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

生态系统服务是指生态系统为人类提供的服务。它们可以包括粮食生产、气候调节、水净化、养分循环和分解。目前，加拿大的监管制度并没有明确保护这些服务不受污染。在这里，我建议使用一种新技术，正电子发射断层扫描（PET），来解释矿物，植物和微生物如何对生态系统服务做出贡献。PET提供了观察土壤和可视化完整土壤生态系统中碳和氮流动的能力。我们通过向土壤或植物中添加碳和氮的正电子发射同位素，然后监测碳和氮如何在土壤中移动来做到这一点。萨斯喀彻温大学拥有世界上唯一专门为土壤/植物系统建造的PET探测器，称为BioPET。在过去的两年中，我与物理团队密切合作，开发了适用于北方土壤的剂量，成像和分析系统。我假设微生物的分散将受到土壤中植物和矿物质的影响，反过来，这种分散将影响生态系统服务的提供方式。我建议使用高北极、中北极和低北极的土壤和植物来评估我的假设，然后用一个结合了模式植物的人工土壤系统来跟进。我选择了北极地区的野外地点来代表北极地区常见的冰冻景观，即沙漠、荒地和低灌木苔原。同样，我将评估的植物是常见的北极植物；金针叶的山梨树，和土豆草，或棘豆，和模式植物，紫色草原三叶草或紫花苜蓿，是一种商业上常见的固氮剂在本土草原。人工土壤系统的设计是为了让我们看到不同的磷矿物如何影响植物-微生物的相互作用，以及这如何影响生态系统服务。现场系统和模型系统的结合将使我们能够描述土壤中的植物、矿物质和微生物如何为生态系统服务。在过去的五年里，我开发了一些模型，可以预测大空间尺度上微生物的丰度，并将这种丰度与气候变化联系起来。我将使用来自野外和模型系统的信息来更新这个模型，然后使用来自萨斯喀彻温省土壤调查和加拿大农业部的土壤档案，我将评估这个模型在整个加拿大和50年时间内预测微生物丰度和生态系统服务的能力。一旦完成，该模型将能够预测21世纪加拿大各地土壤生态系统服务的变化。

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.