Drought affects the competitive interactions between Fagus sylvatica seedlings and an early successional species, Rubus fruticosus: responses of growth, water status and δ¹³C composition

Abstract

Summary• Competitive interactions between European beech ( Fagus sylvatica L.) seedlings and the early successional species Rubus fruticosus , and the role of water availability, are reported and discussed in relation to management practices and climatic changes in beech ecosystems of Central Europe.• Responses of growth, water status, gas exchange and carbon isotope composition ( δ 13 C) to two competition and three irrigation treatments were examined in a factorial-design glasshouse study.• Under regular irrigation, coexistence with R. fruticosus did not significantly affect growth, water potential and gas exchange of beech seedlings. However, moderate water shortage caused a twofold reduction in beech biomass and changes in root : shoot ratios. Drought lowered transpiration rates and predawn water potentials (below the xylem embolism threshold) for F. sylvatica ; δ 13 C of leaves and fine roots increased (discrimination was reduced). By contrast, significantly lower δ 13 C of R. fruticosus foliage indicated an improved water status. Competitive interference intensified the effects of reduced irrigation.• Water availability regulates the competitive interactions between beech seedlings and R. fruticosus . Natural regeneration of beech seedlings may be inhibited by interference from a species such as R. fruticosus , especially during summer drought, as predicted by actual climate models.

Multiple environmental control of leaf area and its significance for productivity in beech saplings

“…Madsen and Larsen 1997;Fotelli et al 2001;Rose et al 2009). In the elevated temperature treatment (24°C), the productivity was reduced by 40% when exposed to 6 vol.% instead of 12 vol.% soil moisture.…”

“…Interaction with additional factors not considered in a study is a very likely explanation for opposing results obtained in many single-factor experiments on tree-environment relationships. For example, various studies obtained contrasting results on the drought response of beech saplings and associated productivity reductions and allocation shifts (Tognetti et al 1995;Löf et al 2005;Fotelli et al 2001).…”

“…Beech seedlings and saplings were studied in their response to elevated [CO 2 ] (e.g. Heath and Kerstiens 1997;Bruhn et al 2000;Kozovits et al 2005), elevated temperature (Leverenz et al 1999;Saxe and Kerstiens 2005;Overdieck et al 2007), low soil moisture (Madsen 1995;García-Plazaola and Becerril 2000;Fotelli et al 2001;Nielsen and Jørgensen 2003;Löf et al 2005) and increased N availability (Flückiger and Braun 1999;Finzi and Canham 2000;Thomas et al 2006). Most studies found significant growth responses to these factors.…”

Does tree seedling growth and survival require weeding of Himalayan balsam (Impatiens glandulifera)?

“…This assumption is supported by the reports in literature about the differing impacts of the two species on other plants. Whereas several studies illustrate the negative impact of Rubus fruticosus on tree seedlings establishment and growth (e. g. Fotelli et al 2001;Fotelli et al 2005;Harmer et al 2005), no comparable information exists for Himalayan balsam. To our knowledge, there is no evidence that this species is able to outcompete already established tree seedlings or even substantially reduce their growth so far.…”

Growth and morphology of three forest understorey species (Calluna vulgaris, Molinia caerulea and Pteridium aquilinum) according to light availability

“…Various understorey species can be cited, such as Rubus idaeus, R. fruticosus, Cytisus scoparius and Pteridium aquilinum (see e.g. Fotelli et al, 2001;Gaudio et al, 2008;Heinrichs and Schmidt, 2009). Depending on their lifespan and vigour, they can even delay the plant succession dynamics for many years when they are fully developed (Den Ouden, 2000;Prévosto et al, 2004;Royo and Carson, 2006).…”