Raymond L. Lindeman (1915-1942)

Energy and nutrient cyclesLindeman’s theory of energetic ecologic was th

main trigger to initiate the international biological program (IBP) that run from 1964 to 1974

(European projects ended in the 80s). Heinz Ellenberg (1913-1997)

Marine NPP Terrestrial NPPTropical and subtropical oceans 13Tropical rainforests 17.8Temperate oceans 16.3Broadleaf deciduous forests 1.5Polar oceans 6.4Boreal evergreen forests 3.1Coastal shelfs 10.7Mixed forsts 3.1Coral reefs 1.2Savannahs 18.8

Grasslands 2.4Shrub steppes 1Tundras 0.8Deserts 0.5Plantations 8

Total 48.3Total 56.4

Some definitions:Biomass is the mass of organisms per unit of area. It is the standing crop.Units: J×m-2 or kg×m-2

The primary productivity is the amount of energy produced per unit area by plants.Net primary productivity is the difference between gross primary productivity (GPP) and autothrophic plant respiration (AR). Gross primary productivity (GPP )is the total fixation of energy by photosynthesis per unit of area.NPP=GPP-AR; Units: J×m-2×year-1 or kg C×m-2×year-1Net primary productivity (unit= 1015 kg×year-1)

Modified from Geider et al. 2001, Gl Change Biol, 7 Biome GPPTropical rainforests 3-3.5Broadleaf deciduous forests 1.1-1.5Boreal evergreen forests 0.7-1.7Mixed forsts 0.9-1.9

Variability in gross primary productivity (unit= 1012 kg C×year-1)

Modified from Falge et al. 2002, Agr Forest Meteo, 13

Sun radiation

reflected radiation Heat energy

Tidal energy

Geothermal energy

Fossilized energy

Plants AnimalsBacteria Humans

Wind

Atmosperic water

100

34 23

42

1

0.023

0.018

0.002

0.006

0.006

23

Only 0.023% (4 1013 Watt) of the incoming radiation of the sun is converted in organic matter

100% = 1.7 1017 Watt

The earth energy budget

Fungi

Atmosphere

BiospherePedosphere

Litosphere

Ground waterHydrosphereO2

O2

O2O2

O3

O

H2OH2OH

OHO

O2

UV

CO

O2+2CO→2CO2

O2+4FeO→2Fe2O3Bleaching

Vulcanism

Water cycle

The global oxygen cycles

Photo-synthesisRespiration

The major oxygen producers are marine algae and terrestrial green plants.The major processes that reduce atmospheric oxygen are CO and iron oxidation.

Oxydation

Local and global flux of matter in the biosphere

Global cycles of main elements:C, N, O, H

Consumers

Plants

Litter Decom-posers

Soil

Local cycles of P and of trace elements:K, Ca, Mg, Cu, Zn, B, Cl, Mo, Mn, Fe

Consumers

Plants

Litter Decom-posers

Soil

BacteriaAtmos-phere

100%

The energy budget of the biosphere

17%

83%

40%

1-3%

57%

3% 57%

Net production P is calculated from

3.7: average carbon fixation rate of chlorophyllR: relative photosynthesis rate,k: extinction coefficient × m-1 (1 in terrestrial systems)C: amount of chlorophyll × m-3

Amount of radiation that reaches the biosphere

Global average energy budget

On average about 10% of energy is transmitted from one trophic levels to

the next. The marine potential productivity depends on latitude and season.

NPP increases with standing crop Modified from Whittaker, 1975, Ecol. Monogr, 23.

Photosynthetic effeciency differs betwen habitat types Modified from Webb et al., 1983, Ecology, 64.

Photosynthetic effciciency in the Argentine pampas is limited by water and temperature.

Modified from Jobbagy et al. 2002, Ecology, 83

The rate of energy transferred to the next trophic level depends on habitat type and NPP.Modified from Cebrian 1999, Am Nat, 154.

