Peter, an undergraduate student in my lab, is interested in winter ecology – a little studied field that is more or less assumed to be of limited relevance in temperate systems, at least in comparison to warmer seasons. In the winter, ecosystem and community functions slow or stop all together. For example, primary productivity halts in deciduous trees, yet likely still occurs in microorganisms, and invertebrate community interactions (i.e., predation) are simply slowed due to an overall decrease in metabolic rates. Of the multitude of processes or interactions open to investigation, Peter decided to assess decomposition dynamics of leaf litter under the snow, and address effects of snowfall on these dynamics. To do so, five blocks with three treatment plots each were marked and sampled by removing subsamples of leaf biomass from each of the three treatment plots within blocks. Within each block, snow from one treatment plot was removed and added to another, so that there was a treatment plot with ambient snowfall, snowfall removed, and snowfall added. Now, if we could only find enough freezer space…
Peter points out a potential area to set up a blockAn added- and a removed- snow cover plotChris and Peter survey the finished block
Tools of the trade
A sampling area - leaf material was removed from beneath the snow
Three subsamples cleared of leaf materialChris surveys for the next subsample to processSnow is carefully excisedAll in one shot
Sometimes, not all the snow is removed in one shot... this leads to cold hands, since only rubber gloves were used
A few more photographs of the second collection period. It was a cloudy, humid morning, and the colors turned out a bit differently than last time because I know nothing about white balance. Additionally, a whole subset of photo I took where more or less ruined by the humidity – condensation had formed on my lens and made the images fuzzy. I’ve included one of those images though.
A couple of days ago, I collected a set of decomposing plant material bundles for my diversity effects on decomposition study. Again, this sequence illustrates some of the methods used to collect the ‘decomposition bundles’ – a combination of dead macrophyte tissue from one to five species, wrapped up with a zip-tie and attached to a string. Replicates are attached to the poles shown here and below (there are five).
Briefly, I uncovered the bundles, carefully sniped them from the string, placed them on a white tray, and bagged them in Whirl-Paks. From there, there is lab processing, which I’ll hopefully have a similar post for soon…
Replicate posts
The bundle is nearly indistinquishable from the rest of the plants around it.
A tray filled with individual bundles, waiting to be bagged.
Number 2.
Clipping a bundle from the string.
Recording bundle identification numbers
A potato sack was used to carry finished samples. It nicely floats in the 1.5 m of water.
Next time, I'm going to try to get a photograph of myself, to illustrate the depth.
Here’s a big post illustrating a decomposition assay I recently set out in the wetland. I created bundles of dead, dried macrophytes in various mixtures, attached them to 3-m of nylon rope and tied the rope to posts in the wetland. I’ll be collecting a sample soon and may post another sequence.
The overall weighing set-up
Bundles of different plant mixtures were separated and stored in these mesh bags until use.
A pile of cattail waiting to be weighed.
Some bundles were placed in a bucket
Data entry
Accumulating bundles
A poor photo, but this shows the raw material - large bags of dried plant.
A few small piles of water lily, water hyacinth and Neptunia.
A tag and ziptie.Piles
Finished bundles
An array of 21 different combinations of organic matter