Drivers of shrub growth across the tundra, treeline, and boreal ecosystems
Rapid climate change in high northern latitudes has led to the expansion of shrubs across the tundra and at treeline (often termed “shrubification”). This widespread vegetation change has important consequences for community composition, soil nutrient cycling, and the global carbon cycle. While vari...
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| Other Authors: | , , , |
| Format: | Master Thesis |
| Language: | English |
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The University of Edinburgh
2023
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| Online Access: | https://hdl.handle.net/1842/43077 https://doi.org/10.7488/era/5623 |
| Summary: | Rapid climate change in high northern latitudes has led to the expansion of shrubs across the tundra and at treeline (often termed “shrubification”). This widespread vegetation change has important consequences for community composition, soil nutrient cycling, and the global carbon cycle. While variation in shrub growth above treeline is well documented, there is far less research on how shrub growth below treeline, in boreal ecosystems, are responding to climate change. In this MPhil, I explore the drivers of shrub growth across northern ecosystems. Boreal forests are one of the largest global carbon sinks, and yet, their understory shrubs are understudied. I conducted a literature review of boreal shrubs to understand the variation and drivers of boreal shrub growth. I found that there are regional gaps in boreal shrub studies, particularly from boreal forests in Russia, China, and central Canada. Additionally, I found potentially diverging trends in the literature between boreal shrubs in North America, which appear to be increasing, and shrubs in Fennoscandia, which appear to be decreasing. My research demonstrates the need for further research monitoring shrubs across boreal ecosystems. The relationship between shrub growth and temperature, here called climate sensitivity, is highly variable. For example, the climate sensitivity of shrub growth may vary from site to site depending on the species, topography, herbivory, tree cover, or soil nutrients. Here, I use a dataset of over 100 sites and 4,000 individual shrubs to examine how climate sensitivity varies across tundra, treeline, and boreal forest ecosystems. I found that the Arctic tundra had the strongest positive relationship between temperature and shrub growth and that the boreal forest and Arctic treeline had the weakest relationship between temperature and shrub growth. My research highlights the lack of data on boreal forest shrubs and suggests that drivers of shrub growth within boreal forests may differ from those in the tundra. |
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