Details of the
Hubbard Brook Phytosociology program

This page contains Tom's notes about the details of the forest dynamics phytosociology programming for the Bird Area. They are here as much for our remembrance of what we did as for the benefit of anyone else who needs to know the minutia.

 

There are a lot of quick notes:

1. "Sick" trees have crowns that appear to be yellowing or otherwise in decline.
2. "Standing dead" trees still have most of their branches.
3. "Standing snag" trees are dead without branches but with a bole left above dbh. 
4. "Fallen to ground" trees have broken off below breast height and are lying on the ground or are not yet broken, but leaning at an angle of less than 45 degrees to the ground.
5. Every other year from 1991 to 2001, all trees >10.0 cm dbh on the Birdline transects were accessed for health status. New trees that reach 10.0 cm dbh ("ingrowth") are tagged as they are found each survey year. By 2001, this dataset included almost 6000 stems we are following or have followed until they fell.
6. You should study the year-specific data documentation for the special details and access to the original raw tree by tree data.

 
More detailed notes:

1. Radial increment is calculated by subtracting the 1991 diameter measurement from the 2001 measurement and dividing by 2 to get the change in radius. This is done for each stem and the values for all stems under consideration are summed and divided by the total number of stems to get average radial increment. This is then divided by the 10 years between measurements to get average annual radial increment.

2. The ouput for this program is not organized by diameter class, so there is no doubling of trees 10.0 to 10.4 cm in this program as there is in many of the other calculators.

For any further questions, please email thomas.siccama@yale.edu.

Web page created November 2003
by Thomas Siccama and Ellen Denny