Colonization, Survival and Competition of Young Trees
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Transcript of Colonization, Survival and Competition of Young Trees
Colonization, Survival and Competition of Young Trees
Introduction I
Annual plants: Life span: one growing seasonHave to germinate, grow and bloom fast to produce seeds before the end of growing season
Perennial plants:Life span: two to more yearsPlenty of resources: rapid growthFew resources: efficient and low-loss growth
Donnerstag 30. Mai 2013 2Ökologie A&T
Introduction II
Seasonal Adaptation of annual plants:Alternation of growing season and dormant season
Preparations for dormant season:Shedding the frost-sensitive partsFrost-hardening persistent partsForming buds for the following seasonStoring energy for winter and budding in spring
-> Seasonal changes are controlled by hormonal changesAbscisin acid: Supresses budding in dormant seasonGibberelin acid: Stimulates budding in growing seasonDonnerstag, 20. April 2023 3Ökologie A&T
Picture 1: Life cycle of perennial plants
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 yearRoot formation has to be sufficient for water and nutrient intakeFrost-hardy has to be persistent enough before winterBudding and formation of leaves in spring has to be ensured
Donnerstag, 20. April 2023 4Ökologie A&T
Introduction IV
Dynamics in forest gaps:Light irradiation changes due to fires, storms or cultivationSmall gaps: 5-15% light, large gaps: 20-60% lightPlants grow faster and light-requiring species colonize gapsCompetition for light and nutrients -> selection for fast growing plants
Colonisation of gaps by:Seeds capable of flightGerm buds in the soil from previous seasons
Dominance of certain species dependent on:Number of seedsRate of germinationRate of vertical growth
Donnerstag, 20. April 2023 5Ökologie A&T
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.
Donnerstag, 20. April 2023 6Departement/Institut/Gruppe
Method I
The length grow during over one year were measured in six plants
Only Beech and Ash were examined
Donnerstag 30. Mai 2013 7Ökologie A&T
Pictures:
2 Left: Fagus sylvatica
3 Right: Fraxinus excelsior
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
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Picture 4:Terminal bud of Fraxinus excelsior
Method II
Documentation: One mark per plant and year
Results I
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What type of age distribution do the pouplations have?
Total plants in gap:
Beech (blue) 59
Ash (red) 112
Results II
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Age Distribution of a Gap in 2012
2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 20020
5
10
15
20
25
30
35
Age structure of young trees in a woodland gap (March 2012)
EscheAhorn
Year of germination
Number of trees (per 4 m2)
Beech
Results III
Donnerstag 30. Mai 2013 12Ökologie A&T
Growth of Seedlings over Time
0 20 40 60 80 100 120 140 160 180 2000
5
10
15
20
25
30
35
40
45
50
R_ = 0.45
R_ = 0.6
Tree height versus shoot growth in 2012 (ash - red; beech - blue)
Height (cm)
Shoor growth in 2012
Ash
Beech
Results IV
Donnerstag 30. Mai 2013 13Ökologie A&T
Browsing:
Mean: Beech: 0.72
Ash: 1.65
Interpretation I
Donnerstag 30. Mai 2013 14Ökologie 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.
Sources
Picture 2: Fagus sylvaticahttp://flora.nhm-wien.ac.at/Seiten-Arten/Fagus-sylvatica.htm last vistited on 26.5.2013.
Picture 3: Fraxinus excelsiorhttp://www.botanik.de/bild/fraxinus-excelsior-gemeine-esche.html , last visited on 26.5.2013.
Picture 4: Terminal bud of Fraxinus excelsiorhttp://www.uni-graz.at/walter.obermayer/plants-of-styria/images/fraxinus-excelsior.html