Do chronic aboveground O3 exposure and belowground pathogen stress affect growth and belowground biomass partitioning of juvenile beech trees (Fagus sylvatica L.)?

Abstract

The impact of chronic free air ozone (O 3 ) exposure and belowground pathogen stress on growth and total biomass development of young beech trees (Fagus sylvatica L.) was investigated in a lysimeter study. Plants were growing during four years under ambient or elevated atmospheric O 3 concentrations. Additionally, in the last vegetation period the root rot pathogen Phytophthora citricola was introduced to study the interaction of ozone exposure and pathogen stress in the soil-plant system. A complete harvest at the end of the experiment enabled for the first time the assessment of fine and coarse root biomass of individual trees with a high vertical resolution down to two meter depth. Plant growth was significantly reduced by elevated ozone but not affected by P. citricola. Biomass partitioning between fine and coarse roots as well as vertical root distribution were significantly affected by both factors, whereas changes in root/shoot biomass ratio were not observed.

Contrasting ozone × pathogen interaction as mediated through competition between juvenile European beech (Fagus sylvatica) and Norway spruce (Picea abies)

“…Lippert et al 1996;Winkler et al 2009) to be related to lowered photosynthetic performance as reflected by PSII operating efficiency, J max and V C,max along with delayed leaf flushing in spring (Figs. 3, 4 and 5).…”

Structure and activities of ectomycorrhizal and microbial communities in the rhizosphere of Fagus sylvatica under ozone and pathogen stress in a lysimeter study

“…Fine root biomass was twice as high (Winkler et al 2009a) and the number ectomycorrhizal tips per root length three times higher at depth 0-20 cm compared to depth 20-40 cm. Care was taken that washed fine root samples were kept at 4°C in plastic bags and processed within 1 week following sampling in order to minimise the risk that storage conditions may alter activities i.e.…”

“…At the time of planting, average stem diameters of the trees were 7.2-9.3 mm per lysimeter. Details on biomass of the lysimeter trees are given by Gayler et al (2009) andWinkler et al (2009a). The mycorrhizal status of the seedlings was not recorded at the time seedlings were planted.…”

“…At the final harvest in September 2006, the trees were 7 years old and had average stem diameters of 24.2-28.6 mm per lysimeter (for details see Gayler et al (2009) and Winkler et al (2009a)). At harvest, trees were cut at the soil surface and the entire soil column of each lysimeter was sliced by a special lysimeter soil retriever (LSR) (UGT Environmental Measurement Devices Ltd., Muencheberg, Germany) into 20 cm thick slices as described by Seyfarth and Reth (2008).…”

Experimental setup of field lysimeters for studying effects of elevated ozone and below-ground pathogen infection on a plant-soil-system of juvenile beech (Fagus sylvatica L.)

“…This refers to both, to above-ground and to below-ground biomass ). However, as shown by Winkler et al (2009) ozone had an impact on the vertical distribution of root biomass. The proportion of fine root biomass located in the uppermost 20 cm of the soil was higher under twice ambient O 3 (39±3%) than in the ambient O 3 regime (26±2%).…”