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East Haven, CT. 1999
Biomass Estimates for 1991 vs. 1999 | Estimated Productivity Based on Annual Tree Growth
The numbers given below are estimates. Wherever possible we applied equations developed from the geographical location closest to our sample area. However, many of our equations were produced in West Virginia, Maine, and the Upper Great lakes. It is easy to see that problems could arise from applying equations created for one site to another site with different conditions. See the Introduction for suggestions on how to minimize this error.
For comparative purposes, 1997 data from the 80 yr old forest at Watershed 6, Hubbard Brook, NH, is provided where appropriate
It was not clear from the source of our biomass equations whether or not leaves and twigs were included in the equations estimating above ground biomass (AB). Therefore, we have provided data from Hubbard Brook for biomass productivity both including and excluding leaves and twigs. All above-ground live tree biomass estimates are given in Mg/ha.
Biomass Estimates for 1991 vs. 1999
Saltonstall Ridge
|
1991 (Mg/ha) |
1999 (Mg/ha) |
Net Change (Mg/ha) |
Change per Year (Mg/ha) |
Net % change |
|
|
West Side |
148 |
147 |
-1 |
-.125 |
-0.6 |
|
East Side |
122 |
157 |
35 |
4.375 |
+22 |
|
Entire Ridge |
132 |
152 |
20 |
2.5 |
+13 |
Based on our estimates, above-ground live biomass at Saltonstall Ridge increased approximately 2.5 Mg/ha or 2,500kg/ha annually over the eight year period from 1991-1999.
Hubbard Brook
|
1997 |
|
|
Above Ground Biomass with Leaves/Twigs |
197 Mg/ha |
|
Above Ground Biomass without Leaves/Twigs |
193 Mg/ha |
Estimated Productivity Based on Annual Tree Growth
Saltonstall Ridge
|
1990 |
1991 |
Productivity per year |
1998 |
1999 |
Productivity per year |
|
|
1 mm Annual Growth |
130 |
132 |
2 Mg/ha |
150 |
152 |
2 Mg/ha |
|
2 mm Annual Growth |
127 |
132 |
5 Mg/ha |
147 |
152 |
5 Mg/ha |
To calculate productivity per year, we subtracted annual growth from each individual tree dbh and recalculated the forest biomass for previous years. We obtained annual growth rates from our tree ring data. Annual growth rates were estimated at between 1-2 mm per year. We modeled forest productivity at both 1 and 2mm growth per year.
We chose to estimate the change in annual biomass by calculating the previous years because we can assume that the trees measured in 1991 and 1999 were also alive in 1990 and 1998.
After calculating the yearly productivity for both 1 and 2 mm growth per year, we estimate that the annual productivity is between 2 to 5 Mg/ha per year, which averages to 3.5 Mg/ha per year.
* Biomass results are expressed in Mg / ha, or metric tons per hectare. 1 Mg = 1,000 kg = 1,000,000g
