Characteristics of alpine plants and soils along an elevational gradient, Northern Selkirk Mountains, British Columbia

• Author / Creator

  Brachmann, Cole Garrett

• Rates of climate change are accelerated at higher elevations, a pattern termed elevation-dependent warming (EDW). Consequently, the impacts of climate change on community patterning and soil development may be particularly evident in alpine environments. Alpine ecotone boundaries, such as treeline and glacier margins, are generally thought to be shifting to higher elevations. Soil properties, both physico-chemical and microbial, and soil development will likely determine the rate of both treeline advance and alpine plant movement into recently-deglaciated terrain. Soil gaseous fluxes will also influence the extent of future climate change globally and are not well understood in alpine ecosystems. I documented the current state of alpine plant community composition and soil properties along an elevational gradient, the effects of soil properties on plant species establishment in recently-deglaciated terrain, and the direction, magnitude, and mechanistic drivers of methane and carbon dioxide soil gaseous fluxes in an alpine valley in the Northern Selkirk Mountains, British Columbia. Local scale plant community composition was more strongly related to local soil properties than elevation. Soil development, associated with ongoing climate change, will likely have a large effect on community composition. I found no evidence of treeline advance occurring within at least the last decade based on the age structure of sub-alpine fir across the treeline ecotone. Three out of four transplanted later-successional alpine species were able to survive and grow in recently-deglaciated terrain. Survival was either due to recently-deglaciated terrain acting as a selection factor for a subset of individuals or chance placements in appropriate microsites for graminoid species. Artemisia norvegica had a relatively high survival but reduced growth compared to control individuals indicating that establishment of this species may be a slow process. CH4 uptake was observed across all sites and was most significant for alpine and mid elevation sites. CH4 uptake was primarily driven by soil moisture (as a reverse proxy for aeration), total carbon, and soil texture. Significant methane fluxes were only found in sites with developed soils, relatively high plant cover, and good drainage which are all expected to increase with climate change forming a potential negative feedback loop. Soil CO2 emissions were highest in sites with high plant cover, high NO3- levels, and enriched δ15N. However, these sites were likely to have large uptake of CO2 via photosynthesis by vegetation potentially offsetting or reversing the CO2 emissions as suggested by the accrual of soil organic carbon in the sites with high plant coverage.Current soil properties may be limiting treeline advance and have a strong relationship with alpine vegetation communities. The relatively slow development of soil properties may also limit the movement and establishment of herbaceous alpine vegetation into recently-deglaciated terrain, however, there is a potential for some species to survive in these areas. Soil methane uptake in the alpine environment helps to offset the general trend of greenhouse gas emission globally, although uptake is lower than emissions in many other ecosystem types (e.g., boreal wetlands). Climate change effects seem to reinforce methane uptake in alpine soils and will lead to a negative feedback in these areas.

• Subjects / Keywords

  • Transplant
  • Soil fluxes
  • Recently-deglaciated terrain
  • Environmental gradient
  • Treeline
  • Alpine
  • Alpine ecology

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-69d2-zd51

• License

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