Harvard Forest On-Going Research Projects

Harvard Forest Research

Measuring soil carbon in SIMES tract plots

Principal Investigator: Adrien Finzi
Boston University: May 10 2008 - Sep 10 2009:

Abstract:
The hemlock wooly adelgid is transforming the southern New England landscape, converting late-successional conifer stands into early successional hardwood stands composed primarily of black birch. Hemlock forests store a lot of carbon, particularly in soils as a result of a thick accumulation of partially decomposed organic matter on the forest floor. I am interested in continuing to work with the HF on a project quantifying the change in carbon stocks associated with the loss of hemlock. My primary sampling interest is in quantifying soil C stocks. Together with the data collected by the HF, I will construct C budgets for different stages of hemlock loss.

Since 2008, I have been using a chronosequence approach to document the loss of carbon, with three stands present at Harvard Forest: a) old-growth hemlock at the Hadley eddyflux tower site, b) second-growth hemlock, and c) girdled hemlock, both at the Simes tract. Studying old growth hemlock stands provide an indication of the maximum C storage capacity for this species. Second growth stands dominate the landscape, so comparing second growth to old growth C storage indicates how much additional C could be stored if the wooly adelgid were not present. The girdled stand enables me to quantify the initial stage of C loss associated with the replacement of hemlock by birch. There are two other stands being studied that are outside of the Harvard Forest. Burnham Brook at the Connecticut River Valley is being used to represent the presence of black birch saplings after the HWA infestation. Harvard Conservation Trust in Harvard, MA, has 2nd-growth black birch-dominated stands that represent a more mature forest after the infestation.

For each treatment stand age, I have located 4 replicate plots. At each site I have sampled the surface organic horizon and the mineral soil to a depth of 45 cm. This sampling was achieved by locating three 3 replicate 30x30m sampling locations within each plot. Within this 30x30m sampling area I collected 10x10cm monolith of the forest floor, and directly beneath this monolith, a 5-cm diameter corer was used to remove mineral soil. This amount of soil sampling has not caused any detrimental effect on other studies, and were marked by flagging. In the lab, these samples were sieved and are now being used to estimate (1) bulk density, (2) %C, and (3) %N. I have archived the air dried soil for future analyses that might be interested in this study. Time and space permitting I will freeze soils a -80 oC to preserve the possibility of future microbial analyses.

An inventory was also done at the selected plots with the identification of tree species and their respective DBH. Some of the trees had been previously tagged by other researchers at Harvard Forest and their data were later obtained in order to complete the inventory information.

We have thus far found a large reduction in organic horizon mass and fine root biomass when comparing primary hemlock forest (Hadley tower site, Harvard Forest) with the 13 year old black birch stand (CT River Valley). There was however a substantial recovery of fine root biomass. Fine root biomass in the ~60 year old black birch stand (Harvard Trust) was the same as that in the second growth hemlock stand (Simes Tract), although organic horizon mass remained lower in the black birch stand.

This field season I would like to go back to the plots I have been studying to focus on coarse woody debris (CWD). Minda Berbeco, from Tufts University, will be collaborating to this part of the project as her research focuses on such topic. I would like to obtain debris samples with the use of increment borers for solid debris and a slide hammer or a saw in the case of hollow debris. During the CWD study, I will also be counting the saplings in the previously set plots.

Secondly, I would like to set up litter baskets in these plots to look at litter quality and turnover rate. The prediction of net primary productivity (NPP) can be partially obtained with this type of data collection. An additional part to this prediction is the use of tree cores. Tree cores have been obtained from previous projects and I would like to have access to them and study different growth rates for the different sites.
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	Harvard Forest Research Measuring soil carbon in SIMES tract plots Principal Investigator: Adrien Finzi Boston University: May 10 2008 - Sep 10 2009: Abstract: The hemlock wooly adelgid is transforming the southern New England landscape, converting late-successional conifer stands into early successional hardwood stands composed primarily of black birch. Hemlock forests store a lot of carbon, particularly in soils as a result of a thick accumulation of partially decomposed organic matter on the forest floor. I am interested in continuing to work with the HF on a project quantifying the change in carbon stocks associated with the loss of hemlock. My primary sampling interest is in quantifying soil C stocks. Together with the data collected by the HF, I will construct C budgets for different stages of hemlock loss. Since 2008, I have been using a chronosequence approach to document the loss of carbon, with three stands present at Harvard Forest: a) old-growth hemlock at the Hadley eddyflux tower site, b) second-growth hemlock, and c) girdled hemlock, both at the Simes tract. Studying old growth hemlock stands provide an indication of the maximum C storage capacity for this species. Second growth stands dominate the landscape, so comparing second growth to old growth C storage indicates how much additional C could be stored if the wooly adelgid were not present. The girdled stand enables me to quantify the initial stage of C loss associated with the replacement of hemlock by birch. There are two other stands being studied that are outside of the Harvard Forest. Burnham Brook at the Connecticut River Valley is being used to represent the presence of black birch saplings after the HWA infestation. Harvard Conservation Trust in Harvard, MA, has 2nd-growth black birch-dominated stands that represent a more mature forest after the infestation. For each treatment stand age, I have located 4 replicate plots. At each site I have sampled the surface organic horizon and the mineral soil to a depth of 45 cm. This sampling was achieved by locating three 3 replicate 30x30m sampling locations within each plot. Within this 30x30m sampling area I collected 10x10cm monolith of the forest floor, and directly beneath this monolith, a 5-cm diameter corer was used to remove mineral soil. This amount of soil sampling has not caused any detrimental effect on other studies, and were marked by flagging. In the lab, these samples were sieved and are now being used to estimate (1) bulk density, (2) %C, and (3) %N. I have archived the air dried soil for future analyses that might be interested in this study. Time and space permitting I will freeze soils a -80 oC to preserve the possibility of future microbial analyses. An inventory was also done at the selected plots with the identification of tree species and their respective DBH. Some of the trees had been previously tagged by other researchers at Harvard Forest and their data were later obtained in order to complete the inventory information. We have thus far found a large reduction in organic horizon mass and fine root biomass when comparing primary hemlock forest (Hadley tower site, Harvard Forest) with the 13 year old black birch stand (CT River Valley). There was however a substantial recovery of fine root biomass. Fine root biomass in the ~60 year old black birch stand (Harvard Trust) was the same as that in the second growth hemlock stand (Simes Tract), although organic horizon mass remained lower in the black birch stand. This field season I would like to go back to the plots I have been studying to focus on coarse woody debris (CWD). Minda Berbeco, from Tufts University, will be collaborating to this part of the project as her research focuses on such topic. I would like to obtain debris samples with the use of increment borers for solid debris and a slide hammer or a saw in the case of hollow debris. During the CWD study, I will also be counting the saplings in the previously set plots. Secondly, I would like to set up litter baskets in these plots to look at litter quality and turnover rate. The prediction of net primary productivity (NPP) can be partially obtained with this type of data collection. An additional part to this prediction is the use of tree cores. Tree cores have been obtained from previous projects and I would like to have access to them and study different growth rates for the different sites. :
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