Quantifying plant-mineral-microbe ecosystem services in the Arctic using Positron Emission Tomography.

点击翻译按钮获取中文摘要

Ecosystem services are the services provided by ecosystems that humans benefit from. They can include food production, climate regulation, water purification, nutrient cycling and decomposition. Currently, the Canadian regulatory regime does not explicitly protect these services from pollution. Here I propose to use a new technology, Positron Emission Tomography (PET), to explain how minerals, plants and microorganisms all contribute towards ecosystem services. PET provides the ability to look into soil and visualize the carbon and nitrogen flows in intact soil ecosystems. We do this by adding positron-emitting isotopes of carbon and nitrogen to soil or plants, and then monitoring how the carbon and nitrogen move through the soil. The University of Saskatchewan has the world's only PET detector specifically built for soil/plant systems called the BioPET and over the last two years I've worked closely with the physics team to develop dosing, imaging and analysis systems that will work with northern soils. I hypothesize that the dispersion of microorganisms will be influenced by the plants and minerals in the soil, and in turn this dispersion will influence how ecosystem services are provided. I propose to use field soils and plants from the High, Mid and Low Arctic to evaluate my hypothesis, and then to follow this up with an artificial soil system combined with a model plant. I selected the Arctic field sites to represent cryoturbated landscapes that are common in the Arctic, i.e. deserts, barrens and low brush tundra. Similarly, the plants I will be assessing are common Arctic plants; avens or Dryas integrifolia, and locoweed, or Oxytropis arctobia, and the model plant, purple prairie clover or Dalea purpurea, is a commercially available nitrogen fixer common in native prairies. The artificial soil system is designed to allow us to look at how different phosphorus minerals influence plant-microbe interactions and how this influences ecosystem services. The combination of field and model systems will allow us to characterize how plants, minerals and microbes in soil contribute to ecosystem services. Over the past five years, I've developed models that can predict microbial abundance across large spatial scales and can link this abundance to climate change. I will use the information from the field and model systems to update this model, and then using soil archives from Saskatchewan Soil Survey and Agriculture Canada, I will evaluate the ability of this model to predict microbial abundances and ecosystem services across Canada and along a 50 year time period. Once complete, this model will be able to predict how the soil's provision of ecosystem services will change across Canada in the 21st century.