Previous research has shown that plant litter moisture contents are highly correlated with microbial activity on leaf litter. Because of this, I have closely studied how plant litter takes up water vapor from the surrounding air. To do this, I created small chambers out of PVC that enclose a microbalance pan with plant litter on it, that also hold a container of either water or salt solution and an ibutton. This is tricky, as I needed to control the conditions of the chamber without touching the litter on the scale.

The barebones of my vapor accumulation chambers

I have found that different species of litter will take up different amounts of water vapor and will take up water vapor at different rates. Both of which can have implications for the microbial activity on litter. I then was curious how this pattern might change over time.

The vapor accumulation chamber installed on a scale. Notice the ibutton and pan of water inside the scale, covered with clear teflon tape. 

Because I found that plant litter species have different water vapor sorption patterns, I then was curious what may cause the differences I observed. One hypothesis  I had, is that it may be possible that the wax concentrations on the leaf litter may affect how water diffuses into the litter. All plant leaves are covered with a cuticle, and imbedded in this cuticle are different amounts and types of wax. Wax on a leaf helps prevent water loss and can also protect from herbivory and scatter some harmful ultraviolet radiation. To determine the wax concentrations, I washed leaf litter with chloroform, and poured this rinsate into a bottle that I had previously weighed.

Washing the wax off of plant litter using chloroform

This research is being written up now for peer-review and will help to explain the differences we see in plant litter microbial respiration rates found in the literature, ultimately leading to a better understanding of plant litter decomposition.