2.3, 2.4: Ecosystems and Ecology

2.3 - Flows of Energy and Matter

Productivity: conversion of energy into biomass over a given period of time. It is the rate of growth or biomass in plants and animals
Gross: total amount of something made as a result of an activity
Net: amount left after deductions are made; what you have left, always lower than the gross amount
Gross productivity: total gain in energy or biomass of an organism before any reductions
Net productivity: gain in energy or biomass that remains after deductions due to respiration
Gross primary productivity: total gain in energy or biomass by green plants. It's the energy converted from light to chemical energy by photosynthesis in green plants
Net primary productivity: total gain in energy or biomass by green plants after allowing for losses to respiration. The increase in biomass of the planet and is the biomass that is potentially available to consumers that eat plants
Glucose produced in photosynthesis:
- Provides for growth, maintenance and reproduction with energy being lost as heat during respiration
- Rest is deposited in and around the cell
- NPP = GPP - R
- Net secondary productivity (NSP): total gain in energy or biomass by consumers after allowing for losses to respirate
- GSP = food eaten - faecal loss
Biogeochemical cycles: the natural pathways by which essential elements of living matter are circulated
- 4 main cycles: water, carbon, nitrogen, sulphur
- plants use carbon dioxide to make food (photosynthesis) carbon becomes stored food
Nitrogen Cycle:
- nitrogen fixation: when atmospheric nitrogen is made available to plans through fixation of atmospheric nitrogen
- nitrification: nitrifying bacteria in the soil which are able to convert ammonium to nitrates
- denitrification: denitrifying bacteria in waterlogged and anaerobic conditions
- decomposition of dead animals provides nitrogen for uptake by plants
- decomposition of dead animals provides nitrogen for uptake by plants
Efficiency of assimilation: gross productivity * 100 / food eaten
Efficiency of biomass productivity: net productivity *100 / gross productivity

→ Energy budget: can measure the quantities of energy entering and leaving the animal or population

→ Maximum sustainable yield: largest crop or catch that can be taken from the stock of a species without depleting the stock

2.4 - Biomes, Zonation, and Succession

Biome: is a collection of ecosystems sharing similar climatic conditions
- Aquatic: fresher and marine, freshwater, marine.
- Deserts, forest, tundra, grassland
Biosphere: part of the earth inhabited by organisms
- Latitude: distance north or south from the equator
- Altitude: height above sea level
Zonation: change in community and ecosystem aking and environmental gradient due to changes in altitude, latitude, tidal level or distance from shore/coverage by water
Primary succession: process of creating life in an area where no life previously existed
Secondary succession: when an established community is suddenly destroyed, an abridged version of succession starts
A sub-climax community is one which will only continue its development if the limiting factor is removed