Media Category: HBR

View of the greening-up canopy of the Bartlett Experimental Forest, a sister site to Hubbard Brook, from the top of a tower where carbon dioxide exchange in measured by the eddy covariance technique. The instrument in the foreground is a sonic anemometer. These measurements of the exchange of carbon dioxide between the forest and the atmosphere provide a direct measurement of forest productivity. Year-to-year variation in how much carbon dioxide the forest removes from the atmosphere is strongly related to the timing of the start and end of the growing season, with early spring leaf-out and delayed autumn senescence both tending to increase carbon uptake. Andrew Richardson Andrew Richardson

Ecosystems at Hubbard Brook have been subject to acid deposition for over 50 years, leading to the depletion of important nutrients, such as calcium, from the soils. We experimentally replaced the depleted calcium on an entire watershed by spreading a calcium-containing mineral from a helicopter. There was an almost immediate response by the vegetation, particularly sugar maple trees. The increased growth of sugar maple reversed the forest stagnation and decline that had been occurring previously and which continued to occur in a nearby reference watershed. Battles, J. J., T. J. Fahey, C. T. Driscoll, J. D. Blum, and C. E. Johnson. 2014

In the winter of 2016, the Hubbard Brook LTER, together with the US Forest Service Northern Research Station, created artificial ice storms of varying duration and intensity to probe the impacts of these dangerous and beautiful extreme events.