𝐶𝐸=100×𝐼𝑛𝑃𝑛−1

𝐴𝑆=100×𝐴𝑛

𝐼𝑛𝑃𝐸=100×

𝑃𝑛

𝐴𝑛𝑇𝐸=100×

𝑃𝑛

𝑃𝑛−1

Consumption efficiency Transfer efficiency Assimilation efficiency Production efficiency

P: Production at trophic level n I: Consumption at trophic level n P: Assimilation at trophic level n

The global cycle of potentially biologically active carbon

Reactive sediments >6,000Fossil carbon >5,000

Atmosphere 720 × 1012 kg

Ocean surface 700

93 90.2

Deep ocean 1,0002.8

Soil carbon 2,300

Plant and fungal biomass 600

Photosynthesis123

Plant respiration50

Microbial respiration60

Human emissions 7.7Land use 1.5

Deposition 13

Atmospheric increase = Emissions from fossil fuels + Net emissions from

changes in land use - Oceanic uptake -Residual carbon

sink

4.1 ± 0.04 = 7.7 ± 0.4 + 1.5 ± 0.7 - 2.3 ± 0.4 - 2.8 ± 0.9

Average Annual Carbon Fluxes for the period 2000-2008 (Modified from LeQuéré et al., 2009) 

Th annual increase of athmospheric carbon from fossil fuel burning

The Nitrogen cycles

RainN2

Nitrogen fixation

Phytoplankton

Marine food web

NH4OH

NH4OH

NitrificationNO3-

NO3-

Denitrification

N2

N recycling

Euphotic zone

Dark zone

Atmosphere

N recycling

The marine nitrogen cycle The soil nitrogen cycle

AtmosphereRain

N2

Soil

symbiontic Rhizobium

Decomposeranerobic Bacteria,

Fungi

NH4OHfree living Azotobacter

NH4OH

NitrificationNitrosomonas

NO2-

NO3-

Denitri-fication

Ammoni-fication Nitro-

bacter

Clostri-dium;Pseudo-monas

N2

Leaching into ocean

water

The succession of nutrient uptake can be traced by radioactive markers

32P uptake in freshwater systems

Nutrient uptake by microorganisms takes a few hours. Plants and algae need up to a day and animals a few days for maximum uptake.

The local flux of energy and matter

An ecosystem is a spatially restricted community of living and organisms (plants, animals, and microbes) that interact with

the abiotic components of their environment

ecosystem = biocoenosis + habitat Arthur George Tansley (1871-1955)

Examples of ecosystems:

Lakes Forests GrasslandsMangroves Tundras ShrublandsCoral reef Geothermal vents Deserts

Habitats that are not ecosystems in a strict sens:

Rivers Oceans Agricultures

A community is a group of species that potentially interactAn assembly is any association of species within a given area

There is still a dispute whether ‚ecosystems’ are ‚systems’ in a strict sense.

Ecosystems are characterized by a flux of energy and a circulation of inorganic matter.

Herbivores

Carnivores

Parasites

Saprovores

Mineralisers

Consumers

Reducers

Plants

Algae

Producers

Dead organic matter

Microvores

Consumers

Herbivores

Minerals

O2, CO2, H20 Light O2, CO2, H20

Mineral sink

A simple scheme of an ecosystem

Regulated or not regulated?

𝑑𝐷𝑑𝑡 =𝑐𝐾−𝑎𝑃 𝑑𝐾

𝑑𝑡 =𝑏𝑃𝐾 −𝑐𝐾 𝑑𝑃𝑑𝑡 =𝑎𝑃−𝑏𝑃𝐾 𝑑𝐷

𝑑𝑡 +𝑑𝑃𝑑𝑡 +

𝑑𝐾𝑑𝑡 =𝑐𝑜𝑛𝑠𝑡

Modelling ecosystem processes

D, P, and K are the amounts of a resource at the levels of reducers (D), producers (P) and consumers (K), respectively. Then it holds

The flux of matter through the ecosystem is predicted

to be a steady state process

Simple ecological models predict ecosystems to be self-regulated entities.

Two types of regulation

Self controlled systemStatistical averaging

Control loop

Early ecological theory saw ecosystems as self regulated entities.Examples: Predator – prey relationshipsDegree of herbivoryEnergy fluxPopulation densitiesProductivityBiodiversity

The variance – mean relationship of most populations follows Taylors power law

The majority of species has 1.5 < z < 2.5

Z = <<2 is required for population regulation

Most populations, in particular invertebrate populations are not regulated!

