CASA data set. Panel 3(a) is the experiment with original parameter configuration which gives the best global NPP value, but with NPP too high in the high latitude and too low in the tropics compared to the CASA data. Panel 3(b) is the "dv2" configuration which resulted in very high NPP. Panel 3(c) is the first result after optimization and panel 3(d) is the final optimization
Figure 6. Comparison of LM3V model output with observed monthly mean CO2 flux from AmeriFlux dataset. 6 sites were selected with data before year 2000. Vegetation Type: Harvard Forest - temperate deciduous forest; Howland Forest Main - Boreal northern hardwood transitional forest; Walker Branch - Mixed species, broadleaved forest, deciduous forest; Bondville - Annual rotation cropland between corn (C4) and soybeans (C3); Metolius Old Pine - Evergreen needleleaf forest; Sky Oaks Old - Closed shrublands (Mediterranean type ecosystems); Wind River Crane - Evergreen needleleaf forest
PI's: Matthew Wallenstein, Richard Conant, and Eldor Paul, Colorado State University
Project Title: Annual Report: Parsing the mechanisms that drive soil decomposition responses to climate change: a test of the substrate depletion and microbial acclimation hypotheses.
Figure 1. Enzyme activities in January 2009 at the BACE experiment, showing differences between precipitation treatments (ambient temperature).
Figure 3. Multiple substrate induced respiration for BACE soils collected in August 2008.
