Base de données de recherche des TNO

étiquettes: physical sciences, climate change, carbon fluxes, tundra ecosystems

Objectif(s): To increase the understanding of tundra carbon balance of terrestrial and aquatic ecosystems and predict into the future the impacts of climate warming on these systems.

Description du projet: The broad goal of this research is to increase the understanding of tundra carbon balance of terrestrial and aquatic ecosystems and predict into the future the impacts of climate warming on these systems. Since the research team are interested in all aspects of the tundra carbon balance a variety of methods are employed. These can be broken down into 4 basic categories: 1. tundra-atmosphere fluxes - the exchange of carbon gases between the tundra and atmosphere is significant component of the carbon balance and is dependent upon vegetation cover. The research team has established 4 measurement sites near Daring Lake where these fluxes are measured annually during the late-winter and over the growing (summer) season. At each site a small (3 m high) meteorological tower has been set up. Instruments are mounted on the tower that measure carbon dioxide, heat, and water vapor exchanges, in conjunction with wind speed, solar radiation, temperature and humidity, as well as instruments to monitor soil temperature and moisture. The data from these are recorded on electronic data loggers and later retrieve for computer analysis. The systems are powered by small battery banks charged with solar panel arrays. The 4 sites where these have been set up are for upland mixed tundra, sedge wetland, low shrub tundra and tall shrub tundra. Normally the research team set up the systems in April or May and they run continuously until early September. Most of the instruments are removed for the winter period, but a small array is left on the towers to measure winter meteorology, such as solar radiation, air temperature and wind and soil temperature. 2. Methane sampling - methane gas is sampled at 2 of the research sites using small (0.15 m2) chamber systems placed over a collar inserted into the soil. 10 chambers are randomly located at each site. Sampling takes place weekly, where a syringe is inserted into a tube at the top of the chamber and a gas sample drawn off, the sample is stored and returned to the university for analysis. Collars are placed at the beginning of the season and removed at the end of each season. 3. Tundra ponds - In 2013 the research team set up a program to monitor gas (carbon dioxide and methane) from 4 tundra ponds near Daring Lake. At each pond a sample float line (floating rope) is set up between the shore and the center of the pond. Instruments to sample water temperature and gas concentration are hung off this line suspended in the water. A small inflatable boat is used to access the instruments. Water samples are taken from 2 depths in the pond and stored for transport to the university for analysis. Two small sediment samples are taken from each pond and returned to the university for analysis. The research team will continue with this sampling for the life of this application. The research team do not don't anticipate any changes to the protocol. 4. Vegetation monitoring - at each of the 4 research sites the research team have established 10 permanent vegetation monitoring plots. These small (40x40 cm) plots are marked at each corner and visited weekly to measure species abundance and coverage. No vegetation is harvested in these plots. Once a season 2 additional plots are set up at each site and abundance and species measures taken then all vegetation is harvested from the plot for further analysis. During 2014 (and each year of the application) the research team will undertake the above measurements. Site set up will occur in late April or early May and sampling will take place throughout the late-winter and through the summer, ending in mid to late September. The research team work quite closely with the Daring Lake field research station manager and cooperate with them on involving local students to come to the camp and assist in the research. The research team freely provides copies of all scientific papers from the research and frequently give public talks on the research mostly in Yellowknife. The research team also participates in the Tundra Science Camp at Daring Lake and teach students about this research. The fieldwork for this study will be conducted from April 18, 2014 to October 3, 2014.