Fishing!!! (Stream ecology edition)

I went fishing in a small feeder stream to the Thornapple River. My best-guess is that the "crick" drained about 30 square miles. The water was low due to five weeks with almost no rain.

The deepest hole was 30" deep which was pretty impressive since the average depth was 6" to 8" deep.

Another thing that stood out in my mind was that the portions of the bank that were lined with Silver Maple (Acer saccharinum) were draped with curtain-walls of finely netted roots which were hanging into the water. Rapunzel's tresses, yes...that is what those roots were like.

If you are a fisherman then you appreciate all of the "structure" that can hold bait-fish and insect larvae and the like.

The opposite bank was lined with Box Elder (Acer negundo) and there were ZERO roots dragging in the water.

Trees on stream-banks are a mixed bag for fisherman. Too many and it is hard to make a cast and the dead-falls allow decent fish to wrap the line around one and break off. Too few and there is not enough "structure".

Another factor is that too much shade suppresses grasses and sod and can make erosion WORSE. Shade also reduces the amount of photosynthesis that happens within the stream. The sun is the energy-pump that drives the system.

For streams with very low flow-rates, huge dumps of tree leaves in the autumn can deplete the oxygen level as the leaves decay and fish-kill can result.

Every climate is a little bit different, but I think 75% grassland/pasture and 25% trees/brush is probably a good mix for southern Michigan. The difference between the Silver Maple and Box Elder and how their roots provided below-the-water-surface structure for aquatic life was stark. I have seen many bush-willow species that had root structure similar to the Silver Maple.

Neither Silver Maple or Box Elder are considered valuable trees although you can get a 16' saw-log out of a Silver Maple and it is almost impossible to get one out of a Box Elder. I have seen Silver Maple tapped for sap but I have never seen a Box Elder tapped. Silver Maple also splits more easily for fire wood, but both woods are light and rot rapidly. All in all, if you HAD to choose between the two, if you can grow Silver Maple, it should get the nod.

This is a topic that is under-studied. Perhaps because it seems too simple to just LOOK and catalog which species of trees create the best aquatic micro-structure with their roots.

In ecology, almost all of the interesting things happen where two or three different ecosystems come together.