Effects of substrate disturbance on secondary plant succession; Mojave Desert, California.

(1) The effects of substrate disturbance on perennial plant succession in the Mojave Desert were assessed at three military camps abandoned for 40 years.

(2) Soil compaction, removal of the top layer of soil, and alteration of drainage channel density caused significant changes in perennial plant cover, density, and relative species composition.

(3) Long-lived species, predominantly Larrea tridentata, were dominant in all control areas but percentage cover and density were greatly reduced in areas where substrate alterations were significant.

(4) Pioneer species such as Ambrosia dumosa and Hymenoclea salsola had percentage cover values similar to or greater than controls in most areas where substrate alterations were significant, and these species were dominant in the majority of disturbed areas.

(5) Where substrate alterations were insignificant in disturbed areas at one camp, Larrea was the dominant species as in the control.