It’s Getting Hot in Here: A look at the impact that climate change has on alpine flowers and pollinators
Idaho as a whole, and more specifically the Sawtooth region, has been experiencing an uncharacteristically warm summer. In Stanley, June saw temperatures in the mid to high 80’s when the average high is usually in the high 60’s or low 70’s. This kind of increase in temperature is following a global trend of a warming climate. If you are a lover of the Sawtooths, you may be wondering how this area is being impacted by these warm temperatures. Luckily, a review published in 2020 in the Annals of the New York Academy of Sciences, had a similar question. This paper, titled Effects of Climate Change on Alpine Plants and their Pollinators, looked at 142 different research studies and outlined the major findings specifically on the effects of climate change on alpine plants and pollinators.
Unfortunately, this paper is behind a paywall costing up to $49.00, but I do still have access to various journals through my university, so I was able to read it for free. Plus, I will admit academic research can be challenging to read, so I went ahead and did that part for you, so that all you need to do is read this much shorter blog post. Let’s go ahead and dig into some of those findings.
First up, we’ll look at changes to the distribution of mountain ecosystems. The US Forest Service defines alpine ecosystems as those occurring above the tree line of mountains, so areas on mountains above where trees are able to grow. Things like harsh temperatures, short growing seasons, and low carbon dioxide content typically limit plant growth in alpine ecosystems. According to the paper, increased temperatures due to climate change and the resulting longer growing seasons allow sub-alpine plant communities to move upward in altitude. These sub-alpine plants include trees and larger shrubs that smaller alpine plants cannot compete with. This is not good news for alpine plant communities because these alpine plants cannot move upward as there is no up for them to move into. It is essentially leading to a decline in alpine habitat range. Not only that, but the encroachment of sub-alpine species into alpine habitat may lead to new species interactions whereby sub-alpine pollinators can have access to alpine flowers and vice versa. The author of the paper is clear in stating that it is hard to say what this might lead to. It could result in increased competition between these species that never competed before as there was no overlap in their habitat. Additionally, it could lead to new adaptations in both pollinators and flowers. Speaking of flowers and pollinators, let’s talk about phenology!
Put simply, phenology is the study of natural seasonal cycles, including the time of year that flowers start blooming. These cycles are typically driven by environmental factors such as temperature, precipitation, or light. As you can imagine, climate change is causing significant change in these cycles. The paper says that the most significant phenological change in alpine areas is probably due to earlier snowmelt. If you were in the area earlier this summer, you may have noticed this when looking at the jagged peaks and saw far less snow than typical. This creates earlier growing seasons, earlier droughts, and earlier periods of animal activity. Small herbaceous plants of alpine environment are affected because they cannot grow until most of the snow has melted, so as temperatures increase earlier in the season, snow is able to melt much earlier, allowing for earlier growth and thus earlier flowering. This may not seem like a big deal, but a shift in the time that flowers bloom can impact the pollinators that are able to visit them. It can lead to an activity mismatch where pollinators aren’t yet active while flowers are blooming, which could mean that a flower might not get pollinated and pollinators do not get the food they need. This is especially true in alpine environments because as elevation increases the number of pollinators decreases, so their relationship is particularly delicate.
Alpine habitats have lots of regional variation, including precipitation, temperature, and topography. These variations all have major impacts that lead to differences in alpine environments so broadly applying these findings to somewhere like the Sawtooths may not be entirely accurate. However, alpine environments are clearly delicate in regard to the way that climate change can impact them, so it is a good idea to be knowledgeable about these changes, especially if it can inform the way that we interact and recreate in such a beautiful place like the Sawtooths!
Jacob is a naturalist for SIHA. He really likes insects, and you can often find him flipping over logs and rocks to look for critters. When he is not on the hunt for bugs, he enjoys spending his time hiking and exploring new areas.