Effects of ozone on wild plants

Abstract

Although there is a great deal of concern about the effects of human activities on biodiversity, until recently there has been very little interest in the effects of ozone on the species that constitute the major part of the flora, the diverse herbaceous and shrubby species of natural and semi-natural communities. However, many wild species have been shown to be at least as sensitive to ozone as crops that show significant yield losses, so there is a pressing need for an evaluation of the risk to wild species posed by ozone. This review attempts to assess progress and highlight problems. It begins with a comment on semantics, discusses the difficulties involved in measuring relative ozone resistance and then proceeds to consider the effects of ozone on growth and resource allocation. The evidence for evolution of resistance is appraised and then the potential effects of several interactions (cutting\grazing, competition, soil water deficit and nutrition) are considered. The review ends with some remarks on observation of oxidant-induced changes in ecosystems.

Patterns of molecular genetic variation in Plantago major and P. intermedia in relation to ozone resistance

“…This suggests that natural selection for O $ resistance may have occurred, although additional factors cannot be discounted (Davison & Barnes, 1998). Furthermore, enhanced resistance to O $ was observed in two populations over a 6-yr period coinciding with a period of high O $ levels, thus demonstrating the strength of selection ; see also Whitfield et al, 1997 for demonstration of selection potential).…”

“…At present little is known about the genetics of O $ resistance, but some progress is being made in understanding the biochemistry of resistance (Reiling & Davison, 1994Davison & Barnes, 1998 ;Lyons et al, 1999). Lyons et al (1997Lyons et al ( , 1999 conclude that factors such as biochemical detoxification and repair processes must have been important in their study.…”

“…Present-day levels of O $ have been shown to be high enough to have adverse effects on the growth and survival of many plants, including crops and natural vegetation (see review by Davison & Barnes, 1998). Considerable variation exists both within and between species in their susceptibility to O $ damage (Barnes et al, 1999a,b).…”

“…There are now several reports suggesting a genetic component in the determination of O $ resistance (Whitfield et al, 1997 ;Davison & Barnes, 1998 and references therein). In a study by Whitfield et al (1997), artificial selection for O $ resistance was performed over four generations in two populations of P. major.…”

Physiological disturbances promoted by ozone in five cultivars of Phaseolus vulgaris L.

“…In the sixth experiment, a slight increase of the total biomass of Iraí cultivar seedlings (p = 0.098) was observed at exposure to approximately 147 ppb h ( Figure 4B). Although ozone and its reaction products are known to reduce photosynthesis and change the carbohydrate allocation, causing a reduced accumulation of biomass (Rennenberg et al, 1996), this generally occurs over the longer term, as suggested by Davison and Barnes (1998).…”