The Leaf Pack Network is an initiative of Stroud™ Water Research Center. The Stroud Center seeks to advance knowledge and stewardship of freshwater systems through global research, education, and watershed restoration.

Frequently Asked Questions

Need more than quick FAQs? Watch the 30-minute Leaf Pack Network webinar!

How do I become involved with the Leaf Pack Network (LPN)?

Go to the Get Involved page to find out what you will need to get started.

If possible, it is recommended that you attend a Leaf Pack workshop. There are two reasons we encourage individuals to attend a Leaf Pack workshop.

  1. To ensure the consistent use of protocols for gathering and entering data to the LPN, thereby increasing accuracy and reliability of the LPN data. Good scientific experimental design needs to be consistent so that results can be compared, analyzed and interpreted.
  2. To receive macroinvertebrate identification training.

Contact the LPN administrator to find out when the next Leaf Pack workshop is taking place in your area or visit our events page.

Individuals outside the mid-Atlantic region are also encouraged to join LPN! We ask that you carefully follow the procedures and that you are comfortable with macroinvertebrate identification. If you are not comfortable with identifying macroinvertebrates but would like assistance in finding training in your area, please email the LPN administrator.

Can anyone enter data onto the Leaf Pack Network?

Yes, as long as procedures were properly followed to ensure consistency among Leaf Pack experiments AND that you are confident with the macroinvertebrate data you are posting. If you need assistance with macroinvertebrate identification, please email the LPN administrator.

What is the difference between a control pack and an experimental pack?

Control leaf packs contain leaves from the three dominant trees around the stream and are placed in a riffle. Any control project data set observed on the LPN has been completed this way! Control packs are scientifically important in order that data sets are capable of being compared. Control packs provide a reference for any experimental leaf packs you may investigate.

Experimental leaf packs are filled with anything or placed anywhere you think would make an interesting investigation. For example they can be filled with grass, artificial leaves, pinecones, non-native vegetation or flower petals. Experimental packs can be placed in different locations within a stream such as a pool. This is your chance to be creative! Come up with a scientific question, form a hypothesis, do the experiment, observe, analyze your results and do what the scientists do!

This is why it is important to properly name projects; either control or experimental.

When is the best time to do the Leaf Pack Experiment?

Autumn is when nature produces the most natural leaf packs. When winter rolls around people think they missed their opportunity to do the Leaf Pack Experiment. Not true! What a lot of people are unaware of is that stream life is as active in the winter as it is in the summer! Some macroinvertebrates have adapted to perform at their best in cold temperatures, as other macroinvertebrates have adapted to be most active in warmer months.

Leaf packs can be found year-round and the leaf pack experiment can be done year-round.

How long do we leave the leaf packs in the stream?

Generally, you should leave your leaf packs in the stream for 3-4 weeks. We encourage you to check on your leaf packs weekly to ensure they are still in place and note quickly they are decomposing. Every stream is different and every leaf has a different decomposition rate.

Why does the control leaf pack have to be in the riffle area of the stream?

When leaves fall naturally into a stream they are carried by the water downstream where they usually get caught on rocks. When multiple leaves get “caught” on one another they create a leaf pack. Placing the control leaf packs in the riffle also adds consistency with all the control leaf pack experiments.

How can I ensure that I will not lose my leaf packs?

It can be tricky tying leaf packs to in-stream rocks and we suggest you plan for high stream flow. Our scientists also encountered this problem when they first started using leaf packs.

If you do not have a large rock (over a foot/30cm in a least one dimension) on which to securely tie the leaf pack, the best solution is to lash the leaf bag to a construction brick (brick with holes in the center) with strong fishing line. Place the brick, with the attached leaf bag, in the stream with the long axis of the brick parallel to the direction of the water flow. Because of its weight and placement, the bricks rarely flip over, even in fairly heavy storms. If bricks with holes in the center are used, they can be “staked” through the holes into the stream bottom providing even more stability. We advise this for use in small, low-flow streams.

For images and more detailed directions, please view our 2005 Fall Newsletter.