Primary productivity, trophic levels, food webs, biogeochemical cycles (C/N/P/S/H2O).
Ecosystem Ecology
Primary productivity (GPP, NPP)
GPP: gross photosynthetic C fixation. NPP = GPP − autotrophic respiration. NPP ~55 PgC/yr terrestrial + ~50 PgC/yr ocean. Basis of all…
Food web
Network of trophic (feeding) links among species in a community. Nodes = species, edges = consumption. Properties: connectance, length of…
Carbon cycle
Global flows of C between atmosphere, biosphere, ocean, pedosphere, lithosphere. Photosynthesis: 120 PgC/yr; respiration + decomposition:…
Nitrogen cycle
Microbially-mediated transformations: N2 fixation (→NH3), nitrification (NH3 → NO2- → NO3-), assimilation, ammonification, denitrification…
Phosphorus cycle
Sedimentary cycle (no significant gas phase). Weathering from rock → soil → plants → animals → decomposition. Often limits primary…
Decomposition
Breakdown of dead organic matter by detritivores + saprotrophs (fungi, bacteria). Returns elements to biogeochemical pools. Rates vary 100×…
Ecosystem services
Benefits humans derive from functioning ecosystems. Provisioning (food, water), regulating (climate, flood), supporting (nutrient cycling),…
Trophic pyramid & 10% rule
Only ~10% of energy at each trophic level transfers upward (Lindeman 1942). Sets limit on food-chain length and biomass of top predators.
Water cycle (biological component)
Evapotranspiration from plants returns ~60% of land precipitation to atmosphere. Forests modulate regional precipitation. Deforestation…
Biomagnification
Lipid-soluble persistent pollutants (DDT, PCBs, mercury) concentrate up food chains. Silent Spring (Carson 1962); motivated environmental…
Redfield stoichiometry biogeochemistry
Redfield 1934: marine plankton elemental ratio C:N:P = 106:16:1 mirrors deep-ocean dissolved nutrient ratios. Reframes ecosystem nutrient…
Ecosystem energy flow (Lindeman trophic dynamics)
Lindeman 1942: ecological efficiency ε = production_n+1 / production_n ~ 10% transfers across trophic levels; Eltonian biomass pyramid…
Net primary productivity (Lieth 1973)
H Lieth 1973 global NPP ~120 PgC/yr terrestrial + ~50 PgC/yr ocean; Miami + Thornthwaite-Mather climate-driven models; basis of…
Mauna Loa + carbon cycle (Keeling 1958)
Charles Keeling 1958-2005 Mauna Loa CO2 record: 315 ppm 1958 -> 422 ppm 2024; +2.5 ppm/yr modern accumulation; ~50% airborne fraction.
Nitrogen cycle (Galloway 2003)
Galloway 2003 anthropogenic-N: Haber-Bosch + fossil + cultivation N-fixation now exceeds natural ~150-200 TgN/yr; planetary-boundary…
Ecosystem services (MEA 2005)
Millennium Ecosystem Assessment 2005 + Costanza 1997: 4 categories (provisioning/regulating/cultural/supporting); $125 trillion/yr value…
Alternative stable states (Scheffer 2001)
M Scheffer 2001 + Folke 2004: ecosystems exhibit hysteretic regime-shifts; lake eutrophication + coral-reef bleaching; early-warning…
Redfield ratio (1958)
Alfred Redfield 1958 marine plankton C:N:P = 106:16:1; tight stoichiometric coupling; modern Sterner-Elser 2002 ecological-stoichiometry…
Lindeman trophic (1942)
R Lindeman 1942 trophic-dynamic; modern modern foundational text + ecosystem-energy-flow + 2024 deep-learning food-web inference.
Odum (1953)
E Odum-H Odum 1953 'Fundamentals of Ecology'; modern modern foundational text + ecosystem-services + 2024 ecological-economics globe value.
Biogeochemistry (Vernadsky 1926)
V Vernadsky 1926 biosphere; modern modern foundational + Hutchinson 1957 niche + 2024 Earth-system-science deep-time C-cycle reconstruct.
NPP (Lieth 1975)
H Lieth-R Whittaker 1975 NPP global-Lieth-formula; modern modern foundational text + 2024 satellite-MODIS + ML downscaling vegetation NPP.
Invasions (Elton 1958)
C Elton 1958 'The Ecology of Invasions'; modern modern foundational text + 2024 IPBES global-invasive species 37k species threat-assessment.
MA (Millennium 2005)
Millennium Ecosystem Assessment 2005; modern modern foundational text + IPBES 2019 + 2024 nature-positive economic-policy net-zero…