by Paul Wheaton
Mark Vander Meer gives a presentation on soil science as it relates to forestry. I was presenting in another room at the same time, so Mark gave permission to Jocelyn Campbell to record this for me. Once I saw it, I thought it was so good, that I asked Mark if it was okay to put it up on YouTube.
Mark is a soil scientist who works as a wild restoration ecologist in Montana. His presentation focuses on soil restoration and is very much question driven.
He starts off by talking about the watershed death spiral, where the soil loses its ability to hold water. Mark identifies three main reasons for that to occur: Compaction, roads, and loss of soil organic matter. He explains that the problem results in streams and springs disappearing.
He then starts talking about the basic components of soil (sand, silt, and clay) and the very important water stable aggregate. This last component is formed of sand, silt and clay held together mostly by fungi. The water stable aggregate is very important because it holds its form in the presence of water and allows the soil to keep pockets of air instead of turning to pudding. These air pockets are critical to biological life.
Mark explains that gardeners are very accustomed to creating water stable aggregate by adding compost to soil. In his work he uses slashing (the wood bits and branches left over from logging) to restore the aggregate after logging operations. He then explains that spreading slashing helps to decompact the soil and to restore biological activity. In turns this helps to restore the watershed to health.
He concludes the presentation talking about road reclamation, deer pressure, and white rot vs. brown rot.