The word “Ecology” was first used by Ernst Haeckel (1869): Ecology is the scientific study of the interactions between organisms
(plant / animal / fungi) and the organic and inorganic environment.
Ecology according to Krebs (1972) is: Ecology is the scientific study of the interactions that
determine the distribution and abundance or organisms. Interactions: with the environment of
the organism
Environment = all factors and phenomena outside the organism that influence it, whether
those factors be physical and chemical (abiotic) or other organisms (biotic).
Alexander von Humboldt = founding father of ecology.
Ecology can be divided by three levels:
✓ Organism (individual); How individuals are affected by (and how they affect) their biotic and abiotic environment
✓ Population; Presence and absence of particular species, with abundance, and with trends and fluctuations in their
numbers
• Attributes of individuals, and how they combine to determine characteristics of populations
• Characteristics of populations and relation of these to aspects of the environment
✓ Community; Composition and structure of communities, and pathways followed by energy, nutrients and other
chemicals (functionality)
• Consideration of component populations
• Properties (e.g. number of species, rate of biomass production) of communities and the relation with the
environment
Why is forest ecology of importance?
❑ The forest holds important group of ecosystems, distributed over the whole world (only not under extreme conditions).
❑ Forests are important because they provide many goods & services:
❑ Local-regional-global economic production (timber!)
❑ Wide array of services (e.g. local: watershed protection / global: mitigating CO2)
❑ Many people depend on forest products for livelihood
❑ Habitat of flora and fauna → biodiversity
❑ Rapid deforestation
❑ Global conventions on CBD, Kyoto, MDG, etc.
❑ Focus on sustainable use of biodiversity in developing world
❑ Relief poverty
❑ Save biodiversity
❑ Some 1 billion people rely on forests for part of their livelihoods
❑ 60% of forests is fragmented or degraded (IUCN 2007)
❑ Improved management can optimize production of goods and services delivered by forests
Forest ecology: Base for sustainable forest management
In 2015 forest covers 3999 M ha globally(30% of the
land area) (FAO 2015). 60% of forests is fragmented or
degraded.
Forests are vegetation types dominated by large,
woody, long living/ slow growing organism (trees): =>
Good management is crucial (e.g. slow recovery after
logging, harvesting). For proper management
information is needed on growth, regeneration,
canopy dynamics, competition, population dynamics,
etc.
,ORIGIN & FOREST FORMATIONS
Alfred Russel Wallace (1863): Geology teaches us that the surface of the
land and the distribution of land and water is everywhere slowly
changing. It further teaches us that the forms of life which inhabit that
surface have, during every period of which we possess any record, been
also slowly changing.’
Wallace’s line = is a faunal boundary line drawn in 1859 by the British
naturalist Alfred Russel Wallace that separates the biogeographical
realms of Asia and Wallacea, a transitional zone between Asia and
Australia. West of the line are found organisms related to Asiatic species;
to the east, a mixture of species of Asian and Australian origin is present.
“Invention” of lignin 300 Ma (Million years ago)
Evolutionary success of trees:
⚫ Growth to big stable structure
⚫ Winning struggle for light
⚫ High longevity
Trees without flowers -> Gymnosperms (e.g. conifers)
Since 100 Million years: trees with flowers -> Angiosperms:
A. Monocots (palms, grasses; narrow leaves)
B. Dicots (broadleaved trees)
At this moment (but still counting)
⚫ 50-60,000 tree species (of which 600 conifer species)
Evolutionary success of trees: size matters :
altitude
Forests along rainfall gradient:
Factors that determine the water relationships between
plants and their environment:
– Amount of annual rainfall
– Length of the dry season (most
important for moist forests
– Evaporation (wind speed and RH)
– Soil conditions (water retention capacity
(OM content), soil texture)
– Topography (run-off of water)
Effect on forest structure and phenology:
• Lower and more open canopy
• Synchronization of plant life with seasonal
rainfall
• Changing species composition
• Typical TRF features such as buttresses, cauliflory, big climbers, and epiphytes disappear
• Other life forms, e.g. Bushes, grasses, cactuses become more dominant
Forests along an altitudinal gradient
• Vegetation change: at altitudes with
frequent and persistent clouds (high
humidity, high rainfall)
• Primary Forest: forest which has never been
subject to human disturbance.
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