Peatlands, volcanoes and climate: Ecological and palaeoecological studies in Alaska and Scotland
Metadata
Show full item recordAbstract
This thesis investigates direct and indirect volcanic impacts on peatlands using
palaeoecological and ecological techniques. The primary approach used is
palaeoecological studies across tephra layers. A multi-proxy methodology was adopted
including testate amoebae, hurnification and outline macrofossil analysis supported by
radiocarbon dating. To allow quantitative interpretation of testate amoebae results a
transfer function model was developed for surface wetness and pH. To examine whether
it is justified to use tephra layers as evidence of volcanic activity an experiment was
carried out to investigate tephra taphonomy. Results show that tephra does move through
peat but the majority remains at the surface. In an attempt to characterise the
palaeoecological response to volcanic acid deposition an experiment was conducted
applying tephra and acids to a Scottish peatland. Results show drastic impacts on
peatland plants but impacts on other variables were more equivocal.
For the palaeoecological studies a series of peatland sites were sampled in
southeast Alaska and on the Kenai Peninsula in south-centra Alaska. A number of
microscopic and visible tephras were located and subjected to electron microprobe
analysis to aid their identification. Results show the great potential of microtephrochronology
to extend the distribution of tephra layers in Alaska. Furthermore,
results highlight the great size of several eruptions, improve the dating of others and
show the presence of previously unrecognised tephras. The macrofossil and testate
amoebae results show impacts associated with some tephras but not all. The hurnification
results are considered unreliable due to a methodological problem. The most likely cause
of the impacts is through volcanic acids and gases or other chemicals adhering to tephra
shards. The variability of impacts may be due to the season of eruption. These results
have implications for the volcano-climate system, peatland conservation and agriculture.
Authors
Payne, Richard JohnCollections
- Theses [3822]