Responses to Uv-B Exposure by Saplings of the Relict SpeciesDavidia involucrataBill are Modified by Soil Nitrogen Availability

Abstract

ABSTRACT: Climate change scenarios suggest that plants will be exposed to increasing levels of ultraviolet radiation in the future. The dove tree, Davidia involucrata Bill (Davidiaceae) is a rare and endangered tree species in China. Its distribution is predicted to become more montane as the climate warms, exposing it to higher levels of UV-B and different soil conditions. We compared the effects of glasshouse ambient (7.08 uW cm-2) and increased (13.93 uW cm-2) UV-B on survivorship, secondary metabolites indicative of radiation damage, and putative defensive responses of Davidia involucrata saplings growing under current and increased nitrogen conditions (5 and 25 g m-2 a-1 N). Mortalities were higher among plants exposed to increased UV-B, but only in soils with high supplementary nitrogen. Increases in compounds associated with defense against radiation were more frequently recorded under high supplementary nitrogen conditions. This rare and localised plant is highly sensitive to elevated UV-B when gr...