PARENT SESSION
Poster Session 9: Arid Lands and Deserts
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Successional Trends Following Cultivation in Owens Valley, California.
Naumburg, Elke*,1, Hubbard, Paula2, Martin, Dave2, McLendon, Terry3, 1 Pacifica Services Inc., Pasadena, CA2 Los Angeles Department of Water and Power, Bishop, CA3 MWH, Fort Collins, CO
ABSTRACT- Successional dynamics in arid ecosystems are less well understood than in more mesic ecosystems. Rates of secondary succession are often considered to be relatively slow. Patterns of compositional change and the roles of various controlling factors in arid successions may differ from those in ecosystems where water is not as limited. The Owens Valley of California is located in a transitional area between the Mojave and Great Basin Deserts. Numerous locations in the area were placed under irrigated cultivation between 1890 and 1920 and many of these farms were abandoned between 1920 and 1950. Most of the sites were allowed to undergo natural secondary succession following abandonment. Reference to early plat maps and aerial photographs allowed the reconstruction of a series of chronosequences in the area around Bishop. In 2004, we sampled the vegetation on a set of these chronosequences located on alluvial fans where groundwater was at least 7 m, thereby eliminating groundwater as a factor. Results from our study indicate that the total live perennial cover on most sites returns to pre-cultivation levels in 60-80 years. Assuming linear recovery rates, compositional recovery may take 90-500 years. Recovery rates were influenced by soil type, type of agriculture (fields vs. orchards), and characteristics of late-successional species themselves. Our results suggest that, at least within the period covered by our chronosequences (50-80 years), secondary succession in these arid ecosystems results in multiple recovery pathways determined by both edaphic and historic factors.
Key words: old-field succession, desert