Repeat Photography, Tumamoc Hill, 1978 (image) University of Arizona Share Print E-Mail Caption This photo, taken in 1978 by stake 912 in a flat area in the western part of the Desert Laboratory grounds on Tumamoc Hill in Tucson, Ariz., shows the changes since 1958. The same species are dominant. All the species had increased their cover inside the plot. A new species, whitestem paperflower (Psilostrophe cooperi) had appeared in the plot. Good growing conditions in 1978, including good rains, fueled the increase in ground cover by both annuals and seedlings of perennial plants. Credit Photo credit: Raymond M. Turner, US Geological Survey Usage Restrictions This photo may be used only to illustrate a story about the research described in the release, Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.