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Northern Research Station
11 Campus Blvd., Suite 200
Newtown Square, PA 19073
(610) 557-4017
(610) 557-4132 TTY/TDD

Clean Air and Water

Atmospheric Exchange
AmeriFlux - Howland Site

[image:]  Howland Ameriflux Site - tower viewed from aboveResearch Issue

The goal of this project is to develop a capacity to predict how future climatic change may affect carbon cycle processes and carbon storage in an evergreen, sub-boreal forest located in the northeastern US. 

Our Research

We are using eddy covariance measurements (direct measurements of forest CO2 uptake and loss) made from a cluster of four towers, as well as extensive soil and ecological measurements, to investigate above- and below-ground controls on forest C cycling.  Our first aim is to continue high-quality AmeriFlux contributions from this site by measuring CO2, heat, and water vapor fluxes, biomass growth, LAI, and soil respiration in stands representing a range of forest ages and management histories. A second objective is to investigate the coupled nitrogen and carbon dynamics of this forest system to address the impact of N deposition on forest C sequestration. A third objective is to carry out detailed measurements of soil radiocarbon content to narrow uncertainties in estimates of the residence times of belowground C pools that may be susceptible to climate change on decadal scales.  A final objective is to develop state-of-the-art inverse analyses and data-model fusion techniques to integrate into a common modeling framework our measurements and understanding of NEE, primary productivity, and above- and below-ground respiration with the aim of identifying the degree of model complexity that can be informed by our measurements, increasing our ability to objectively estimate model parameter values based on measurement data.

Expected Outcomes

Our research is expected to narrow uncertainties relating to how forest ecosystem carbon exchange and storage will respond to a changing climate. Major outcomes of the project will be (1) a detailed characterization of C-cycle processes in a northern forest ecosystem at Howland; (2) prognostic models to forecast future C-cycle processes; and (3) defensible estimates of the uncertainties in measured and modeled C fluxes and pools.

Research Results

More details about this research: Howland Forest

Piao, S., P. Ciais, P. Friedlingstein, P. Peylin, M. Reichstein, S. Luyssaert, H. Margolis, J. Fang, A. Barr, A. Chen, A. Grelle, D. Hollinger, T. Laurila, A. Lindroth, A.D. Richardson, T. Vesala. 2008. Net carbon dioxide losses of northern ecosystems in response to autumn warming. Nature 451(7174):49-53.

Richardson, A.D. and D.Y. Hollinger. 2007. A method to estimate the additional uncertainty in gap-filled NEE resulting from long gaps in the CO2 flux record. Agricultural and Forest Meteorology 147:199-208.

Gaige, E., D.B. Dail, D.Y. Hollinger, E.A. Davidson, I.J. Fernandez, H. Seivering, A. White, and W. Halteman. 2007. Changes in canopy processes following whole-forest canopy nitrogen fertilization of a mature spruce-hemlock forest. Ecosystems 10:1133-1147.

Richardson, A.D., D.Y. Hollinger, J.D. Aber, S.V. Ollinger and B.H. Braswell. 2007. Environmental variation is directly responsible for short-but not long-term variation in forest-atmosphere carbon exchange. Global Change Biology 13:788-803.

Davidson E.A., A.D. Richardson, K.E. Savage, and D.Y. Hollinger. 2006. A Distinct Seasonal Pattern of the Ratio of Soil Respiration to Total Ecosystem Respiration in a Spruce-Dominated Forest. Global Change Biology 12:230-239.

Gove, J.H. and D.Y. Hollinger. 2006. Application of a dual unscented Kalman filter for simultaneous state and parameter estimation in problems of surface-atmosphere exchange. Journal of Geophysical Research, 111, D08S07.

Hollinger D.Y.  and A.D. Richardson. 2005. Uncertainty in eddy covariance measurements and its application to physiological models. Tree Physiology 25:873-885.

Hollinger D.Y., J. Aber, B. Dail, E.A. Davidson, S.M. Goltz, H. Hughes, M. Y Leclerc, J.T. Lee, A.D. Richardson, C. Rodrigues, N.A. Scott, D. Achuatavarier, and J. Walsh. 2004. Spatial and temporal variability in forest-atmosphere CO2 exchange. Global Change Biology, 10:1689-1706.

Research Participants

Principal Investigator

Research Partners

Last Modified: 12/22/2008