Desert Ecosystem Fragility and Human Pressure

Despite their harsh appearance, desert ecosystems are ecologically fragile precisely because their extreme scarcity of water and nutrients forces organisms to grow and reproduce very slowly, meaning that recovery from disturbance takes vastly longer than in wetter, more productive biomes. Biological soil crusts, thin living layers of cyanobacteria, lichens, mosses, and fungi that bind desert soil particles together, prevent wind and water erosion, and fix atmospheric nitrogen into forms plants can use, are especially vulnerable: a single pass of a vehicle tire or a hiking boot can crush a crust that took decades to form, and controlled studies of disturbed desert soil crusts, including long-term monitoring in the Colorado Plateau region documented by researchers such as Jayne Belnap, have found that full recovery of crust cover and function can take anywhere from several decades to over a century, depending on climate and the severity of disturbance.