Monday, 10 August 2015

Wrapping Up Field Work

My field work at Lake Hazen is now complete and I write this as we wait at Lake Hazen to fly south. Resolute is fogged in and has been for 2 days now so the charter Twin Otter plane is unable to come to pick us up. 
Over the short Arctic summer at Lake Hazen we monitored 35 plant species and over 1800 individual plants! We visited each site twice per week and recorded the number of flowers open and the number of dispersing fruits on each tagged plant. I can use this data to determine the start peak and finish of flowering and the start and end of seed dispersal of each species.

Counting purple saxifrage (Saxifraga oppositifolia)      Photographing a tagged beautiful leaved bitter cress
flowers at my highest site on McGill Mountain             (Cardamine bellidifolia) in a mossy gully, McGill Mtn
with Lake Hazen in the background.                                with Snow Goose Valley below.
Photos by Carly Casey my field assistant for the summer. 

Nodding saxifrage (Saxifraga cernua)
one of the last species to flower.
On our last two days in the field, we counted all the undispersed fruits remaining on each of the tagged plants to estimate how near to completion the plants’ reproductive cycle was. All the species we were monitoring had finished flowering except the nodding saxifrage (Saxifraga cernua) and many species had substantially completed the seed dispersal stage. The majority of species here at Lake Hazen are flowering, fruiting and dispersing their seed all within less than 2 months.
Prickly saxifrage (Saxifraga tricuspidata) with
undispersed fruit that we counted at the end of the
field season. Some plants had as many as 500 fruits.

At some of my sites I set up a volumetric soil moisture probe to record the soil moisture. My data shows that there was a steady downward trend in soil moisture through the growing season. The moisture level rose a little at the start of the season at sites where snow was still melting (sites 20, 21 and 24) and there was also a slight rise in soil moisture after we had a little rain (<5mm) on a couple of days at the end of July. The slight rise at the end of the season could also be due to the active layer of the permafrost melting. Lake Hazen is a polar desert and receives very little precipitation (<50mm/yr compared to Ottawa that gets 800mm/yr). The main source of water for plants here is from snow melt in the spring and the active layer thawing from mid-July to early-August. The few plants that grow by the rivers and in the river deltas also get some water from glacial melt.

Soil moisture generally reduced through the growing season. Soil moisture initially rose a little at sites 19, 20 and 21 as the final snow patches melted at these sites. There was also a slight rise in soil moisture at the middle and end of July due to small rain events and the active layer of the permafrost thawing.


  1. Zoe,

    Thanks for letting us know about such an interesting place. Do you think that there a substantial number of plants that do not successfully mature their fruits because the growing season is too short in many years? If a fruit does not mature by the end of the season, does it get killed by the frost, or does it have a chance of maturing the following year?

  2. In years with short growing season the fruits of many plants do not mature, this was evident when I returned in 2014 after a very cold and short season in 2013. Studies on Arctic plant seeds from the Svalbard seed bank have also shown that seed viability is very low in Arctic plants, sometime only 10% viability.
    It is possible that some fruits and seed could continue to mature the following year especially if they are protected by snow. I have even seen flowers do this on a tufted saxifrage I monitored in 2013 and 2014 where the flower bud was above ground but survived the winter and opened early in the spring of 2014.