Forest Ecosystems In A Changing World


Reference Watersheds:

Whole Watershed Acidification Experiment:

Autumnal litterfall mass
Canopy architecture (2011)
Soil Chemistry (2011)
Lysimeter Data (2011-2014)
Root data (1991)
O Horizon root data (2012)
Fine root data (2013)

Long-Term Soil Productivity (LTSP) Experiment:

Tree inventory (2009)
Damage assessment (2011)
Lysimeter Data (1996-2010)

Long-term Monitoring:

Climatological, hydrological, and water chemistry data:

Rain chemistry data since 1978 (NADP site WV18):

Click here for NADP data

Dry deposition data since 1989 (CASTNET site PAR107):

Click here for CASTNET data

Smart Forest Real-Time Data for WS 4

Click here for Smart Forest data

Other data collected by forest service personnel are available by written request to Frederica Wood ( and include vegetation, litter fall, soil, and soil solution measurements.

Major Findings (click on images to enlarge)

There are strong links between precipitation chemistry at the Fernow and human activities – both the bad (industrial pollution) & the good (policies that mitigate air pollution).

Intersite NOx vs nitrateNitrate and sulfate concentrations in rain at the Fernow strongly correlate (R2 = 0.79) with EPA estimates of NOx and SOx emissions for the entire US.


History of nitrate in rainNitrate concentrations in rain have decreased ~48% since 1997 at the Fernow and reflect a similar decline in US NOx emissions.


The composition of tree species at the Fernow has changed, and the extent of change is related to management practices.

sugar maple trendsSugar maple increased despite declining populations at other locations in the northeastern US.



Management practices, or natural changes, which favor certain tree species might delay or accelerate the onset of nitrogen saturation.

trees and stream nitrateSmall watersheds with more sugar maple lose more nitrate in stream water. Those with more chestnut oak lose less nitrate in stream water.

nitrification two species
Small plots with more sugar maple produce more nitrate. Those with more chestnut oak produce less.



The growth response of trees to N additions is short-lived and species specific.

forest growthThe growth of trees at the Fernow was initially stimulated by additions of ammonium sulfate.  However, this stimulation was short-lived (~7 years) and not observed in plots dominated by red maple & sweet birch.

Increased nitrogen availability is associated with reduced tree species diversity.

tree species diversityIn untreated watersheds, more nitrate production is associated with fewer tree species. And experimental additions of ammonium sulfate have reduced the number of tree species from 11 to 9 species in a regenerating forest.

Long-term data from WS 4 contributes to an analysis of trends in stream nitrogen for forested catchments across the United States (see Argerich et al. 2013). (See video)