Plant‐mediated effects of elevated ultraviolet‐B radiation on peat microbial communities of a subarctic mire

Abstract

Elevated ultraviolet-B (UVB) radiation has been reported to have few effects on plants but to alter the soil microbial community composition. However, the effects on soil microorganisms have to be mediated via plants, because direct radiation effects are only plausible on the uppermost millimeters of soil. Here, we assessed secondary effects of UVB on soil microbes. The responses in the dominant plant Eriophorum russeolum, peat pore water and microbial communities in the peat were recorded at a subarctic mire in the middle of the third growing season under field exposure simulating 20% depletion in the ozone layer. The UVB treatment significantly reduced the sucrose and the total soluble sugar (sucrose 1 glucose 1 fructose) concentration of the plant leaves while increasing the sucrose concentration in the belowground storage organ rhizome. The starch concentration of the leaves was also slightly reduced by elevated UVB. In the plant roots, carbohydrate concentrations remained unaffected but the total phenolics concentration increased under elevated UVB. We suggest that the simultaneously observed decrease in bacterial growth rate and the altered bacterial community composition are due to UVB-induced changes in the plant photosynthate allocation and potential changes in root exudation. There were no effects of elevated UVB on microbial biomass, peat pore water or nutrient concentrations in the peat. The observed responses are in line with the previously reported lower ecosystem dark respiration under elevated UVB, and they signify that the changed plant tissue quality and lower bacterial activity are likely to reduce decomposition.

Minor long-term effects of ultraviolet-B radiation on methane dynamics of a subarctic fen in Northern Finland

“…We have earlier reported similar stress related results when peatland microcosms with intact vegetation were exposed to elevated ozone concentration (Mörsky et al 2008). Additionally, Rinnan et al (2008) showed that elevated UV-B reduced sugar content in E. russeolum leaves and directed the carbon allocation towards rhizomes and roots. Moreover, the results of the mesocosm study with E. angustifolium under elevated UV-B radiation indicated enhanced root exudation (Rinnan et al 2006).…”

Activity, abundance and structure of ammonia-oxidizing microorganisms in plateau soils

“…low atmospheric pressure, low oxygen content in air and strong ultraviolet exposure) which might have significant impact on soil microbes and can lead to a distinctive belowground microbial community [4,10,25,26]. A few previous studies have investigated ammonia-oxidizing microorganisms in meadow, forest and farmland soils on the Tibetan Plateau (China) [34,36,47] and in grassland soils on the Inner Mongolia Plateau (China) [3], while factors regulating the distribution of AOA and AOB in alpine soils are not well understood.…”

Observed and predicted effects of climate change on Arctic caribou and reindeer

“…In addition to the effects of temperature on forage quality, rising atmospheric greenhouse gas concentrations are predicted to increase surface UV-B radiation (Taalas et al 2000) with a broad array of potential effects for organisms ). For Rangifer forage species, increases in UV-B radiation can reduce forage quality by increasing concentrations of phenolics and other secondary compounds (Soppela et al 2006;Rinnan et al 2008; see review by Turunen et al 2009), thereby reducing digestible energy and available protein (Lawler and White 2006;McArt et al 2009;Turunen et al 2009). Changes in forage quality are expected to vary regionally (Hansen et al 2006;Turunen et al 2009), and this variation will likely be significant for how well Rangifer populations are able to cope with other environmental changes due to the multiplier effects of forage quality on Rangifer condition and populations (White 1983;Cebrian et al 2008).…”