UNIVERSITY OF CALIFORNIA Los Angeles Holocene Peatland Carbon Accumulation, Ecology ...

168 Pages·2013·30.93 MB·English

by  James Holmquist

UCLA
UCLA Electronic Theses and Dissertations
Title
Holocene Peatland Carbon Accumulation, Ecology, and Hydrology in the Canadian James
Bay Lowlands
Permalink
https://escholarship.org/uc/item/59c4n0gk
Author
Holmquist, James R.
Publication Date
2013

Peer reviewed|Thesis/dissertation
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University of California
UNIVERSITY OF CALIFORNIA
Los Angeles

Holocene Peatland Carbon Accumulation, Ecology, and Hydrology in the Canadian
James Bay Lowlands

A dissertation submitted in partial satisfaction of the requirements for the degree Doctor
of Philosophy in Biology

by

James Robert Holmquist

2013
© Copyright by
James Robert Holmquist
2013

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ABSTRACT OF THE DISSERTATION

Holocene Peatland Carbon Accumulation, Ecology, and Hydrology in the Canadian
James Bay Lowlands

by

James Robert Holmquist
Doctor of Philosophy in Biology
University of California, Los Angeles, 2013
Professor Glen MacDonald, Chair

Northern peatlands contain some of the largest terrestrial stores of organic soil carbon
(C) which may grow due to increases in productivity, or decline due to higher decay
under projected warming and drought scenarios. However, models of peatland growth
lack data on basic peatland history for the remote James Bay Lowlands (JBL) region of
Canada, as well as the relationships between climate and productivity, and the history
of Holocene precipitation. This dissertation presents C accumulation, vegetative
macrofossil, and proxy-climate reconstruction data from eight previously unpublished
sites in the JBL, as well as synthesizes currently available data. Peatlands in the JBL
initiated lagging the retreat of the Laurentide ice sheet, and the drainage of glacial lakes
by an average of 2,900 years. Most of the peatlands studied initiated as mineral rich
fens, which transitioned to nutrient poor bogs an average of 3,800 years after they

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initiated. Over the Holocene they have acted as a sink of CO , accumulating between
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71.5 and 171.2 kgC m-2, with median long-term apparent C accumulation rates
(LARCA) ranging from 13.8 to 31.6 gC m-2 yr-1. Peatland C accumulation was variable
within and between sites, but was driven by productivity rather than decay during the
late-Holocene. The depths of late-Holocene peat deposits correlate positively with
growing season length, and photosynthetically active radiation, and were negatively
affected by permafrost occurrence. A single site provides evidence for a relatively dry
pre-Holocene Thermal Maximum period, and a relatively wet Holocene Thermal
Maximum, with a small but positive influence of water table depth on LARCA. Although
there was some variation due to site-specific conditions, multiple sites indicate that the
warm Medieval Climate Anomaly was a wet period in the JBL, consistent with modern
precipitation anomalies, whereas the Little Ice Age was dry. The Little Ice Age may
have been locally complex due to precipitation variability, or the formation of permafrost.
On the short term, peatland C-stores may grow faster if temperature and seasonality
changes occur within their physiological and ecological limitations. However long-term
peatland stability in the area will likely be dependent on precipitation, which may
fluctuate due to the positions of the Arctic and Pacific fronts, and stochastic interactions
between the atmosphere and sea surface temperatures.

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The dissertation of James Robert Holmquist is approved

Thomas W. Gillespie
Philip W. Rundel
Lawren Sack
Glen M. MacDonald, Committee Chair

University of California, Los Angeles
2013

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To Mom and Dad, for instilling the values of curiosity and perseverance in me, and for
giving me everything that I need to succeed.

and to Jennifer Sargent for making the last five years the best of my life.

