Responses of Sphagnum and Carex Peatlands to Ultraviolet-B Radiation, and a Meta-Analysis of UV-B Effects on Vascular Plants

• Main Author: Searles, Peter S.
• Format: Text
• Language: unknown
• Published: DigitalCommons@USU 2000
• Subjects: sphagnum peatlands; carex peatlands; ultraviolet-b radiation; vascular plants; Ecology and Evolutionary Biology; Environmental Sciences; Plant Sciences; Antarctic; Argentina; Austral; The Antarctic; Antarc*; Antarctica; Tierra del Fuego
• Online Access: https://digitalcommons.usu.edu/etd/6578; https://doi.org/10.26076/1d7d-a8ce; https://digitalcommons.usu.edu/context/etd/article/7633/viewcontent/2000_Searles_Peter.pdf

The severity of stratospheric ozone depletion in the temperate and polar latitudes has raised concerns about the sensitivity of terrestrial vegetation and ecosystems to solar ultraviolet (UV-B) radiation. This dissertation examined the responses of plants and microbes to solar UV-B for 3 years in Tierra del Fuego, Argentina (55° S). This region is under the influence of the Antarctic "ozone hole" during the austral spring. Additionally, a quantitative review of the UV-B literature was conducted using a set of statistical techniques known as meta-analysis. For the field studies in Tierra del Fuego, plots were established in a Sphagnum moss peatland and a Carex sedge fen during the spring of 1996. These plots received either near-ambient solar UV-B (90% of ambient) or reduced UV-B (20% of ambient) using specially designed plastic films. At the end of the first field season, no effects of the solar UV-B treatments were apparent on the growth and pigmentation of the plant species in either community. The height growth of the moss Sphagnum magellanicum was less under near-ambient solar UV-B than reduced UV-B during the second and third growing seasons. In contrast, volumetric density of the moss was greater under near-ambient UV-B. The growth of the vascular plants did not respond to the solar UV-B treatments even after 3 years although UV-B-absorbing compounds were greater under near-ambient UV-B in some species. Populations of testate amoebae (i.e., shelled amoebae) inhabiting S. magellanicum had greater numbers under near-ambient UV-B than reduced UV-B throughout the 3 years. This response may be an indirect effect of solar UV-B mediated by the direct effect of UV-B on S. magellanicum height growth. Fungi on the leaf surfaces of the tree Nothofagus antarctica appeared to be directly inhibited by solar UV-B. The quantitative literature review of plant field studies simulating stratospheric ozone depletion assessed the effects of elevated UV-B on 10 plant response variables from papers published between 1976 and ...