Transcript Forest - ETH Z

Woodland Hönggerberg
Forest
• Different types:
– Coppice:
young, new shoots grow on old stem
– High forest:
old, selective cutting
– Mid-height forest:
old & new through rejuvenating
important habitat
Plant community (1)
• Sum of all plants living at a specific location
– Species composition
– Frequency & distribution
– Temporal dynamics
• Plantecology:
– Interaction between plants & environment
– Prediction, which plant communities to be found under
certain conditions
Plant comunity (2)
• Factors that determine the niche:
–
–
–
–
Biogeographic region of Switzerland
Altitude
Type of soil
Silviculture
• Plants as indicators (eg. Urtica dioica)
– F:
– R:
– N:
1 = dry
1 = acidic
1 = poor
…
…
…
5 = damp
5 = alkaline
5 = rich
Examination
• Distribution & frequency of plants
• Woodland Hönggerberg
Location 1
• Number of species
Year
612
13
13
Woody species
5
6
7
Herbs
1
3
2
Year
12
13
13
Woody species
42
18
32
Herbs
15
20
6
Mosses
0
0
0
• Cover in percentage
Location 2
• Number of species
Year
12
13
13
Woody species
2
3
4
Herbs
0
0
0
Year
12
13
13
Woody species
4
3
4
Herbs
0
0
0
Mosses
27
17
23
• Cover in percentage
•Note:
Most of the area is covered by mosses.
Tough selection regime: harsh wind, acidic soil, no protection
Small species richness
Location 3
• Mainly specialized plants (Lilium martagon)
• Plants that were outcompeted in their primary niche
Location 4
• Number of species
Year
10
11
13
Woody species
3
3
2
Herbs
7
6
5
Year
10
11
13
Woody species
18
8
4
Herbs
69
82
73
Mosses
0
0
0
• Cover in percentage
•Note:
Growth of nutrient indicating plants (Allium ursinum)
good supply of nutrients & water
mainly herbs
Location 5
• Mainly herbs:
–Few species with high abundance (Allium ursinum)
–Many species with low abundance
• Nutrient richness & high humidity due to creek
• Bottom of the valley gathers nutrients from slopes
Observations (1)
• Fagus sylvatica seedlings:
– In large numbers on plateaus, decreasing number on slope
and on bottom of the valley
– High competition by fast growing herbs & humidity limits
growth of seedlings
• Fraxinus excelsior:
– Highest number on slopes
– Grows preferably under humid conditions, which are given
on the slope and on the bottom
Observations (2)
• Relation between A. ursinum & M. perennis
– A. ursinum exclusively on Location 4 & 5
(nutrient richness & humidity)
– M. perennis less present in these locations but more
abundant on the slopes
Probably due to outcompetition by A. ursinum
– Growth of A. ursinum advantageous due to release of
substances that inhibit growth of other plants
Observations (3)
• Coexistance with A. ursinum
– The existance of some plants (A. podagraria, H. helix, L.
montanum, A. nemorosa) seem to correlate positively with
A. ursinum
Probably due to same/similar niche and reduced response
to inhibitory substances
negative correlation found between A. ursinum and woody
plant seedlings
Observations (4)
• Species variety differs widely even within small areas
– Different competition and microenvironments
Conclusion
• Generally a decreasing gradient of woody species from
plateau to bottom of the valley could be observed
• Generally an increasing gradient of herbs from plateau to
bottom of the valley could be observed
• Different species richness and abundance among all locations
-> main factors:
competition
environment (T, pH, nutrients, water, steepness,..)
• Some species seem to correlate positively, others negatively
• Some of the data seemed contradictionary or unreliable