This is another controversial area. There is not agreement among those of us who study these systems. It seems that it really depends on how you define recovery. If you're looking at recovery in terms of when the green algae and cyanobacteria come back in, it's probably several years up to a few decades. That's often the way I characterize recovery. When do the green algae come back in?

Another person looking at disturbance, Jayne Belnap, is looking at ecosystem function of the crust and asking, "When does the ecosystem function recover as measured in nitrogen fixation activity?" She's come up with some evidence that indicates that it may take a couple of hundred years for the nitrogen fixation activity to recover. So, lets say a disturbance event occurs. It takes a little while for the algae to come back in. It takes a lot longer for lichens and mosses to come in; that's on the order of decades. It may be, in terms of ecosystem function, that recovery is even longer. It also depends on whether are we talking about a cool desert up in the state of Washington or a hot desert such as the Mojave or the Chuhauhaun. The climate makes a big difference in how long it takes recovery to occur. Recovery is a topic in which I've been very interested.

I tried out this talk on a college audience before coming here because I wanted to see what they thought. One of the students said afterwards, "Erosion in the desert? It doesn't rain in the desert." Well, I'm here to tell you: it rains in the desert! This is a desert and we're seeing massive sheets of water after 10 minutes of rain. So, if you remove the protective covering on this soil, the soil will get up and move. You'll notice this is not a really steep, sloped area. It is a pretty flat plain. The water is moving all over the place, and erosion will occur.

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