They are not in equilibrium

𝜎 2(𝑁 )∝𝑁 𝑧

Statistical averaging as a stabilizing force

The Portfolio effect

The average of many random variables has a lower variance than each single variable: statistical averaging

Number of variables

Varia

nce Stability𝝈𝟐∝ 𝟏

√𝑵

Aggregate ecological variables (biomass, species richness, productivity, populations) become more stable with increasing number of independent variables.

For instance, total biomass and ecosystem productivity are more stable in species rich communities.

The soil system as an example of an ecological system

From Begon, Townsend, Harper, 006. Ecology, Blackwell

Earthworms

Microfauna

Darwin on earthworms

The soil system

Soil organisms: Edaphon

Domain Kingdom Phylum Class/Order Examples Ecological function

Prokaryote Bacteria Proteobacteria Nitrosomonas, Nitrobacter, Rhizobium, Azotobacter N cycle

Prokaryote Bacteria Firmicutes Clostridium N cycle

Eukaryote Fungi Ascomycota Penicillium, Aspergillus, Fusarium, Trichoderma Saprovores

Eukaryote Chromalveolata Diatomea Primary producersEukaryote Chromalveolata Xanthophyceae Primary producersEukaryote Chromalveolata Ciliophora MicrovoreEukaryote Amoebozoa Amoeba MicrovoreEukaryote Plantae Chlorophyta Primary producersEukaryote Animalia Nematoda BacteriovoresEukaryote Animalia Rotifer SaprovoresEukaryote Animalia Tardigrada BacteriovoresEukaryote Animalia Arthropoda Collembola Fungivores

Eukaryote Animalia Arthropoda Arachnida Acarina Saprovores, Carnivores

Eukaryote Animalia Arthropoda Arachnida Pseudoscorpionida CarnivoresEukaryote Animalia Arthropoda Insecta Coleoptera CarnivoresEukaryote Animalia Arthropoda Insecta Diptera SaprovoresEukaryote Animalia Arthropoda Insecta Hymenoptera CarnivoresEukaryote Animalia Arthropoda Chilopoda CarnivoresEukaryote Animalia Arthropoda Diplopoda Carnivores

Eukaryote Animalia Annelida Clitellata Enchytraeidae, Lumbricidae Saprovores

Eukaryote Animalia Mollusca Gasteropoda Herbivores

The animals of each compartment in a German beech forest

Guild Group Main taxa No. of species Individuals x m-2 Biomass (mgDW x m-2)

Microfauna 150 85000000 2000 Microvores Testacea 65 84000000 343 Microvores Nematoda 65 640000 150Mesofauna (saprophagous and microphytophagous) 160 92000 960

Saprovore Enchytraeidae 36 22000 600 Saprovore Cryptostigmata 60 26000 180 Microvores Collembola 50 38000 150Mesofauna (saprophagous and microphytophagous) Gamasina 67 2600 45

Microvores Gamasina 67 2600 45Macrofauna (saprophagous) 300 3500 12000 Saprovores Gastropoda 30 120 400 Saprovores Lumbricidae 11 200 11000 Saprovores Diptera larvae 250 2800 160 Saprovores Isopoda 5 200 40Macrofauna (zoophagous) 250 500 650 Carnivores Araneida 100 170 140 Carnivores Chilopoda 10 190 265 Carnivores Carabidae 24 5 140 Carnivores Staphylinidae 85 100 80Parasitoids 550 400 70 Carnivores Hymenoptera 550 400 70Macrofauna (phytophagous) > 250 1500 200 Herbivores Cecidomyiinae 20 600 80 Herbivores Rhynchota 20 500 20 Herbivores Lepidoptera 150 130 70Vertebrata 30 < 0.01 < 1000 Sum 1700 85000000 16000

The function of the edaphon

Tropical desert

Tropical forest

Grassland Temperate forest

Boreal forest

Tundra Polar desert

Biom

ass

Macrofauna

Mesofauna

Microfauna

Litter breakdown

Soil organic matter accumulation

Decomposers are bacteria and fungi that

reduce organic material

Detritivores are animal or protist

consumers of dead organic matter

Predators feed on soil animals or

protists

Microvores are animal or protist consumers of bacteria and fungi

Decomposers and detritivores

𝑊 𝑡=𝑊 0𝑒−𝑘𝑡

Decomposition of organic matter W is an exponential

process in time t with decomposition constant k

Decomposition rate increases nearly

linearly with nitrogen and phosphorus

content of dead plant material