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Abiotic and biotic drivers of seedling recruitment (2007-2011)

a_gesamt_2Germination and establishment are crucial processes for colonization of bare-ground areas. Young glacier moraines in front of the retreating glaciers are ideal study sites for these processes. Abiotic factors such as frost, heat, and drought should play a major role for the survival of seeds, seedlings, juvenile and adult individuals in this environment. Empirical investigations in the field are missing. Also in the growth chamber the effects of these abiotic factors have never been tested in detail on alpine plant species. Among the biotic factors interactions between the species and mycorrhization are the most important drivers for germination and establishment in the field.
A project was designed, combining population biology, stress physiology, and mycorrhiza studies in the field and in the laboratory. The study area is located at the glacier foreland of the Rotmoosferner (Obergurgl, Ötztal, Tyrol, Austria), at the moraine formed in 1971. Here, an automatic microclimate station was installed, measuring soil, soil surface and air temperatures since 2007. A multi-factorial experiment was set up at bare-ground plots to test the effects of seed addition, irrigation, and safe sites. The number of seedlings was recorded regularly during two growing seasons. In addition, mycorrhization of seedlings was studied for selected species. Frost, heat, and drought resistance of early developmental stages (i.e., seeds, seedlings, and juveniles) were investigated and compared to that of adult individuals. Frost- and heat hardening capacity of seedlings was assessed in the field and in the growth chamber.
In addition, in the growth chamber a screening of alpine species’ seeds was performed, simulating different temperatures and drought conditions. The optimum temperature and the sensitivity to drought during germination were determined.


Research Questions

  • Are germination and establishment enhanced by irrigation?
  • Are germination and establishment enhanced by providing safe sites?
  • Is seedling establishment governed by intra- and interspecific neighbours
  • Does germination depend on particle size?
  • Does mycorrhization already occur in seedlings?
  • Are there differences in the frost-, heat-, and drought resistance of seeds, seedlings, juveniles and adults
  • Do seedlings possess a frost and heat hardening capacity?
  • Which are the optimum temperatures for germination in the growth chamber?
  • How do seeds respond to drought during germination in the growth chamber?

Funding
FWF 19090-B16 [Link]

Personnel involved
Erich Schwienbacher (PhD)
Silvia Marcante (Post Doc)  
Valentin Huter (TF)  
David Bösch (Master thesis)  
Agnes Erler (TF)  
Othmar Buchner (technical advice)
Brigitta Erschbamer (project leader)
Gilbert Neuner (second project leader)

Cooperations
Ursula Peintner  
Margreth Fleisch (Master thesis)  

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