Friday, August 10, 2007
Exhibit Halls 1 and 2, San Jose McEnery Convention Center
The widening of highway 86 in the western Colorado Desert damaged and removed several mesquite mounds. These mesquite dunes are biologically very important for both ecosystem structure (primarily habitat) and process (wind control, soil accumulation and nutrient cycling). In 1992 the California Department of Transportation asked me to explore techniques for recreating these valuable habitat islands to offset these highway construction related losses. The recreation of the mesquite mounds was expected to accelerate soil recovery (soil accumulation and microbial inoculation by capture of wind transported particles, nitrogen accumulation by fixation), promote re-establishment of the original surrounding vegetation, and improve habitat for local fauna.
Literature and field research led to a better understanding of these accretion dunes, but no clear answer about how it should be done. Our team considered two options: grow the trees and then bury them in sand or create a sand mound and plant it with mesquite seedlings. We selected the second approach after monitoring sand drift (minimal) across the site, and in 1995 the project was initiated in a former borrow pit. Limited irrigation was provided for year one and two, but unfortunately this project coincided with a prolonged drought that limited growth and survival. A major rain event did not occur until fall 2005. Monitoring has continued now for twelve years. Much has been learned about mesquite dunes and wind erosion control. Although most mounds now have at least one tree growing only a few have developed large trees.
Experiments over the intervening 12 years have developed better container types and irrigation systems that would make the next mesquite mound creation project faster, cheaper and more successful.
Literature and field research led to a better understanding of these accretion dunes, but no clear answer about how it should be done. Our team considered two options: grow the trees and then bury them in sand or create a sand mound and plant it with mesquite seedlings. We selected the second approach after monitoring sand drift (minimal) across the site, and in 1995 the project was initiated in a former borrow pit. Limited irrigation was provided for year one and two, but unfortunately this project coincided with a prolonged drought that limited growth and survival. A major rain event did not occur until fall 2005. Monitoring has continued now for twelve years. Much has been learned about mesquite dunes and wind erosion control. Although most mounds now have at least one tree growing only a few have developed large trees.
Experiments over the intervening 12 years have developed better container types and irrigation systems that would make the next mesquite mound creation project faster, cheaper and more successful.
