Daniel S. Song - Bees on the legume Astragalus mongholicus.

Daniel Song, a doctoral student at the University of Pennsylvania, writes from Hovsgol National Park, Mongolia, where he is studying how plants and pollinators form interaction networks.

Tuesday, June 21

Next time you grab a snack or sit down for a meal, take a minute to think about what you’re eating; chances are plants and insect pollinators were involved. Tomatoes, almonds, apples and coffee are just a few examples of the hundreds of foods consumed daily by people around the world that are insect-pollinated. How do pollinators behave in natural habitats? What goes into the decision to pollinate a certain flowering species? What is it about the flowers that attract pollinators? Especially in light of colony collapse disorder, it is ever more important that we study how natural plant communities maintain their pollination services.

Our field site in the Dalbay Valley is interesting in that it has, in close proximity, two drastically different areas: the valley floor and the upper slope. The two areas differ in almost every way: plants, soil moisture, air temperature and grazing pressure, to name just a few. Using this natural divide, I can compare and contrast pollination activity in two ecologically distinct areas. As for the pollinators, there is a diverse collection of insect pollinators buzzing around: butterflies, moths, hoverflies and bumblebees, among others.

Daniel S. Song - Pulsatilla multifida, flowering.

In this beautiful backdrop, I spend my summers in northern Mongolia studying floral visual cues and pollinators. My dissertation work is divided into two parts: measuring floral and pollinator traits and monitoring pollinator visitation to flowers. The traits I am looking to measure are ones that are relevant in the act of pollinating. Take, for example, two traits I am measuring: the depth of the flower (corolla tube depth) and bumblebee tongue (proboscis) length. One reason for pollinators to visit flowers is to extract energy in the form of sugary, caloric nectar. The nectar typically sits at the base of the flower, and to reach it the bumblebee has to unfurl its tongue to taste the flower’s sweet reward. If the depth of the flower is longer than the tongue of the bumblebee, it’s unlikely that the bumblebee would visit that flower to get nectar. Corolla tube depth can, in an overly simplistic case, explain why certain bumblebees visit, or do not visit, certain flowers.

What connects the floral traits and the pollinator traits to each other is the monitoring of pollinator visitation to the flowers. The observations are painstaking and tedious but provide the key to the lock. I set up several four-square-meter plots upslope and on the valley floor to monitor pollinator visitation and flower production daily. Recording pollinator visitation to the flowers allows us to link their respective traits. This allows us to see if any repeating patterns emerge, as in the example with the corolla depth and proboscis: longer-tongued bees exclusively visit deeper flower tubes.

I will spend a full 11 summer weeks at the field site to capture the beginning and end of pollination activity as well as flower production. As the climate changes, plant and animal communities may respond in unpredictable ways. Natural pollination services (involving both the flower and pollinator) need to be studied now to anticipate how one of our most precious natural commodities will be affected.