AUTHOR=Barnes Paul W. , Ryel Ronald J. , Flint Stephan D. 

TITLE=UV Screening in Native and Non-native Plant Species in the Tropical Alpine: Implications for Climate Change-Driven Migration of Species to Higher Elevations

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 8 - 2017

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01451

DOI=10.3389/fpls.2017.01451

ISSN=1664-462X

ABSTRACT=<p>Ongoing changes in Earth’s climate are shifting the elevation ranges of many plant species with non-native species often experiencing greater expansion into higher elevations than native species. These climate change-induced shifts in distributions inevitably expose plants to novel biotic and abiotic environments, including altered solar ultraviolet (UV)-B (280–315 nm) radiation regimes. Do the greater migration potentials of non-native species into higher elevations imply that they have more effective UV-protective mechanisms than native species? In this study, we surveyed leaf epidermal UV-A transmittance (T<sub>UV A</sub>) in a diversity of plant species representing different growth forms to test whether native and non-native species growing above 2800 m elevation on Mauna Kea, Hawaii differed in their UV screening capabilities. We further compared the degree to which T<sub>UV A</sub> varied along an elevation gradient in the native shrub <italic>Vaccinium reticulatum</italic> and the introduced forb <italic>Verbascum thapsus</italic> to evaluate whether these species differed in their abilities to adjust their levels of UV screening in response to elevation changes in UV-B. For plants growing in the Mauna Kea alpine/upper subalpine, we found that adaxial T<sub>UV A</sub>, measured with a UVA-PAM fluorometer, varied significantly among species but did not differ between native (mean = 6.0%; <italic>n</italic> = 8) and non-native (mean = 5.8%; <italic>n</italic> = 11) species. When data were pooled across native and non-native taxa, we also found no significant effect of growth form on T<sub>UV A</sub>, though woody plants (shrubs and trees) were represented solely by native species whereas herbaceous growth forms (grasses and forbs) were dominated by non-native species. Along an elevation gradient spanning 2600–3800 m, T<sub>UV A</sub> was variable (mean range = 6.0–11.2%) and strongly correlated with elevation and relative biologically effective UV-B in the exotic <italic>V. thapsus</italic>; however, T<sub>UV A</sub> was consistently low (3%) and did not vary with elevation in the native <italic>V. reticulatum</italic>. Results indicate that high levels of UV protection occur in both native and non-native species in this high UV-B tropical alpine environment, and that flexibility in UV screening is a mechanism employed by some, but not all species to cope with varying solar UV-B exposures along elevation gradients.</p>