NWT RESEARCH DATABASE

Regions: North Slave Region

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

Objective(s): To improve the understanding of how Canadian arctic tundra ecosystems function, and therefore how they are likely to be affected by these perturbations.

Project Description: The long-term goal of my 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. 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 and phosphorus? 2) How extensive is birch growth co-limitation by nitrogen and phosphorus across the Arctic? 3) What are the implications of nitrogen phosphorus 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 nitrogen and phosphorus additions? 5) What is the mechanistic nature of the nitrogen phosphorus 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 a 10 cm soil depth from research plots in and around Daring Lake Terrestrial Ecosystem Research Station. In all sampling, 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 the plots, small changes to the nitrogen and phosphorus levels have changed the way the plants grow. For example, in one plot researchers are trying to create realistic climate warming changes in the soil's nutrient levels. To do the, researchers 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. This experiment takes place on five 5m x 7m plots in the research valley near the Daring Lake research station. Birch leaf samples from the Daring Lake long-term fertilization plot will be collected to be included in a North American-wide collection of these leaves. Analysis on this group of leaves will be used to study birch leaves' nitrogen to phosphorus ratios 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 presentations are given as requested. Academic and plain language reports are made available and meaningful research collaborations continue that support data collection with many local collaborators. The fieldwork for this study will be conducted from May 2, 2016 to September 9, 2016.