Mountain pine beetle and hydrology

Just heard on the news today - researchers have reported how the mountain pine beetle epidemic is affecting hydrology in our watersheds.

Researchers have shown that when pine trees are killed, more light reaches the ground which in turn kills mosses on the forest floor. Mosses are responsible for retaining up to 50% of moisture that falls through the forest canopy. When the mosses are gone, the excess water runs off hillsides, creating more erosion and sedimentation than previously occurred. This will have serious impacts in areas where watersheds are used for drinking water, or where fisheries values are high.

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For my own side note, when pine forests are killed off their root systems no longer act to soak up moisture from the ground. This causes water tables to rise and compounds the problem identified by the researchers. That is the benefit of harvesting these pine stands where possible - forest companies are legally required to reforest areas they have logged, so forest cover will return sooner and hydrology will gradually improve. If areas of dead pine are left on their own, a new forest can take many more years to establish, plus you have the threat of a high amount of dry forest fuels that could lead to wildfire.