Winter Ecology – Jan 21 . 2014. BIOL 303
This is a tutorial session in which I intend that we (together) will address the following questions.
A PDF with some supporting images and data will be circulated afterwards.
Why is it worth knowing something about winter ecology?
- Climate change
- Species range distributions
- Living in Canada there is a lot of winter
What is meant by ‘winter’?
- Considered the dormant period
- But now its seen that there is a lot of nutrient and carbon cycling going on here.
What are the stresses that winter imposes on organisms?
- the more snow there is the more insulation there is. 10” snow = 4” glass fibre wool
- this has to do with how much air is trapped in there. So as it becomes more packed the
worse it is at insulating
- vapour pressure
Base of snow pack can hold quite a lot of water vapour, warm, and through sublimation the
water can go from ice vapour.
Therefore the air filled spaces can be saturated with water vapour.
As you go up the pack of snow the ability to hold water vapour is less. This creates a gradient
and net movement of water vapour towards the top of the snow pack.
Because the water vapour is moving up we get Depth Hoar
As it moves up it condenses, so the bottom crystals are large and growing through this
process, creating space down there. This takes time
- Homeotherms need to maintain body temperature.
- Other animals need to make sure they do now form ice in their cells. The membrane
could be ruptured with formation of ice.
o So what they do is increase the solute concentration (glucose, glycerol etc.). This
lowers the freezing