We sample the production of graminoid plants (sedges and grasses) and measure the impact of goose grazing in wetlands at 3 wetland sites on Bylot Island every year. At each site, 12 new exclosures (1 m x 1 m x 50 cm high) made of chicken wire are installed in late June. At the end of the growing season in mid-August, we sample plant biomass by removing 20x20 cm plots in ungrazed and grazed areas (i.e. inside and outside exclosures). All live above-ground biomass is cut, sorted out by species and weighed dry. Use of the area by geese is monitored by counting feces on 1 x 10 m transects located near each exclosure every 2 weeks during the summer. We monitor the phenology of graminoids inside exclosures by counting flower heads and recording their stage every 2 week since 2005. We monitor the long-term impact of herbivores in wetlands with 18 permanent exclosures installed in 1994. Each exclosure excludes geese over a 4 m x 4 m area enclosed with chicken wire, and also excludes lemmings over a 2 m x 2 m area of the larger exclosure enclosed with smaller mesh welded wire. Graminoids and mosses inside these long-term exclosures are sampled at 5 to 8-year intervals. From 2007 to 2009, we also sampled the production of plants (sedges, grasses and dicotyledons) and measure the impact of goose grazing in mesic communities following the same methods as in wetlands. ** Data from the IPY years 2007-2009 are available for download. If data are downloaded and used for analyses, it would greatly be appreciated that the principal investigator be informed.

Purpose: Primary production is at the base of all terrestrial food webs and is a key parameter determining the length of food chains, and the abundance of herbivores and carnivores at higher trophic levels. It is therefore an important parameter to measure at field sites where important herbivore populations are present. In terrestrial ecosystem, primary production is measured by sampling the vegetation. We are interested into two aspects of the vegetation. First, standing crop, which can be defined as the amount of live abovebiomass present at a given time (usually at the peak of the growing season). Second, annual net primary production, which is the amount of vegetation biomass that has been produced over the course of a growing season. In annual plants, standing crop and annual net primary production are often very similar but in perennial, the two can differ considerably, as the standing crop can represent the amount of live plant biomass that has accumulated over several years. In all ecosystems, production can occur both above and belowground. However, because belowground is exceedingly difficult and time consuming to measure, we will be concerned only by aboveground production (usually, green biomass).

Summary: Not Applicable