Hubbard Brook Long Term Ecological Research Program

The Hubbard Brook Long Term Ecological Research (LTER) program is part of a national network of long-term ecological research sites. Established as an LTER in 1988, the focus of research has consistently been on the impact of disturbance on the Northern Forest.  The administrative home of the Hubbard Brook LTER project is the Cary institute of Ecosystem Studies, and the project has 36 co-Principal Investigators at 20 collaborating institutions.  

We take a broad view of disturbance, including disturbance from air pollution, climate change, forest harvest and biological invasions.  Research in the LTER encompasses field and laboratory studies, watershed-scale and plot-scale experiments, comparative studies with other sites in the region and in the LTER network, and modeling studies. Our long-term core measurements include hydrology, meteorology, air and precipitation chemistry, streamwater quantity and chemistry, vegetation, soils and soil solution chemistry, birds and insects.  

Some examples of our current research:

  • We are investigating the legacies of acid rain through a long-term experiment in which calcium was added to an entire watershed to replace the calcium stripped from the soil by decades of acid deposition. Results so far indicate that the calcium addition reversed the decline of the forest, improved the health of sugar maple and red spruce, increased decomposition, decreased carbon and nitrogen storage in the forest floor, and caused an increase in leaching losses of nitrogen in streamwater.
  • Our measurements show that as the climate warms, the early spring season between the disappearance of the snowpack and the growth of leaves on the trees is getting longer.  Our research is attempting to understand how the change in this critical period affects hydrological and gaseous nutrient losses and the performance of spring ephemeral flowers and other understory plants.
  • Climate change at Hubbard Brook involves both a reduction in the snowpack and warming of soils in the plant growing season.  A plot-scale experiment examines the interaction between these two aspects of climate change in a mixed hardwood forest.
  • Although most of the soils at Hubbard Brook can be classified as spodosols, the interaction of hydrology and topography produces a range of types of spodosol across the Hubbard Brook valley, We are working to be able to predict the distribution of spodosol types and determine the influence of this soil variation on ecosystem function.
  • The forests at Hubbard Brook are currently affected by a very damaging invasive forest pest, the beech bark disease, and two other invasive pests (hemlock woolly adelgid and emerald as borer) are likely to enter the forest in the coming years.  We are investigating the consequences of these pest invasions for the structure and function of the forest.
  • The primary consumers in the aboveground food web are caterpillars, and those caterpillars are the main food supply for the songbirds of the forest.  We are investigating the effects of climate change on the synchrony among the timing of leaf growth, caterpillar development, and migratory bird arrival and nesting.

Our work also includes educational and outreach efforts aimed at undergraduates, graduate students and informal science education for interested adults in the region.   We hold roundtable discussions with stakeholders to discuss the results and implications of our science, and we engage with policy makers in the state and federal government.

LTER Proposals:

  • HBR LTER I (1988; NSF Award #8702331)
  • HBR LTER II (1992; NSF Award #9211768)
  • HBR LTER III (1998; NSF Award #9810221)
  • HBR LTER IV (2005; NSF Award #0423259)
  • HBR LTER V (2010; NSF Award #; )
    • HBR_2011_SupplementProposal.pdf
    • HBR_2012_SupplementProposal.pdf
  • HBR LTER VI (2016; NSF Award #)

LTER Reports

  • HBR_2011_AnnualReport.pdf
  • HBR_2012_AnnualReport.pdf
  • HBR_2013_AnnualReport.pdf
  • HBR_2015_AnnualReport.pdf
  • HBR_2016_AnnualReport.pdf