Bidirectional recovery patterns of Mojave Desert vegetation in an aqueduct pipeline corridor after 36 years: I. Perennial shrubs and grasses

Abstract

a b s t r a c tWe studied recovery of 21 perennial plant species along a severely disturbed aqueduct corridor in a Larrea tridentata-Ambrosia dumosa plant alliance in the Mojave Desert 36 years after construction. The 97-m wide corridor contained a central dirt road and buried aqueduct pipeline. We established transects at 0 m (road verge), 20 m and 40 m into the disturbance corridor, and at 100 m in undisturbed habitat (the control). Although total numbers of shrubs per transect did not vary significantly with distance from the verge, canopy cover of shrubs, species richness, and species diversity were higher in the control than at the verge and other distances. Canopy cover of common shrubs (Ericameria nauseosa, Ambrosia salsola, A. dumosa, L. tridentata, Grayia spinosa) and perennial grasses (Elymus elymoides, Poa secunda) also varied significantly by location. Discriminant analysis clearly separated the four distances based on plant composition. Patterns of recovery were bidirectional: secondary succession from the control into the disturbance corridor and inhibition from the verge in the direction of the control. Time estimated for species composition to resemble the control is dependent on location within the disturbance corridor and could be centuries at the road verge. Our findings have applications to other deserts.Published by Elsevier Ltd.

Seeding alters plant community trajectory: Impacts of seeding, grazing and trampling on semi‐arid re‐vegetation

“…Arid and semi‐arid grasslands have been particularly challenging for reclamation because they can be slow to recover vegetation naturally (Lathrop & Archbold, ), experience widely varying spatial and temporal rainfall patterns that limit vegetation establishment (Hoffman, Barr, & Cowling, ) and have soil fertility and moisture‐holding characteristics that can further arrest plant development (Bainbridge & Virginia, ). Without active reclamation, some disturbed arid and semi‐arid sites recover well while others may take centuries for post‐disturbance recovery to resemble pre‐disturbance plant communities (Abella & Newton, ; Berry, Weigand, Gowan, & Mack, ).…”

Bidirectional recovery patterns of Mojave Desert vegetation in an aqueduct pipeline corridor after 36 years: II. Annual plants

“…Our paired re-photographs, taken in 2005 and 2006 showed the process of natural recovery of the unseeded area and the associated changes in distribution of annual and perennial plants (see Fig. 2 in Berry et al, 2015). In the 2005 plot surveys, we identified 47 species of annual forbs and grasses, of which 41 were native and 6 were exotic species (Erodium cicutarium, Bromus berteroanus, Bromus rubens, Bromus tectorum, Schismus arabicus and Schismus barbatus) (Appendix B).…”

“…Three species of pioneer shrubs dominated the plots: Ericameria nauseosa, A. salsola and A. dumosa (Appendix A, see also Berry et al, 2015). The distribution patterns of the shrubs differed by distance from the road verge: E. nauseosa was the dominant species at verge sites, A. dumosa was dominant near the undisturbed vegetation, and A. salsola and E. nauseosa were rare or absent in undisturbed vegetation immediately outside the disturbance corridor.…”

“…Prior to sampling the annual vegetation, we characterized the perennial shrubs (Berry et al, 2015). Briefly, we established 14 randomly selected 20-m  1-m plots at each of the four abovedescribed distances for a total of 56 plots.…”

“…Over time, desert shrubs can develop coppice mounds or islands of fertility beneath their canopies, potentially providing a more mesic environment, nutrition, and protection from livestock for annual plants (e.g., Brown and Porembski, 2000;Bolling and Walker, 2002;Berry et al, 2015). Development of coppice mounds may contribute to more advanced seral stages and enhance recovery of annuals.…”