Fish & Water - Sounds Wild
Trees Need Salmon

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Trees need salmon

It's late fall on a salmon stream in Alaska, and the salmon run is over. There are no fish to be seen in the water, but the salmon are here - they're in the trees and the soil.

Bears often drag their catch onto stream banks or into the forest edges to eat, and once they consume the oily roe, belly, brain and skin, the rest of the carcass is available to other animals and insects. As leaching by rain and microbial activity breaks down carcasses, nitrogen, phosphorus and other nutrients become available to streamside vegetation.

One study found that trees on the banks of salmon streams grow more than three times faster than their counterparts on salmon-free rivers. Growing side by side with salmon, Sitka spruce take 86 years, rather the usual 300 years, to become 20-inches thick. In many areas, up to 70% of the nitrogen found in riparian zone foliage comes from the sea, way of salmon.

And just as trees need salmon, salmon need trees. Vegetation shades spawning streams and keeps developing eggs cool. Streamside plants house terrestrial invertebrates that fall into the water and feed growing young salmon. Leaves and needles in the water - and the organic matter trapped by woody debris - provide food and shelter for aquatic insects, which also feed young salmon. Tree roots stabilize stream banks to slow erosion and protect the clean water salmon need. Fallen trees create pools that and provide shelter for fish.

So next time you enjoy a salmon dinner, thank a tree.