Above and belowground productivity of experimental grassland communities in the field during initial assembly

Activity: Talk or presentationConference PresentationsResearch

Emanuela W. A. Weidlich - Speaker

Philipp Von Gillhaussen - Speaker

Victoria Martine Temperton - Speaker

The order of arrival of different species can change the trajectory of a community as it assembles. This is known as a priority effect, where the plants that first arrive affect the further development of the system to such an extent that their impact on the system is still detectable many years after their arrival. The more we understand community assembly, the more information we will have on how to return a degraded area to a functioning ecosystem. A large scale field experiment, called Priority Effect was established in 2012 to test whether we could create priority effects by sowing high and low diversity mixtures and changing the sequence in which plant functional groups arrived in the system. We measured above and below ground productivity, soil chemistry and root productivity using the ingrowth core method. In the first year plots with legumes sown first were more productive in aboveground biomass than grasses or forbs sown first, but not more than the control sown at the same time. Belowground we found opposite patterns of productivity: legume-first plots were less productive belowground versus grasses-first as most productive. These results indicate different biomass allocation patterns to above and belowground plant parts depending on which functional group arrived first. We repeated the in-growth core method to assess root biomass and turnover in 2014 and will see whether the belowground priority effect remains or have disappeared with time. Following the development of the species and productivity in this experiment will help us to understand the mechanisms of priority effects in grassland communities in order to use this knowledge in improving grassland restoration as well ensuring a certain level of productivity. 87 Induced systemic resistance in Arabidopsis against Pseudomonas syringae pv. tomato by disease suppressive soils Two-week-old Arabidopsis thaliana ecotype Col-0 seedlings were transferred into an autoclaved sand-soil mixture amended with 10 or 20% (weight/weight) soil that is suppressive to either take-all or Rhizoctonia root rot of wheat from fields in Washington State USA. These soils contain population sizes greater than 10 5 colony forming units per gram of wheat root of 2,4-diacetylphloroglucinol or phenazine-1-carboxylic acid-producing pseudomonads, respectively. Plants were challenge-inoculated with Pseudomonas syringae pv. tomato three weeks later. Both suppressive soils induced resistance in Arabidopsis against P. syringae similar to the well-studied Pseudomonas strains WCS417r, Q2-87 (produces 2,4-diacetylphloroglucinol) and 2-79 (produces phenazine-1-carboxylic acid). Pasteurization of the suppressive soils before adding them into the sand-soil mixture eliminated 2,4-diacetylphloroglucinol and phenazine-1-carboxylic acid-producing pseudomonads from the Arabidopsis rhizosphere and significantly reduced induced systemic resistance activity. However, population sizes of total aerobic culturable bacteria were similar in the rhizosphere of plants grown in the mixes with pasteurized and raw suppressive soils. This is the first report

AB - The order of arrival of different species can change the trajectory of a community as it assembles. This is known as a priority effect, where the plants that first arrive affect the further development of the system to such an extent that their impact on the system is still detectable many years after their arrival. The more we understand community assembly, the more information we will have on how to return a degraded area to a functioning ecosystem. A large scale field experiment, called Priority Effect was established in 2012 to test whether we could create priority effects by sowing high and low diversity mixtures and changing the sequence in which plant functional groups arrived in the system. We measured above and below ground productivity, soil chemistry and root productivity using the ingrowth core method. In the first year plots with legumes sown first were more productive in aboveground biomass than grasses or forbs sown first, but not more than the control sown at the same time. Belowground we found opposite patterns of productivity: legume-first plots were less productive belowground versus grasses-first as most productive. These results indicate different biomass allocation patterns to above and belowground plant parts depending on which functional group arrived first. We repeated the in-growth core method to assess root biomass and turnover in 2014 and will see whether the belowground priority effect remains or have disappeared with time. Following the development of the species and productivity in this experiment will help us to understand the mechanisms of priority effects in grassland communities in order to use this knowledge in improving grassland restoration as well ensuring a certain level of productivity. 87 Induced systemic resistance in Arabidopsis against Pseudomonas syringae pv. tomato by disease suppressive soils Two-week-old Arabidopsis thaliana ecotype Col-0 seedlings were transferred into an autoclaved sand-soil mixture amended with 10 or 20% (weight/weight) soil that is suppressive to either take-all or Rhizoctonia root rot of wheat from fields in Washington State USA. These soils contain population sizes greater than 10 5 colony forming units per gram of wheat root of 2,4-diacetylphloroglucinol or phenazine-1-carboxylic acid-producing pseudomonads, respectively. Plants were challenge-inoculated with Pseudomonas syringae pv. tomato three weeks later. Both suppressive soils induced resistance in Arabidopsis against P. syringae similar to the well-studied Pseudomonas strains WCS417r, Q2-87 (produces 2,4-diacetylphloroglucinol) and 2-79 (produces phenazine-1-carboxylic acid). Pasteurization of the suppressive soils before adding them into the sand-soil mixture eliminated 2,4-diacetylphloroglucinol and phenazine-1-carboxylic acid-producing pseudomonads from the Arabidopsis rhizosphere and significantly reduced induced systemic resistance activity. However, population sizes of total aerobic culturable bacteria were similar in the rhizosphere of plants grown in the mixes with pasteurized and raw suppressive soils. This is the first report
21.06.201525.06.2015

Event

Rhizosphere 4 Conference - 2015: Strechting the inface of life

21.06.1525.06.15

Maastricht, Netherlands

Event: Other