NWT RESEARCH DATABASE

Regions: North Slave Region

Tags: physical sciences, vegetation, climate change, environmental change, arctic ecosystems, biogeochemistry

Objective(s): To advance the understanding of how Canadian arctic tundra ecosystems function, and therefore how they are likely to be affected by perturbations Including climate change, and resource development and extraction.

Project Description: The Arctic is undoubtedly experiencing several major perturbations including climate change, and resource development and extraction (e.g. mining and pipeline construction) that are very likely to substantially affect the structure and functioning of its ecosystems. As a terrestrial ecosystem ecologist, the long-term goal of this research over the next 15-20 years is to substantially advance the understanding of how Canadian arctic tundra ecosystems function, and therefore how they are likely to be affected by these perturbations. There are three major interconnecting themes that underlie the research program: a) The biogeochemical and ecological significance of our recent discovery that mesic tundra plant growth can be co-limited by nitrogen (N) and phosphorus (P), rather than by N alone as has widely been assumed. b) The likely direct and indirect impacts of climate change on tundra shrubs that will affect the structure, functioning and distribution of low arctic terrestrial ecosystems c) The fundamental biology of plant-microbial-soil interactions that have significant functional influences on ecosystem biogeochemistry. This research will work to answer the following questions: 1. Apart from birch, which other species within the mesic tundra plant community also have their growth co-limited by nitrogen (N) and phosphorus (P)? 2. How extensive is birch growth co-limitation by N and P across the Arctic? 3. What are the implications of NP co-limitation of plant growth for predicting mesic tundra ecosystem responses to climate warming? 4. Is growth of mesic tundra plant communities enhanced by low level N and P additions? 5. What is the mechanistic nature of the NP co-limitation? 6. What is the outcome of tundra plant-soil microbial competition for climatically realistic slow and moderate increases in nutrient availability over the 5-10 year time scale? To answer these questions, researchers will harvest whole plant communities and collect soil samples up to 10 cm soil depth for research plots in and around Daring Lake Terrestrial Ecosystem Research Station. Only small samples (<1 litre) of soil will be taken. Various analyses will be done on these soil samples including enzyme analysis, microbial analysis and chemical determinations. In many of these plots, small changes to the nitrogen and phosphorus levels have changes in the soil's nutrient levels. Research have been running an experiment since 2004 where levels of nitrogen and phosphorus are changed in the soil and the growth of birch trees is tracked. The experiment takes place on 5m x 7m plots in the research valley near the Daring Lake research station. Birch leaf samples from the Daring Lake long term fertilization will be collected to be included in the North-American collection of these leaves. Analysis on this group of leaves will be used to study birch leaves' nitrogen and phosphorus ratio across the Arctic and their correlation with variation in the soil. Only small samples of leaves will be taken at each time. This research, taken as a whole, is designed to significantly improve the understanding of the biological controls and interactions that govern the functioning of the arctic terrestrial ecosystem. Results and research is communicated in a variety of ways. Researchers welcome local aboriginal students each summer to assist and learn with them during fieldwork. Community and media presentation are given as requested. The fieldwork for this study will be conducted from May 1, 2018 to September 15, 2018.