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Table of Contents
Abstract…………………………………………………………………………………...…….(ii)
List of abbreviations……………………………………………………………………...……(x)
List of figures and tables.………………………………………………………….….……..(xii)
Acknowledgements……………………………………………………………...…………..(xx)
Curriculum vitae……………………………………………………….…………………….(xxi)
1. Introduction…………………………………………….……………………………………(1)
2. Peatland Initiation, Succession and Carbon Accumulation in the James Bay
Lowlands……………………………………………………………………………….(9)
2.1 ABSTRACT………………………………………………………………………..(9)
2.2 INTRODUCTION……………………………………………………………...…(10)
2.3 MATERIALS AND METHODS…………………………………………………(13)
2.3.1. Field Sites and Previously Published Sites………………………..(13)
2.3.2. Age Depth Modeling………………………………………………….(18)
2.3.3. GIS Data……………………………………………………………….(22)
2.3.4. Macrofossil Analysis………………………………………………….(23)
2.3.4. Soil C Estimates……………………………………….…………..…(23)
2.4 RESULTS………………………………………………………………………...(24)
2.4.1. Peatland initiation and succession in the JBL…………..….……..(24)
2.4.2. Carbon Accumulation in the JBL……………………………………(35)
2.5. DISCUSSION……………………………………………………………………(38)
2.5.1. Geographic patterns of Peat Initiation and Succession…………..(38)

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2.5.2. Carbon Storage and LARCA………………………………………..(40)
2.6. CONCLUSION………………………………………………….….…………...(43)
3. Climate Drivers for Late-Holocene Vertical Peat Accumulation in the Hudson and
James Bay Lowlands………………………………………………………………..(44)
3.1. ABSTRACT………………………………….…………………………………..(44)
3.2. INTRODUCTION………………………………………………………………..(44)
3.3. MATERIALS AND METHODS………………………………………………...(48)
3.3.1. Average apparent rate of C accumulation…………………………(49)
3.3.2. Statistical Analysis……………………………………………………(49)
3.4. RESULTS………………………………………………………………………..(50)
3.4.1. 2 ka Soil C in JBL…………………………………………………….(50)
3.4.2. Climate and 2 ka Depth……………………………………………...(54)
3.4.3 Permafrost Occurrence and Peat Depth……………………………(61)
3.5. DISCUSSION……………………………………………………………………(62)
3.5.1. C Accumulation in the JBL…………………………………………..(62)
3.5.2. MAAT, GDD and PAR as Drivers of Post-2 ka Vertical Peat
0 0
Accumulation…………………………………………………………(63)
3.5.3. The Effect of Permafrost on Peat Depth…………………………...(66)
3.6. CONCLUSION…………………………………………………………………..(67)
4. Mid to Late-Holocene changes in Hydrology, Peatland Ecology, and Carbon
Accumulation in the Canadian James Bay Lowland………………..……………………(69)
4.1. ABSTRACT……………………………………………………………………...(69)
4.2. INTRODUCTION………………………………………………………………..(70)

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4.3. MATERIALS AND METHODS…………………………………….…………..(74)
4.3.1. Study site and core information…………….………..……………..(74)
4.3.2. TA processing………………………………………...………………(77)
4.3.3. Statistics……………………………………………………………….(79)
4.4. RESULTS………………………………………………………………………..(80)
4.4.1. TA and WTD…………………………………………………………..(81)
4.4.2. WTD changes associated with Macrofossil and LARCA
Record………………………………………………………………...(83)
4.5. DISCUSSION……………………………………………………………………(85)
4.5.1. Mid-Holocene WTD Changes……………………………………….(85)
4.5.2. Late-Holocene WTD changes……………………………………….(87)
4.5.3. Vegetation Changes in the Mid-Holocene…………………………(89)
4.5.4. Correlation between WTD and LARCA…..………………………..(90)
4.6. CONCLUSIONS………………………………………………………………...(92)
5. Impact of the Medieval Climate Anomaly, Little Ice Age, and Recent Warming on
Hydrology and Carbon Accumulation in the James Bay Lowlands…………….(93)
5.1. ABSTRACT……………………………………………………………………...(93)
5.2. INTRODUCTION………………………………………………………………..(94)
5.3. MATERIALS AND METHODS………………………………………………...(96)
5.4. RESULTS………………………………………………………………………..(99)
5.4.1. TA Assemblages…………………………………………………….(100)
5.4.2. WTD…………………………………………………………………..(106)
5.4.3. TA assemblages, WTD, and LARCA……………………………..(107)

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