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Biological Soil Crusts Promote Desert Reclamation in China
Wang, X.-P., Young, M.H., Yu, Z., Li, X.-R. and Zhang, Z.-S. 2007. Long-term effects of restoration on soil hydraulic properties in revegetation-stabilized desert ecosystems. Geophysical Research Letters 34: 10.1029/2007GL031725.

What was done
Working at the Shapotou Desert Experimental Research Station of the Chinese Academy of Sciences, the authors studied temporal changes in soil and biotic properties at each of five sites that had experienced enhanced surface stabilization over periods of 0, 20, 34, 42 and 51 years -- which had been induced by inserting bunches of straw into the surface of what would otherwise have been ever-shifting sand and planting xerophytic shrubs within these stabilized areas -- by measuring (among other things) the properties of biological soil crusts or BSCs, which they describe as constituting "a critical component of desert ecosystems" and being "important contributors to soil fertility and stability."

What was learned
Wang et al. report that no BSCs were found at unaltered migrating sand dune sites, but that "the BSC layer in treatment plots developed and increased in thickness with time since dune stabilization." They also found that the sequentially increasing presence of BSCs "increased the soil microbial population, promoting the conversion of the desert environment to a steppe desert ecosystem." In addition, they observed that the presence of BSCs led to "surface soil enrichment of organic carbon" and "a decrease in soil bulk density."

What it means
Since the algae and lichens that are major components of BSCs are typically stimulated and grow ever better as the atmosphere's CO2 concentration is experimentally increased (see Deserts (Algae and Lichens) in our Subject Index), it logically follows that as the air's CO2 content continues to rise, so too will the productivity of BSCs continue to rise, hastening the encroachment of vegetation onto the world's deserts, as the CO2-induced greening of the earth continues.

Reviewed 5 March 2008