Measurements of climate data and the effect of high light and low temperature on the photosynthetic response (photosynthetic gas exchange rates and fluorescence) of mosses and lichens at Granite Harbour

The response of photosynthesis to temperature (-5°C to +25°C) and light was investigated using gas exchange and fluorescence techniques and making concurrent measurements on a lichen (Umbilicaria aprina) and a moss (Bryum argenteum) at saturating light and temperatures. Frozen specimens of U. aprina were collected from a depth of 50cm in snow to ensure the plants had not received sunlight. The specimens were exposed to full sunlight for 8-10 hour periods and their CO2 exchange and fluorescence parameters were continuously measured.

Several data loggers were deployed to gain climate information (local and microclimates) where the plants are found. Chlorophyll a fluorescence activity of selected plants was recorded for about three weeks. Fluorescence measurements are non-contact and a positive signal indicates that the photosystems of the lichen or moss are active.