Plant response to Los Angeles aqueduct construction in the Mojave desert

Construction of the 1913 Los Angeles aqueduct system had a different effect on vegetation productivity, diversity, and stability in the Mojave Desert than did construction of the 1970 aqueduct. Drastic disturbance was found to impede vegetation recovery, whereas slight disturbance sometimes enhanced vegetation. Comparisons of productivity, diversity, and stability measures for both aqueducts show apparent similarities of vegetation cover, biomass, and density. However, these similarities often vanish when one considers qualitative factors, such as proportion of long-lived species and typical cominants of undisturbed communities. Percentage composition of common long-lived perennials represents a good qualitative measure to supplement quantitative comparisons. Enhancement of vegetation along the right-of-way transects of the 1913 aqueduct shows considerable recovery, owing to the more than 65 years that have passed since construction.