Thursday, 28 August 2014

Contrasting Years

Zoe Panchen

In an earlier post, I mentioned that Lake Hazen this year was much warmer and had far less snow than last year. There were other interesting differences too. On my last day at Lake Hazen last year I finally found the bright yellow Arnica (Arnica angustifolia) flowers that I had been searching for all summer. They carpeted a stream bank below McGill Mountain. Now that I had found where they grew, I was keen to monitor their flowering time. This year though, although there were plenty of plants on the bank, there were only 20 flowers, a far cry from the hundreds of flowers last year on the very same bank. I have a couple of ideas as to why this might be the case.

Bank covered in Arnica (Anica angustifolia) flowers in 2013

The same and wider view of  the bank of Arnica (Anica angustifolia)
with just 20 flowers (marked with white plant tags) in 2014
Arctic plants pre-form their flower buds the year before. This is so that they can maximise the short growing season and not waste time developing flowers at the start of the growing season. Arctic plants also tend not to flower every year. Flowering requires a lot of energy and because the growing season is so short and there are few nutrients in the Arctic soil, it can take several years to gain enough resources to produce flowers.

Arnica (Arnica angustifolia) and spider Lake Hazen 2013


The year before I started doing my phenology research at Lake Hazen (2012) was similar to many in the last decade, much warmer than in previous decades. It was likely therefore a longer growing season, enabling the Arnica to pre-form its flowers. Along comes 2013, an atypically cold year, the Arnica flowers profusely but late. So it is possible that the Arnica used all its available resources last year flowering and hence did not have enough left to preform buds for this year. The other possibility is that because 2013 was such a cold, short summer that there was not enough time for the Arnica to preform buds for 2014.

Artctic White Heather (Cassiope tetragona) bush
covered in white flowers in 2013

Arctic White Heather (Cassiope tetragona) bush
with just 3 white flowers in bottom right hand corner in 2014.
Note the large number of spent flowers and capsules from 2013.
I noticed the Arctic White Heather (Cassiope tetragona) too this year had few flowers compared to last year, particularly in a gully high up on McGill Mountain. Last year the bushes were covered in white flowers but this year each plant only had a handful of flowers if any at all. The heather relies on the insulation of snow cover to survive the harsh Arctic winters. At Lake Hazen it only grows in gullies, depressions and the lee side of hills where the snow forms drifts. An additional reason why there may have been fewer flowers this year could be the lack of a protective layer of snow killed off many of the stems with pre-formed flower buds. The gully on McGill Mountain was filled with snow last year but not this year. There did seem to be a lot of die back on the heather this year too.

Arctic White Heather (Cassiope tetragona) Lake Hazen 2013

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