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.
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. |
Arctic White Heather (Cassiope tetragona) Lake Hazen 2013 |