Contrasting responses of naturalized alien and native plants to native soil biota and drought: biomass and mycorrhizal colonization data.

This data set contains the raw data of an experimental project in which we examined the interactive effects of drought and presence of a soil community on the competition between native and alien grassland plant species.In our greenhouse pot experiment, we first established pots with either living or sterilized soil collected from a grassland patch near the University of Konstanz. We subsequently established competition treatments by growing ten different alien and native grassland species in absence of competition, in intraspecific competition, or in interspecific competition. For the interspecific competition treatment, we only established the combinations of alien and native plant species. Initial leaf area values were estimated for each plant, by combining initial leaf number and measurements of the width and length of the longest leaf. Soil moisture was maintained at 20% (w/w) until the fifth week of the experiment, when we started a drought treatment of four subsequent weeks, by maintaining soil moisture at 10% (w/w) in half of the pots. Plants in total were grown for 50 days, after which shoots (for all pots) and roots (for plants grown in absence of competition) were harvested, dried and weighed. Based on these data, total biomass and biomass allocation (root weight ratio) were also determined for plants grown in absence of competition. The corresponding data are found in the ‘Biomass’ tab of the file “Alien_Native_Biomass_Mycorrhizal_colonization.xlsx”.As multiple plant species positively responded to the presence of a living soil community, we used root systems of plants grown in absence of competition to examine whether colonization by arbuscular mycorrhizal fungi (AMF) explained differences in plant responses sterilized and living soil. Mycorrhizal presence and absence data, based on microscopical analysis with 100 observations per root system, following root staining using an Ink-vinegar solution, are presented in the ‘Mycorrhizal_colonization’ tab of the file “Alien_Native_Biomass_Mycorrhizal_colonization.xlsx”.