What mutualism is important for ecosystem dynamics in the arid southwest? why is this mutualism important? what is causing destruction of this mutualism?

Mutualism is an association between organisms of two different species in which each benefits. Mutualistic arrangements are most likely to develop between organisms with widely different living requirements. In this case; The Lichens growing on the soil, stabilizes the sand so erosion does not occur supplies nitrogen through fixation. Destruction caused by humanity.