Quantifying the Effects of Herbivores and Climate Change on Arctic Tundra Carbon Cycling
The arctic tundra has been warming disproportionately faster than the global mean. Although the tundra has historically been a carbon sink, the current state of its carbon balance is highly uncertain. Large warming induced changes to tundra ecosystems complicate our ability to model tundra carbon cy...
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ftcolumbiauniv:oai:academiccommons.columbia.edu:10.7916/d8-st6n-1q29 2023-05-15T15:03:46+02:00 Quantifying the Effects of Herbivores and Climate Change on Arctic Tundra Carbon Cycling Min, Elizabeth 2021 https://doi.org/10.7916/d8-st6n-1q29 English eng https://doi.org/10.7916/d8-st6n-1q29 Environmental sciences Tundra ecology Carbon cycle (Biogeochemistry)--Environmental aspects Herbivores--Ecology Theses 2021 ftcolumbiauniv https://doi.org/10.7916/d8-st6n-1q29 2021-06-19T22:19:59Z The arctic tundra has been warming disproportionately faster than the global mean. Although the tundra has historically been a carbon sink, the current state of its carbon balance is highly uncertain. Large warming induced changes to tundra ecosystems complicate our ability to model tundra carbon cycling. In this dissertation I explore the impact of herbivores on dry heath vegetation and carbon flux, herbivore impact on dry heath tundra canopy, and lastly, the impact higher vegetation has on the conditions under which the tundra transitions from a carbon sink to a carbon source. Chapter 1 presents a study on the impact long term herbivore absence has on dry heath tundra. I measured vegetation cover, abundances of plant growth forms and carbon flux. I demonstrate the herbivore exclusion in this tundra ecosystem results in higher vegetation abundance and greater carbon uptake. Moreover, under average environmental conditions during the measurement period, I show that excluding herbivores resulted in net carbon uptake under average temperature and light conditions during the measurement period. In chapter 2 I build upon my result from chapter 1. I quantify differences in canopy structure due to herbivore exclusion and integrate this into carbon flux estimates. I show that that different herbivore assemblages have significantly different effect on carbon fluxes. Specifically, exclusion of large herbivores results in higher carbon uptake compared to exclusion of large and small herbivores. I also demonstrate that incorporating canopy structure results in significantly lower carbon uptake during morning and evening hours than carbon flux estimates based on my results from chapter 1 would suggest. In chapter 3 I quantify the conditions under which tussock tundra transitions from a carbon sink to source and how that is impacted by increasing vegetation abundance. I show that under low light, tundra with higher vegetation abundance must surpass higher temperatures to become carbon sources compared to tundra with lower vegetation abundance. However, under high light, the conditions are reversed, and tundra with higher vegetation abundance become carbon sources at lower temperatures than tundra with lower vegetation. Thesis Arctic Climate change Tundra Columbia University: Academic Commons Arctic |
institution |
Open Polar |
collection |
Columbia University: Academic Commons |
op_collection_id |
ftcolumbiauniv |
language |
English |
topic |
Environmental sciences Tundra ecology Carbon cycle (Biogeochemistry)--Environmental aspects Herbivores--Ecology |
spellingShingle |
Environmental sciences Tundra ecology Carbon cycle (Biogeochemistry)--Environmental aspects Herbivores--Ecology Min, Elizabeth Quantifying the Effects of Herbivores and Climate Change on Arctic Tundra Carbon Cycling |
topic_facet |
Environmental sciences Tundra ecology Carbon cycle (Biogeochemistry)--Environmental aspects Herbivores--Ecology |
description |
The arctic tundra has been warming disproportionately faster than the global mean. Although the tundra has historically been a carbon sink, the current state of its carbon balance is highly uncertain. Large warming induced changes to tundra ecosystems complicate our ability to model tundra carbon cycling. In this dissertation I explore the impact of herbivores on dry heath vegetation and carbon flux, herbivore impact on dry heath tundra canopy, and lastly, the impact higher vegetation has on the conditions under which the tundra transitions from a carbon sink to a carbon source. Chapter 1 presents a study on the impact long term herbivore absence has on dry heath tundra. I measured vegetation cover, abundances of plant growth forms and carbon flux. I demonstrate the herbivore exclusion in this tundra ecosystem results in higher vegetation abundance and greater carbon uptake. Moreover, under average environmental conditions during the measurement period, I show that excluding herbivores resulted in net carbon uptake under average temperature and light conditions during the measurement period. In chapter 2 I build upon my result from chapter 1. I quantify differences in canopy structure due to herbivore exclusion and integrate this into carbon flux estimates. I show that that different herbivore assemblages have significantly different effect on carbon fluxes. Specifically, exclusion of large herbivores results in higher carbon uptake compared to exclusion of large and small herbivores. I also demonstrate that incorporating canopy structure results in significantly lower carbon uptake during morning and evening hours than carbon flux estimates based on my results from chapter 1 would suggest. In chapter 3 I quantify the conditions under which tussock tundra transitions from a carbon sink to source and how that is impacted by increasing vegetation abundance. I show that under low light, tundra with higher vegetation abundance must surpass higher temperatures to become carbon sources compared to tundra with lower vegetation abundance. However, under high light, the conditions are reversed, and tundra with higher vegetation abundance become carbon sources at lower temperatures than tundra with lower vegetation. |
format |
Thesis |
author |
Min, Elizabeth |
author_facet |
Min, Elizabeth |
author_sort |
Min, Elizabeth |
title |
Quantifying the Effects of Herbivores and Climate Change on Arctic Tundra Carbon Cycling |
title_short |
Quantifying the Effects of Herbivores and Climate Change on Arctic Tundra Carbon Cycling |
title_full |
Quantifying the Effects of Herbivores and Climate Change on Arctic Tundra Carbon Cycling |
title_fullStr |
Quantifying the Effects of Herbivores and Climate Change on Arctic Tundra Carbon Cycling |
title_full_unstemmed |
Quantifying the Effects of Herbivores and Climate Change on Arctic Tundra Carbon Cycling |
title_sort |
quantifying the effects of herbivores and climate change on arctic tundra carbon cycling |
publishDate |
2021 |
url |
https://doi.org/10.7916/d8-st6n-1q29 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Climate change Tundra |
genre_facet |
Arctic Climate change Tundra |
op_relation |
https://doi.org/10.7916/d8-st6n-1q29 |
op_doi |
https://doi.org/10.7916/d8-st6n-1q29 |
_version_ |
1766335615258853376 |