Population structure of Artemisia genipi in a glacier foreland of the Central Alps e. V. Club Allegra München Erich Schwienbacher & Brigitta Erschbamer Institute of Botany University of Innsbruck Contact:

Primary succession in an ecosystem Change of species composition Plant community level Introduction Population level Change of population structure – Number of individuals – Life stage spectrum

Levels of successional changes InvasionOptimumRegression Time Type AType BType C Plant community Time Stage XStage YStage Z Succession Rabotnov (1945), White (1985), Urbanska (1992) Time Population size Species 1Species 2Species 3 Population

Hypotheses Population structure changes according to the chronosequence of the successional stages (IV) Population density and life stage spectrum correlate with coverage of vegetation and coverage of bare soil, respectively (II) Middle aged Balanced(III) Old Old For early successional species: Successional stage Population density Dominating life stage (I) Young Young

Species Artemisia genipi Weber Family: Asteraceae Endemic of the Alps In the alpine & subnival belt In the glacier foreland  early successional species

ROTMOOSFERNER Tyrol, Austria m a.s.l. 46°49‘N 11°02‘E Glacier foreland Extension of the glacier in the Little Ice Age 1858

Study site

Design of the experiment Plots: n = 30 á 1 m² 2 sections of the study site: Younger section Older section 3 groups of plot surface types: Coverage of bare soil Low < 40 % Medium % High > 55 % 15 plots each 5 plots each

Design of the experiment

Single census of plots in 2001 Number of individuals per plot Life stages For each individuum: Number of inflorescences Diameter of cushion Number of rosettes

Characterisation of life stages Number of rosettes Plant size Diameter of cushion State of reproduction 1<= 0.5 cmVegetativeSeedlings/Juveniles > 0.5 cm Vegetative Generative Small ___ Vegetative Generative Medium> 6 ___ Vegetative Generative Large Life stages

Results

Comparison of Younger and Older section n = 30 Sum of all life stages p < 0.05 No. of indv. * life stage -1 * plot -1 (mean + stddev) p < 0.05 Seedlings/Juveniles p > 0.05 Small p > 0.05 Medium p > 0.05 Large Section of study site

Comparison of Younger and Older section Life stage: Small-Vegetative Small-Generative Medium-Vegetative Medium-Generative Large-Vegetative Large-Generative Not significant! Number of individuals

Comparison of surface types Life stage: Seedlings/Juveniles For all life stages Not significant! p > 0.05 < > 55 [%] Number of individuals

Cluster analysis of population census data Median-Method with Squared Euclidean Distance Seedlings Small Medium Large & Juveniles Dendrogram ‚Transient‘ ‚Sparse‘ ‚Dense‘ ‚Highly dense‘ Plots n =

Distribution of population types in the field Seedlings Small Medium Large & Juvenile Older section Younger section Plot Study site ‚Transient‘ ‚Sparse‘ ‚Dense‘ ‚Highly dense‘

Coverage of bare soil due to population types p > 0.05 ‚Transient‘‚Sparse‘‚Dense‘ ‚Highly dense‘ Invasive population types

Summary Population types – A change in the life stage spectrum following Invasion  Optimum  Regression could not be proved – Small individuals are dominant in all population types No correlation found between coverage of bare soil and population density or population structure, respectively With proceeding primary succession – Decreasing population density – Decreasing number of Small-Vegetative life stages – Decreasing number of Seedlings/Juveniles

Conclusion In a rapidly changing ecosystem such as a glacier foreland early successional species may not establish balanced population structures Long term studies are necessary to know more about the dynamics of such populations Thank you for your attention! Best thanks to the colleagues of the Univ. of Innsbruck Contact: