Dynamic and Succession of Ecosystems

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1 Dynamic and Succession of Ecosystems Kristin Heinz, Anja Nitzsche Basics of Ecosystem Analysis

2 Structure Ecosystem dynamics Basics Rhythms Fundamental model Ecosystem succession Basics Energy flow Diversity Examples

3 Ecosystem dynamics Because of the open character there is a flow between different ecosystems It is a flow of Energy transformation Stocks Dynamics in populations

4 Ecosystem dynamics Biological rhythms Circardian rhythm Annual rhythm Longer annual rhythm Tides Lunar rhythm

5 Biological rhythms Circardian rhythm Production of plants Vertical drift of limnic and marine animals Roost fly of birds in winter Annual rhythm Falling down of the leaves Hibernation Bird migration Diapause

6 Ecosystem dynamics Longer annual rhythm In population dynamics Tides Along the cost side very different and complex structure of time Characteristic vertical zoning of the animals and alga

7 Ecosystem dynamics Lunar rhythm Agitation in migration by birds, tropical mammals and insects

8 Ecosystem dynamics Human made rhythms Land use activities Change of land use Emission dynamics Environmental policy Global change Continuous climate change

9 Fundamental model of ecosystem dynamics Stored Capital (Storage) 4 1 Renewal - Accessible Carbon, - Nutrients ad Energy (Miineralisation) Exploitation - r-strategy - Pioneers - Opportunists (Juvenile Stage) RAPIDLY SLOWLY Conservation - k-strategy - Climax - Consolidation (Adult Stage) Creative Destruction -Fire -Storm -Pest - Senescence ( Disturbance Incorporation) 2 3 Organization Connectedness (Holling 1986)

10 A hypothetic trajectory of the adaptive cycle Maturity / Conservation Exergy stored Renewal / Reorganization Release / Creative destruction Pioneer stage / Exploitation connectedness

11 Disturbance Stability Ability of an ecosystem to recover or to return to the original constitution after disturbance Resiliency Dimension for the ability of an ecosystem to survive a disturbance Capacity Intensity of resiliency factors which can be buffer in an ecosystem Only stable ecosystems can buffer

12 Disturbance Difference from the original ecological factors Direct and indirect damages

13 Ecosystem Succession - Definition A fundamental concept in ecology Refers to more-or-less predictable and orderly changes in the composition or structure of an ecological community Initiation by: Formation of a new, unoccupied habitat (e.g., a lava flow or a severe landslide) primary succession Some form of disturbance (e.g. fire, severe windthrow) of an existing community secondary succession

14 Ecosystem Succession - Definition The trajectory of ecological change can be influenced by: site conditions the interactions of the species present more stochastic factors such as availability of colonists or seeds

15 Ecosystem Succession - Definition Stable end-stage called climax, sometimes referred to as the 'potential vegetation' of a site, shaped primarily by the local climate Has been largely abandoned by modern ecologists in favour of nonequilibrium ideas of how ecosystems function Most natural ecosystems experience disturbance at a rate that makes a "climax" community unattainable climate change expansions and introductions

16 Ecosystem Succession - Factors Succession usually occurs in areas where no other species offer competition in the area The type of organisms' that occupy areas in such circumstances depends on a number of factors Climate Temperature, precipitation, sunlight Soil ph, composition of the soil Human Intervention pollution, acid rain

17 Ecosystem Succession Energy Flow Energy flow is fundamentally changed demonstrated in the quantity of standing crop in the ecosystem During early seral stages energy inputs > outputs Disturbance by external factors the energy loss > inputs Accumulation of energy as biomass high metabolic rates high productivity which maximises the energy flow in the system

18 Ecosystem Succession - Productivity Increases proportional to the amount of standing crop The percentage gross productivity is fixed as net productivity is not continuous with progression Early seral stages: small short-living plants dominate, have a high yield and individual plants require very little energy for maintenance r-selected life-histories Later seral stages: large long-living plants dominate which use high levels of their gross productivity for respiration to maintain their bodies k-selected life-histories

19 Ecosystem Succession - Diversity Number of species progresses rapidly as plants and animals colonise the area In later seres the rate of increase decreases Increasing interspecific competition it is the intermediate seres which contain the largest number of species present at any one time during the succession

20 Ecosystem Succession - Trophic Structure Early seres are short, linear food chains which are easily upset if one element in the food chain is removed As the succession progresses the ecosystem becomes more layered and species diversity increases creating a complex food web The more complex food webs greater stability allows alternative energy flows when one element of the food chain is disrupted

21 Ecosystem Succession - 1 st Example Primary Succession: colonisation of bare rock Pioneer community: lichens provide enough nutrients to support a community of small plants such as mosses typically replaced by ferns With erosion of rock and increasing amounts of organic material a large layer of soil is gradually built up This soil allows plants such as grasses and small flowering plants to grow followed by shrubs and trees climax community?

22 Ecosystem Succession - 2 nd Example Secondary succession: after forest fire Spores, seeds and vegetative organs may remain viable in the soil Influx of animals and plants through dispersal and migration from the surrounding area Succession does not begin with pioneer species but with species from intermediate seres