Originally Posted by SSPey
The fisherman aren't even united on this, at least not in my neck of the woods.
This is a complex issue, so I'll share some (potentially) counterintuitive information based on the latest science around this issue. Obviously, clearcuts benefit some species and hurt others. Let's focus on fish and rivers.
The overwhelming majority of siltation problems arise from the roads punched into watersheds. Yes, roads, not the cutting, provided there are riparian buffers in place. Overland flow is very rare in forest soils, even those that have been cut. Without overland flow to carry particles, it's darn hard to get silt moving. Roads are the problem with chronic siltation. I drive on these roads to access remote fishing areas. Guilty.
Cutting certainly accelerates massive land failures. Again, often roads are to blame because of altered hydrology and perched water. Landslides are often a punctuated input of rocks and silt and debris to rivers. A massive shock, but the fish and rivers will recover.
More interesting, landslides can be a good thing! Many watersheds have bedrock channels and lack adequate spawning gravel. Landslides are nature's own gravel replenishment mechanism. Dumps in big new rock, quickly, without the slow steady bleed of silt over decades and decades as occurs with roads. But a problem arises when landslides occur w/o big trees. Trees that fall into rivers act to retain gravel. If you have a clearcut (few or no trees remaining), then a big slide, there is nothing in the river to retain the rocks that are added. They'll sluice through the river and not contribute to spawning habitat.
nature is cool, much going on, but it's dinner time! more later if needed...
Thanks, Steve, for ur input. So much there I wasn't aware of. But in this one river I fish, I recall there was this landslide complete with the trees going in as you say. Well you guessed it. The next year the trout were trying to spawn down river from the slide, something I'd never seen in that stretch before. I attributed that to the changed hydrology, but from what you say its likely the after effect of the slide was the major contributor.