Raymond L. Lindeman ( ) Energy and nutrient cycles Lindeman’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 ( ) 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 -1 Net primary productivity (unit= kg×year -1 ) Modified from Geider et al. 2001, Gl Change Biol, 7 Variability in gross primary productivity (unit= 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 PlantsAnimalsBacteriaHumans Wind Atmosperic water Only 0.023% ( Watt) of the incoming radiation of the sun is converted in organic matter 100% = Watt The earth energy budget Fungi

Atmosphere Biosphere Pedosphere Litosphere Ground water Hydrosphere O2O2 O2O2 O2O2 O2O2 O3O3 O H2OH2O H2OH2O H OH O O2O2 UV CO O 2 +2CO→ 2CO 2 O 2 +4FeO→ 2Fe 2 O 3 Bleaching Vulcanism Water cycle The global oxygen cycles Photo- synthesis Respiration 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 Bacteria Atmos- phere

100% The energy budget of the biosphere 17% 83% 40% 1-3% 57% 3% 57% 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. Consumption efficiencyTransfer efficiencyAssimilation efficiencyProduction efficiency P: Production at trophic level nI: Consumption at trophic level n P: Assimilation at trophic level n

The global cycle of potentially biologically active carbon Reactive sediments >6,000 Fossil carbon >5,000 Atmosphere 720 × kg Ocean surface Deep ocean 1, Soil carbon 2,300 Plant and fungal biomass 600 Photosynthesis 123 Plant respiration 50 Microbial respiration 60 Human emissions 7.7 Land use 1.5 Deposition 13 Average Annual Carbon Fluxes for the period (Modified from LeQuéré et al., 2009) Th annual increase of athmospheric carbon from fossil fuel burning

The Nitrogen cycles Rain N2N2 Nitrogen fixation Phytoplankton Marine food web NH 4 OH Nitrification NO 3 - Denitrification N2N2 N recycling Euphotic zone Dark zone Atmosphere N recycling The marine nitrogen cycle The soil nitrogen cycle Atmosphere Rain N2N2 Soil symbiontic Rhizobium Decomposer anerobic Bacteria, Fungi NH 4 OH free living Azotobacter NH 4 OH Nitrification Nitrosomonas NO 2 - NO 3 - Denitri- fication Ammoni- fication Nitro- bacter Clostri- dium; Pseudo- monas N2N2 Leaching into ocean water

The succession of nutrient uptake can be traced by radioactive markers 32 P 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 ( ) Examples of ecosystems: LakesForestsGrasslands MangrovesTundrasShrublands Coral reefGeothermal ventsDeserts Habitats that are not ecosystems in a strict sens: RiversOceansAgricultures A community is a group of species that potentially interact An 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 O 2, CO 2, H 2 0LightO 2, CO 2, H 2 0 Mineral sink A simple scheme of an ecosystem

Regulated or not regulated? 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 system Statistical averaging

Control loop Early ecological theory saw ecosystems as self regulated entities. Examples: Predator – prey relationships Degree of herbivory Energy flux Population densities Productivity Biodiversity 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

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 Variance Stability 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 DomainKingdomPhylumClass/OrderExamplesEcological function ProkaryoteBacteriaProteobacteria Nitrosomonas, Nitrobacter, Rhizobium, Azotobacter N cycle ProkaryoteBacteriaFirmicutes ClostridiumN cycle EukaryoteFungiAscomycota Penicillium, Aspergillus, Fusarium, Trichoderma Saprovores EukaryoteChromalveolata DiatomeaPrimary producers EukaryoteChromalveolata XanthophyceaePrimary producers EukaryoteChromalveolata CiliophoraMicrovore EukaryoteAmoebozoa AmoebaMicrovore EukaryotePlantaeChlorophyta Primary producers EukaryoteAnimaliaNematoda Bacteriovores EukaryoteAnimaliaRotifer Saprovores EukaryoteAnimaliaTardigrada Bacteriovores EukaryoteAnimaliaArthropodaCollembola Fungivores EukaryoteAnimaliaArthropodaArachnidaAcarinaSaprovores, Carnivores EukaryoteAnimaliaArthropodaArachnidaPseudoscorpionidaCarnivores EukaryoteAnimaliaArthropodaInsectaColeopteraCarnivores EukaryoteAnimaliaArthropodaInsectaDipteraSaprovores EukaryoteAnimaliaArthropodaInsectaHymenopteraCarnivores EukaryoteAnimaliaArthropodaChilopoda Carnivores EukaryoteAnimaliaArthropodaDiplopoda Carnivores EukaryoteAnimaliaAnnelidaClitellataEnchytraeidae, LumbricidaeSaprovores EukaryoteAnimaliaMolluscaGasteropoda Herbivores

The animals of each compartment in a German beech forest GuildGroupMain taxaNo. of speciesIndividuals x m -2 Biomass (mgDW x m -2 ) Microfauna MicrovoresTestacea MicrovoresNematoda Mesofauna (saprophagous and microphytophagous) SaprovoreEnchytraeidae SaprovoreCryptostigmata MicrovoresCollembola Mesofauna (saprophagous and microphytophagous) Gamasina MicrovoresGamasina Macrofauna (saprophagous) SaprovoresGastropoda SaprovoresLumbricidae SaprovoresDiptera larvae SaprovoresIsopoda Macrofauna (zoophagous) CarnivoresAraneida CarnivoresChilopoda CarnivoresCarabidae CarnivoresStaphylinidae Parasitoids CarnivoresHymenoptera Macrofauna (phytophagous) > HerbivoresCecidomyiinae HerbivoresRhynchota HerbivoresLepidoptera Vertebrata 30< 0.01< 1000 Sum

The function of the edaphon Tropical desert Tropical forest Grassland Temperate forest Boreal forest Tundra Polar desert Biomass 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 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