There are some other purported roles that crusts may play.There are some definite effects on seedling establishment. There were two camps on this idea for a while. There was a group that said the crust inhibits seedling establishment and then there was the group that said the crust stimulates seedling establishment. The picture that is now coming out of this is that they do both and it really depends on what seedlings we're talking about. These crusts actually turn out to be probably one of the best lines of defense against invading, exotic annual seedlings. Now there are a number of grasses that are doing this in the west. We have a lot of things that have come over from the steppes of Russia and other places and there are two really obnoxious grasses: Bromus tectorum and Schismus barbatus. Schismus is in the hot desert, Bromus is in the cooler deserts. These are obnoxious because they are very invasive, fast growing, and unpalatable to range animals. They dry out very fast. They have sharp awns that no respectable herbivore like a cow is going to eat. They also carry range fire. Many of our rangelands and arid lands are burning much more rapidly and in a much faster cycle than they ever did before, and it's because these grasses have invaded. Well, it turns out that if you have a good cryptogamic crust or microbiotic crust, it prevents these grasses from germinating. So it's very important for protecting against the invasion of exotics. But when we look at native species it turns out that the crusts provide safe sites for many of these kinds of seeds. So the plants that grew up in North American deserts that are adapted to live in crusted areas seem to benefit by having a crust.

There are also some effects on soil moisture relationships. This is again a controversial topic. We find in some areas that crusts seem to enhance infiltration into the soil, and enhance retention of water in the soil. In other areas there has been evidence that it will work just the opposite. So this is a hot area of research right now. We're trying to figure out what is the relationship between microbiotic crusts and soil moisture relations.

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