Abstract
A 6-m vibracore taken from the Great Bog in Belgrade, Maine, was sampled for pollen analysis at 10-cm intervals. Samples were processed in the laboratory using standard techniques developed by Faegri and Iversen. The sediment in the sample was reduced to a residue of pollen which was mounted on microscope slides. A minimum of 300 pollen grains was identified and counted at each level using a compound microscope at 400x magnification. Five radiocarbon dates were taken from the core at stratigraphic boundaries. Lastly, pollen concentration and pollen accumulation rates were calculated. The uppermost 3.8 m of the core is fine peat; this overlies 1.5 m of lacustrine clay below which are additional organic deposits. Approximately 1.5 m of silty clay was lost from the bottom of the core during coring. 14C dates from above and below the clay are statistically equivalent, suggesting very rapid deposition; a basal date on the core is also statitically equivalent in age , but is probably contaminated. Rapid deposition of the clay could have been caused by mass wasting or upland denudation. Dramatic erosion of the uplands could be caused by clearing of vegetation by a forest fire, but this is not supported by any significant, charcoal in the core. Additional work is planned to delimit the areal extent of the clay unit and resolve the apparent dating anomalies in the lower core. Although the post-glacial pollen record generated in this study at Great Bog is incomplete, it is highly detailed. The pollen record indicates that the Great Bog was an open embayment of Great Pond from 8,500 to 6,500 b.p. The change in the aquatic vegetation at the site from the open-water taxa Nuphar, Nymplwea, and Brasenia to Eriocaulon and abundant Sphagnum spores suggests that the water level at Great Bog may have dropped and subsequently allowed a Sphagnum mat to develop. It is possible that this occurred at the same time as a mid-Holocene drop in water level of lakes throughout Maine. Pinus dominated the regional vegetation also until 6,500 b.p. when Tsuga and Fagus appeared in significant percentages. Tsuga had a temporary demise around 4,000 b.p. that is recorded regionally and was possibly caused by a pathogen. At 30-cm depth, there was an increase in Ambrosia, which reflects agricultural clearing at the start of European colonization of this region.
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Claims 9
Claim · model-written summary
Pinus dominated the regional vegetation until 6,500 b.p.
PinusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Pinus dominated the regional vegetation also until 6,500 b.p.”
Claim · model-written summary
Tsuga and Fagus appeared in significant percentages in the pollen record after Pinus dominance.
- Outcome
- appeared in significant percentagese2
Tsuga_in_Humlamaden_1516.jpg?width=60){kind=small}
FagusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
_in_Humlamaden_1516.jpg?width=500)
Verbatim
e2“Tsuga and Fagus appeared in significant percentages”
Claim · model-written summary
Tsuga had a temporary demise around 4,000 b.p. that is recorded regionally.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Tsuga had a temporary demise around 4,000 b.p. that is recorded regionally and was possibly caused by a pathogen”
Claim · model-written summary
The Tsuga demise was possibly caused by a pathogen.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“Tsuga had a temporary demise around 4,000 b.p. that is recorded regionally and was possibly caused by a pathogen”
Claim · model-written summary
A drop in water level at Great Bog may have allowed a Sphagnum mat to develop.
SphagnumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“suggests that the water level at Great Bog may have dropped and subsequently allowed a Sphagnum mat to develop”
Claim · model-written summary
Ambrosia increased at 30-cm depth in the core.
AmbrosiaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“At 30-cm depth, there was an increase in Ambrosia, which reflects agricultural clearing at the start of European colonization of this region”
Claim · model-written summary
The Ambrosia increase reflects agricultural clearing at the start of European colonization.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“At 30-cm depth, there was an increase in Ambrosia, which reflects agricultural clearing at the start of European colonization of this region”
Claim · model-written summary
The Great Bog was an open embayment of Great Pond from 8,500 to 6,500 b.p.
Not reportedTaxon
Verbatim
e0“The pollen record indicates that the Great Bog was an open embayment of Great Pond from 8,500 to 6,500 b.p.”
Claim · model-written summary
Clay deposition at the Great Bog was very rapid.
- Outcome
- very rapid depositione6
Not reportedTaxon
Verbatim
e6“14C dates from above and below the clay are statistically equivalent, suggesting very rapid deposition”