Having shade trees is important for first order streams that support brook trout, but second order streams can have up to 50 percent grassy banks. Grassy areas that are managed and mowed every other year, supply grasshoppers and other terrestrial bugs to the water to feed fish during the summer months.
Channel width and shape (geo-morphology), channel bottom materials (cobble and stone versus sand), stream temperature and stream vegetation are all pieces of the stream ecology puzzle and all need to be in place for a quality fishery. Wetlands that are managed and have drainage access to streams supply some needed nutrients. The sun allows periphyton, algae and diatoms to grow on the cobble rock in the stream bed. Algae and diatoms feed invertebrates. Periphytons have been called the pastures of the stream. They supply food for the macrophytes; the grazing invertebrates that in turn feed the fish.
Mayfly nymphs, stoneflies and caddis all feed off the diatoms and other algae. In some cases they feed off each other. The fish feed off the invertebrates, nymphs, flies, worms and other bio-diversity of the stream bottom. Nutrients are as important as stream habitat structures.
We need to look at all the factors and accept the fact that we need to do something about improving the streams and floodplains for the benefit of the communities along the streams. Private landowners need to do the work on their land and government needs to deal with transportation infrastructures.
Roads, culverts and narrow bridges all effect stream flows, block fish passage or cause ice jamming. Wetlands and floodplains are the emergency overflow valves that collect water during storm events. When these areas are severed from the rest of the watershed by a road, the flood waters are forced downstream, increasing velocity and volume to cause damage to someone else. Over width streams lose the ability to carry sediment. They become shallow and allow anchor ice to buildup creating ice jams. There is a reason why the term FLOOD plain is used.
Rich Redman is a retired District Conservationist for the USDA Natural Resources Conservation Service and an avid outdoorsman. His column will appear regularly. He may be reached at firstname.lastname@example.org.