Introduction: Finding Life That Creates Soil
Many things in nature are cyclical. There’s the water cycle, the rock cycle, the cycle of seasons, the cycle of a 24 hour period, and so much more. One cycle that is often overlooked is the soil cycle. The soil cycle is crucial for life on earth. Nutrients from soil are essential for producer, or plant, growth. Producers are eaten by primary consumers, or herbivores. This continues along the food chain with the next organism eating the previous one, moving up through secondary consumers, tertiary consumers, etc. until you reach an organism that is not preyed on by anything else, the apex predator. At every step on this chain, the organisms are part of the soil cycle. Whether it is providing nutrients up to the next level, dying without being eaten and becoming part of the soil more immediately, or producing waste which makes its way into the soil. However things do not just magically turn into soil, there are complex interactions between multiple organisms that help to decompose, or break down, compounds and turn them into the earth beneath our feet. Fungi, bacteria, and invertebrates are major decomposers and play a key role in the soil cycle.
We are going to investigate some decomposers, specifically the invertebrates that live in and help leaf litter to break down and slowly turn into dirt. To do that we must first build a Berlese funnel. Entomologists, or people who study insects, commonly use this tool and it can be made using just a few basic materials. There is a holding chamber for your leaf litter, with an opening and collection chamber at the bottom. When a light is placed at the top of the chamber, the invertebrates living in the leaf litter move away from the light, and eventually emerge out the bottom and into your collection chamber. Let’s get to it!
Supplies
· Plastic bag
· Scissors
· Mason jar
· Mesh wiring
· Access to old leaves
· Lamp
· Hanger
· 1 cup of water
· Small bowl
Step 1: Begin Construction of the Berlese Funnel
Cut the bottom corner of your plastic bag. The Plastic bag will act as the holding area for your leaf litter, while the hole you just cut will lead to the invertebrate collection chamber.
Step 2: Prepare a Water Catch Chamber
Pour water into a mason jar. This collects your invertebrate samples. Only 1-2 cm is required.
Step 3: Place Opening of Bag Into the Jar
Tuck the cut out opening of the plastic bag into your mason jar. Ensure the entire opening is within the jar, to prevent organisms from escaping on the seams. Fold bag back inside out and place mason jar ring onto the top of jar.
Step 4: Place Mesh
Place the mesh over the opening to your jar and secure it with the lid. Depending on how fine your mesh is, you may want to cut additional holes in it for larger organisms to get through.
Step 5: Collect Leaf Litter and Leave Overnight
Find a good place with decomposing leaf litter. Grab handfuls of leaves that are in various states of decay for best results. Fill the bag so that it is full but not overflowing.
Step 6: Apple Light to the Top of the Berlese Funnel
Secure your Berlese funnel to a coat hanger and place it somewhere it will not be disturbed or tip over during the night. Place a light so that it shines down onto the top of the funnel and leave it on overnight. The invertebrates that live in leaf litter tend to avoid light and will move away from it, into the collection chamber. Let it sit for 24 hours. MAKE SURE THAT THE LIGHT SOURCE IS NOT TOO CLOSE TO THE COLLECTION BAG. WHEN TOUCHING THE BAG IT SHOULD NOT HAVE ANY ADDED HEAT FROM THE LIGHT SOURCE. IF YOUR LIGHT IS TOO CLOSE TO THE COLLECTION BAG IT COULD CAUSE DANGEROUS OVERHEATING OF YOUR BAG AND SPECIMEN.
Step 7: Empty Collection Chamber
After allowing the organisms to migrate away from the light overnight, check to see what made it into your collection chamber. Unscrew the top and separate the chamber from the rest of the funnel.
Step 8: Identify Organisms
Finally, pour your collection chamber into a separate bowl. This makes it easier to sort through and identify any invertebrates you may have. You can expect to find all kinds of organisms like isopods, millipedes, snails, and so much more! If you need help identifying organisms, or want to dive deeper in your quest for knowledge, there are plenty of identification field guides online at your disposal. In my collection it appears I caught a single spider. However, I collected my leaf litter during a very cold weather week. Do you think that may have impacted how many organisms I found? How? What could I have changed to collect not only more organisms but different types?
Links for Identification of organisms:
