Tuesday, September 14, 2010

The bees and the birds.

"Let me tell ya 'bout the..."
bees and the birds?

Bees have been in the news of late, and I am not referring to either Colony Collapse Disorder or the threat to agricultural production as pollinators decline.

The news I'm referring to relates to climate change, and how bees and the plants they pollinate may get out of synch as climate change affects dates when they emerge each spring. Biologists have theorized that food webs might be disrupted by climate change, but it is very difficult to detect. (I will be writing soon about recent findings regarding migratory birds and their food sources.) In the special case of bees and the plants they pollinate, there are a lot of interacting variables besides climate change affecting pollination:

There is growing recognition that plant–pollinator interactions can be drastically influenced by anthropogenic changes to ecosystems. Climate change, habitat fragmentation, agricultural intensification, urbanization, pollution, pesticides
and species’ invasions all have the potential to affect plant–pollinator interactions directly and indirectly.

Evidence for the consequences of climate change is difficult to tease out in complex ecological systems, but it is through long-term studies in pristine environments like Rocky Mountain Biological Laboratory that we may be starting to see effects. A recent study conducted there, high in the Rocky Mountains of Colorado, got quite a bit of attention in the U.S., Canada, and the UK last week.

James Thompson, in the Department of Ecology and Evolution at the University of Toronto, has been studying glacier lilies and bumble bees at RMBL for 17 years. This pristine study site is free of the many confounding factors that affect pollination, allowing him to examine changes in bee activity and pollination success for glacier lilies over two decades.

Over that time, he found that both bee numbers and pollination of wild lily flowers have been declining. The change appears to be due, at least in part, to earlier flowering, before bumble bees have emerged from hibernation. And earlier flowering may be due to climate change:

The onset of blooming is determined by snowmelt, with the earliest years starting a month before the latest years owing to variation in winter snowpack accumulation. Fruit set is diminished or prevented entirely by killing frosts in some years.... When frosts do not limit fruit set, pollination limitation is frequent, especially in the earlier cohorts. .... This lily appears to be poorly synchronized with its pollinators. Across the years of the study, pollination limitation appears to be increasing, perhaps because the synchronization is getting worse.

Thompson is cautious in his summary of the study:
[He] admitted the evidence from the study was still weak but said the results were a warning that the phenomenon ‘might be widespread and needs more attention’.

‘It certainly suggests that people who have warned about the possible climate-change consequence of dislocated timing between interacting species have made a reasonable argument,’ he added.

While this is an alarming story, don't worry about glacier lilies. They are common and widely distributed in montane habitats in the western U.S. The bees (and the birds; that story's next) may not be in perfect synch with their flowers (or their insect food, in the case of birds) anymore, but it's not too late to prevent things from getting to the point of losing our favorite species. We still have time before the natural community diversity that exists in the Rocky Mountains is lost.

But we need to start reducing GHG emissions now. Personally, in our communities, and through our local, state, and national governments, we need to push to reduce our carbon footprints. Now is the time.

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