Rob is doing an experiment on plant Inflorescences, the flowering parts of a plant that contain reproductive organs like the pistil and stamens.
He wants to know if warming affects seed weights. Seed weights may tell you how well a plant is going to reproduce because it may be correlated with germination rate. Germination is the number of seeds that grow into an adult plant.
We collected three catkins from each plot in the Barrow Dry Site, which contains 48 plots that each have an area of one meter squared. There are 24 control plots and 24 experimental plots with open-top chambers (OTC's) that are designed to warm the air temperature one to three degrees Celsius.
Jeremy picks a Salix rotundafolia catkin in an experimental plot on the Barrow Dry Site.
The red spiky object is the Salix rotundafolia catkin that Jeremy is picking.
I'm picking catkins from a control plot on the Barrow Dry Site. The circle in the middle of the plot is for an experiment on gas production. Steve Oberbauer, of Florida International University in Miami, Florida, is also part of ITEX. He wants to know if an increase in temperature affects photosynthesis rates and gas production. By placing a air-tight cover of the circle in the plot, he can take measurements using sensors that tell him which gasses are present.
Rob is going to dry the catkins out and then weigh them for dry weight biomass. Dry weight biomass is the mass of an organism without any water. He wants to dry the catkins to standardize the data because some catkins could weigh more simply because they have more water in their cells. Drying them out takes care of the water problem.
Salix rotundafolia (willow shrub), Carex aquatilis (water sedge), Luzula arctica (arctic woodrush), Kassiope tertragona (arctic heather) are the four species that Rob is examining. Today we focused on Salix rotundafolia. The seeds of Salix rotundafolia are encased in a catkin, an elongated inflorescence that is unisexual. Many other plants have both male and female reproductive organs on the same inflorescence; however, Salix inflorescences are either male or female. The male catkins have already come and gone; so we sampled the female catkins.
We took the three largest catkins from each plot put them in a plastic zip-lock bag for each plot and labeled them with the plot number. When we got home we them put each catkin in its own separate bag with a label because each inflorescent will burst and release cottony, dandelion-like seeds. The only way to make sure which seeds belong to each catkin is to separate them out.
Although this is a different species of Salix (Salix pulchra), it shows the female catkins a little more clearly.
Here are some catkins of Salix pulcra. It would be impossible to collect and use these catkins because they are already dispersing and it's impossible to know the original dry weight mass of the catkins.