1. Colonization, Survival and Competition of Young Trees

2. Introduction I Annual plants: Life span: one growing season Have to germinate, grow and bloom fast to produce seeds before the end of growing season Perennial plants: Life span: two to more years Plenty of resources: rapid growth Few resources: efficient and low-loss growth Donnerstag 30. Mai 20132Ökologie A&T

3. Introduction II Seasonal Adaptation of annual plants: Alternation of growing season and dormant season Preparations for dormant season: Shedding the frost-sensitive parts Frost-hardening persistent parts Forming buds for the following season Storing energy for winter and budding in spring -> Seasonal changes are controlled by hormonal changes Abscisin acid: Supresses budding in dormant season Gibberelin acid: Stimulates budding in growing season Montag, 9. Juni 20143Ökologie A&T Picture 1: Life cycle of perennial plants

4. Introduction III Plant growth in areas with only 1-3% light irradiation (Mittelland) depends on different factors: Carbon balance has to be positive over the year Root formation has to be sufficient for water and nutrient intake Frost-hardy has to be persistent enough before winter Budding and formation of leaves in spring has to be ensured Montag, 9. Juni 20144Ökologie A&T

5. Introduction IV Dynamics in forest gaps: Light irradiation changes due to fires, storms or cultivation Small gaps: 5-15% light, large gaps: 20-60% light Plants grow faster and light-requiring species colonize gaps Competition for light and nutrients -> selection for fast growing plants Colonisation of gaps by: Seeds capable of flight Germ buds in the soil from previous seasons Dominance of certain species dependent on: Number of seeds Rate of germination Rate of vertical growth Montag, 9. Juni 20145Ökologie A&T

6. Introduction V Most abundant trees in the Swiss Mittelland: Shady areas: Fagus sylvaticus (Rotbuche): very shade tolerant, survives with less than 5% light Cold, humid and disturbed areas (many storms, avalanches) Acer pseudoplatanus (Bergahorn) Fraxinus excelsior (Esche) Assumption: Ash and Acer colonise areas with light faster than Beech. Beech recaptures once the conditions are in its favour. Montag, 9. Juni 20146Departement/Institut/Gruppe

7. Method I The length grow during over one year were measured in six plants Only Beech and Ash were examined Donnerstag 30. Mai 20137Ökologie A&T Pictures: 2 Left: Fagus sylvatica 3 Right: Fraxinus excelsior

8. Method II Measuring length growth of one year by examining cicatrices (Narben) on terminal buds on six plants Noting if there is browsing (Verbiss) of the main shoot Determination of age of other plants Donnerstag 30. Mai 20138Ökologie A&T Picture 4: Terminal bud of Fraxinus excelsior

9. Method II Documentation: One mark per plant and year

10. Results I Donnerstag 30. Mai 201310Ökologie A&T What type of age distribution do the pouplations have? Total plants in gap: Beech (blue) 59 Ash (red) 112

11. Results II Donnerstag 30. Mai 201311Ökologie A&T Age Distribution of a Gap in 2012 Beech

12. Results III Donnerstag 30. Mai 201312Ökologie A&T Growth of Seedlings over Time Ash Beech

13. Results IV Donnerstag 30. Mai 201313Ökologie A&T Browsing: Mean: Beech: 0.72 Ash: 1.65

14. Interpretation I Donnerstag 30. Mai 201314Ökologie A&T Ash populates a newly formed gap faster due to high germination rates and faster growth, even though it is browsed more often. Beech is better adapted to sites with low light and will probably recapture the area.

15. Sources Picture 2: Fagus sylvatica http://flora.nhm-wien.ac.at/Seiten-Arten/Fagus-sylvatica.htmhttp://flora.nhm-wien.ac.at/Seiten-Arten/Fagus-sylvatica.htm last vistited on 26.5.2013. Picture 3: Fraxinus excelsior http://www.botanik.de/bild/fraxinus-excelsior-gemeine-esche.htmlhttp://www.botanik.de/bild/fraxinus-excelsior-gemeine-esche.html, last visited on 26.5.2013. Picture 4: Terminal bud of Fraxinus excelsior http://www.uni-graz.at/walter.obermayer/plants-of-styria/images/fraxinus- excelsior.html