Natalie van Doorn and colleagues report on a 10-year resurvey of a valley-wide plot network (371 plots across 3,160-ha) in Hubbard Brook Valley, New Hampshire (online in advance of print in the Canadian Journal of Forest Research). The goal of this project was to quantify recent trends in tree biomass and demography. The results from this paper confirm earlier reports that the forest at Hubbard Brook is no longer aggrading. There was no significant change in live tree biomass between 1995/6 and 2005/6. However, there were salient shifts in relative dominance of the canopy species (in particular, significant drop in yellow birch biomass was matched by increases in balsam fir and red spruce). A look into the tree demography revealed that mortality significantly exceeded recruitment for yellow birch and paper birch. For the major tree species, there was no instance of recruitment significantly exceeding mortality. Relative growth rates were greater than 1.5% per year for sugar maple, red spruce, and beech. Although effects of novel disturbances documented on a regional level have not led to directional changes in tree demography at Hubbard Brook, the authors suggest that these novel stressors are depressing the biomass potential of the forest.
Read more about the long-term Hubbard Brook Valley plot network