(PLANT RESP)
(HETEROTROPH)
Ecological Productivity
30 Ontological Micro-Realms · GPP, NPP, Secondary Productivity, NEP & Controlling Factors
The 30 Ontological Nodes of Realm 21
Ultra-Crisp 2-to-5-Word Architectural Portals
Productivity vs Biomass
- Biomass: static standing-crop
- Productivity: rate of-generation
- Flow per unit-time
- High-turnover low-biomass paradox
Productivity Units
- Dry organic matter-mass
- Grams carbon per-m²-per-year
- Calorific energy equivalents
- 1g dry-biomass ≈ 4.5-kcal
Primary Productivity
- Autotrophic energy fixation-rate
- Photosynthesis and chemosynthesis
- Inorganic CO2 to-organic-carbon
- Foundational trophic fuel-supply
Gross Primary (GPP)
- Total carbon fixed-by-plants
- Includes respiratory expenditure
- Total photosynthesis rate
- Measured via chlorophyll-fluorescence
Autotrophic Respiration (Ra)
- Plant mitochondrial ATP-use
- Maintenance and growth-respiration
- Root stem leaf-metabolism
- Consumes 40–70% of-GPP
Net Primary (NPP)
- Net stored plant-biomass
- Apparent photosynthesis rate
- Available to herbivores-decomposers
- Determines consumer carrying-capacity
ANPP vs BNPP Allocation
- Aboveground wood foliage-fruit
- Belowground fine-roots exudates
- Grasslands >60% belowground-BNPP
- Optimal partitioning resource-theory
Carbon Use Efficiency
- Ratio CUE = NPP / GPP
- Global average ~0.47–0.50
- Higher in young-stands
- Drops in warm-old-forests
Secondary Productivity
- Heterotrophic biomass generation-rate
- Herbivores carnivores decomposers
- Re-synthesis of ingested-organics
- Somatic growth plus-reproduction
Consumer Energy Budget
- Ingestion (I) minus Feces (F)
- Equals Assimilation (A)
- Assimilation minus Respiration (R)
- Equals Secondary Production (P)
Secondary Assimilation Rule
- Not divided into-Gross/Net
- Consumers only re-package-food
- Assimilated energy = Gross-intake
- Odum terminology convention
Ecosystem Respiration (Re)
- Total biotic CO2-efflux
- Autotrophic plant respiration (Ra)
- Heterotrophic animal-microbe respiration (Rh)
- Soil respiration dominates-Rh
Net Ecosystem (NEP)
- Also NEP = NPP − Rh
- Net Community Productivity (NCP)
- Positive in growing-forests
- Near-zero at mature-climax
NEE & Net Biome (NBP)
- NEE: atmospheric CO2-flux-sign
- NBP: regional landscape-balance
- Subtracts fire harvest-leaching
- True long-term carbon-sequestration
Global 170-Billion-Ton NPP
- Total biosphere ~170B-tons/yr
- Land (29% area): 115B-tons
- Ocean (71% area): 55B-tons
- Field 1998 satellite-synthesis
Peak-Productivity Ecosystems
- Tropical rainforests (~2200 g/m²/yr)
- Swamps and marshes (~2000)
- Coral reefs and-algal-beds (~2500)
- Estuaries and sugarcane-fields
Moderate-Productivity Biomes
- Temperate deciduous forests (~1200)
- Boreal taiga forests (~800)
- Savannas and grasslands (~600–900)
- Continental shelf waters (~360)
Low-Productivity Deserts
- Tundra and alpine (~140 g/m²/yr)
- Open pelagic ocean (~125)
- Arid desert scrub (~90)
- Extreme rock-ice deserts (<3)
Open Ocean Paradox
- Lowest unit-area rate (125g)
- Biological desert per-m²
- Yet huge 360M-km²-extent
- Yields ~1/3 global-NPP
Factor 1: Light & LAI
- Latitudinal solar-insolation gradient
- Leaf Area Index (LAI)
- Canopy architecture interception
- Aquatic turbidity-depth attenuation
Factor 2: Thermal Regime
- RuBisCO enzymatic kinetics
- Frost-free growing-season length
- 365-day equatorial vs-60-day-Arctic
- Excess heat spikes-Ra
Factor 3: Moisture & AET
- Rosenzweig 1968 AET-predictor
- Actual Evapotranspiration combines-heat+water
- Stomatal conductance trade-off
- Water Use Efficiency (WUE)
Factor 4: N & P Limitation
- Nitrogen limits temperate-young-soils
- Phosphorus limits ancient-tropical-oxisols
- Phosphorus limits freshwater-lakes
- Nitrogen limits coastal-seas
Factor 5: Oceanic Iron (HNLC)
- John Martin Iron-Hypothesis
- High-Nutrient Low-Chlorophyll (HNLC)
- Southern Ocean pelagic-gyres
- Permanent thermocline blocks-nutrients
Factor 6: Upwelling Subsidies
- Ekman coastal wind-upwelling
- Peru California Benguela-currents
- Pumps deep benthic-nitrates-phosphates
- Fuels world's richest-fisheries
Factor 7: CO₂ & C3/C4
- C4 suppresses photorespiration
- Sugarcane maize sorghum-champions
- CO2 fertilization effect (FACE)
- Constrained by soil-nitrogen
Harvest Measurement Method
- ΔB = (W2 − W1) + L + G
- Oven-dry quadrat clipping
- Best for crops-grasslands
- Measures Net Primary-Productivity
Light & Dark Bottle Method
- Gaarder and Gran-1927
- Light bottle: measures-NPP (O2)
- Dark bottle: measures-Respiration
- Light minus Dark = GPP
¹⁴C, Flux Towers & NDVI
- Steemann-Nielsen ¹⁴C-uptake
- Eddy-covariance micrometeorological towers
- Satellite NDVI and-SIF
- Global real-time GPP-monitoring
Human Appropriation (HANPP)
- Vitousek Haberl HANPP-metric
- Humans co-opt ~25% land-NPP
- Harvest land-conversion fires
- Bridge to Realm-22
Core Ontological Distinctions
1. GPP vs. NPP vs. NEP (The Three Equations)Gross Primary Productivity ($GPP$) is the total solar energy/carbon fixed by autotrophs. Net Primary Productivity ($NPP = GPP - R_a$) subtracts only autotrophic plant respiration ($R_a$) and represents the food available to consumers. Net Ecosystem Productivity ($NEP = GPP - R_e = NPP - R_h$) subtracts both plant ($R_a$) and heterotrophic animal/decomposer respiration ($R_h$), showing net ecosystem carbon storage.
2. Primary Productivity vs. Secondary ProductivityPrimary Productivity is the synthesis of organic matter from inorganic raw materials ($CO_2, H_2O$) by autotrophs. Secondary Productivity is the rate of formation of new organic biomass by heterotrophic consumers (herbivores, carnivores, decomposers) from already-preformed organic food. Unlike primary productivity, secondary productivity is not divided into Gross and Net.
3. Why Open Oceans Have Low Productivity Per $m^2$ Despite Unlimited Water & LightOn land, water and temperature (measured together as Actual Evapotranspiration, AET) are the primary limiting factors of NPP. In the open pelagic ocean, water is infinite, but a permanent thermocline traps dead sinking nutrients in the dark abyss, leaving surface sunlit waters severely starved of Nitrogen, Phosphorus, and Iron (Fe)—except in coastal upwelling zones and estuaries.
Realm 21 Complete
All 30 nodes of **Realm 21: Ecological Productivity** (`21.01` to `21.30`) are forged. Next in the **World B** sequence is **Realm 22: Models of Energy Flow** (`[022 / 266]`).