March 5, 2007 1. Extra-credit trip reports 2. 2 assignments 3. MOVE BACK exam questions 4. Desert restoration, follow-up on guest speaker. Manuscript Critiques Due March 26 (see handout) Topical Proposals Due April 2, reviews April 11 (see handout).
1. Extra-credit trip reports
2. 2 assignments
3. MOVE BACK exam questions
4. Desert restoration, follow-up on guest speaker
Due March 26 (see handout)
Due April 2, reviews April 11 (see handout)
You can still email them any time beginning March 7 before spring break!
Exam 2, per your vote, will include prairie/savanna restoration, amphibian guest lecture, desert restoration guest speaker, desert restoration, Red Rock Canyon virtual tour, and questions about the March 19 lecture on landscape ecosystem perspective will be included.
It would be good to at least skim the highlights of the Beginner’s Guide to Desert Restoration, and the abstracts to the supplemental journal articles listed on the syllabus for the Desert Restoration and Landscape Ecosystem Perspective categories (not Manipulating Successional Trajectories category nor the 2 papers in the Prairie/Savanna category).
Photo courtesy of Jessica Spencer deserts)
Yellow lines = aerial surveys
1Map provided by GIS division, Lake Mead NRA
Davis, O.K., T. Minckley, T. Moutoux, T. Jull, and B. Kalin. 2002. The transformation of Sonoran Desert wetlands following the historic decrease of burning. Journal of Arid Environments 50:393-412.
The analysis of sediments from six wetlands (cienegas) in the Sonoran Desert of Arizona, U.S.A., and Sonora, Mexico, document a marked expansion of wetland taxaFparticularly woody plantsFabout 200 years ago at the beginning of the historic period, following a decrease in charcoal percentages and increased percentages of the dung fungus Sporormiella. The presence of charred seeds and fruits of wetland plants in prehistoric sediment establishes burning of the cienega itself. The charcoal decline ca. 250 years ago precedes the first occurrence of the pollen exotic plants at several sites, the change of cienega sediment from silt to peat, and the increase of percentages of the decay fungus Tetraploa. We conclude that prior to the historic period, burning was frequent enough to exclude most woody plants (Celtis, Cephalanthus, Populus, Fraxinus, Salix) from the wetlands and suppress the abundance of bulrush (Scirpus). The cienegas were probably burned seasonally as a management tool to harvest animals and promote agriculture. Prehistoric agricultural utilization of the cienegas is demonstrated by the presence of corn (Zea) and pre-Columbian weeds. This study also records postsettlement (ca. 200 years ago) change of upland vegetation; i.e. an increase in the abundance of Juniperus, Quercus, Larrea, and Prosopis pollen. Historic fire suppression may have permitted the expansion of these non-wetland woody species.
Seeding in North American deserts has been cited to be “successful” in only 1 year in 10.
Artificial desert varnish “successful” in only 1 year in 10.– restore soil color
This has been the briefest of introductions to desert restoration. However, we will continue to touch on topics important to desert restoration during the remainder of the class – soil restoration, seed banks, landscape ecosystem perspective, human dimensions, and practical constraints, as well as in Wednesday’s virtual tour of Red Rock.