Answer: You have identified exactly what is happening to your bark mulch. It is decomposing, which is natural, and your nice wet weather is helping things along. The bark is consistently moist a few inches below the surface and that is why you see mycellium (strings of fungus) when you dig down into the bark. The way to avoid that is to rake the bark periodically, bringing the middle section to the top so the sunshine can kill off the fungus. You won't ever completely stop this natural decomposition process, but you can slow it down by raking the bark to redistribute it. I wouldn't go so far as to turn it over each year, just rake it around in the spring and again in late July. Best wishes with your new landscape!
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