Saturday, September 14, 2013

The Scientific Method: Leaf litter samples

Much of my research involves collecting leaf litter samples from the field. There's a surprising amount of diversity in leaf litter, including insects, arachnids, and myriapods, all hanging out together under the detritus on the forest floor.

To collect leaf litter, all you need to do is grab a few handfuls of fallen leaves (usually including various amounts of soil, dead wood, moss, etc.) and stick it all in a plastic bag. It helps to use some kind of sifter first, to concentrate the litter and avoid filling up the bag with large sticks and leaves, but it's not critical.

After collecting the litter, transfer it to a funnel. You usually want to do this ASAP so that the critters in the litter don't get squished or eaten by the predators you've collected with the prey, but that's not always possible. Keeping the bags in a container with some ice helps to slow the invertebrates' movements and keeps the bags from overheating.

I had a few bags of leaf litter yesterday after a collecting trip, and I decided to showcase how I process the samples by tweeting a series of photos, embedded below. I have access to a room full of dedicated Berlese funnels, but they're easy to set up if you're interested in just testing out the method once.



In a few days, I can go back to check my samples and figure out what I caught. It's sort of like Christmas morning every time I sort one of the samples: I never know what to expect and it's exciting!
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2 comments:

  1. Joe LappJune 2, 2014 at 9:13 AM

    Awesome! How would you recommend that I collect spiders up to 1.5cm in body length *live*? At present, I put handfuls of litter on a beat sheet, spread it around, and hope (1) the spiders dart, (2) I notice them darting, and (3) I catch them before they escape. It's a slow process.

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    1. Derek HennenJune 4, 2014 at 12:16 AM

      Joe, probably the best way to do that would be with a litter sifter/litter condenser. They can be expensive, but could probably be made from two colanders taped together. Instead of just getting all the litter, you get the smaller stuff that falls through the grid, and it's easier to spread around and see what's moving. Essentially it's the same process as you're doing now, but might be a little easier. Not sure how to speed it up though, since usually I'm just using the Berlese funnels.

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