Ecosystem Flashcards
Ecosystem
Sum total of interaction between living (biotic) and non-living (abiotic) components capable of independent existence
Biotic factors
Living elements of a habitat which affect the ability of a group of organisms to survive there
Abiotic factors
Non-living factors that can determine the ability of an organism to succeed within a particular habitat
Food chain
The sequence of living organisms in an ecosystem in which one organism consumes another organism to transfer food energy
Grazing food chain
Living plants –> Grazing herbivores –> Carnivores
Dependent on influx of solar radiation
Detritus food chain
Dead organic matter of decaying plants/animals –> Micro-organisms –> Animals feeding on detritus (detritivores)
Dependent on influx of organic matter produced in another system
Trophic levels
- Trophic levels are levels or positions at which species feed
- Each step in the food chain represents a trophic level
- Represent a stepwise transfer of food and the energy contained in food
Food web
Interconnected food chains operating in an ecosystem which establish a network of relationships between various species is called a food web
What is an ecological pyramid
Ecological pyramids are diagrammatic representations showing the relationship between biomass, number and energy contents at different trophic levels
Pyramid of energy
Shows the rate of energy flow and/or productivity at successive trophic levels
Upright
Pyramid of numbers
Shows the relationship between producers and consumers at successive trophic levels in terms of their numbers
Pyramid of biomass
The ecological pyramid constructed on the basis of biomass of the organisms at each trophic level is called pyramid of biomass
Abiotic components of pond ecosystem
Physical environment like soil, water and air along with inorganic components
Solar input, temperature, day length and climatic conditions regulate the rate of function of the pond
Biotic components of pond ecosystem
The various organisms that constitute the biotic components are producers, consumers, and decomposers
Producers: autotrophic plants e.g. Hydrilla, Vallisneria and phytoplanktons
Consumers: Heterotrophs feeding on phytoplanktons as well as living plant parts
Decomposers: heterotrophic microbes e.g. Aspergillus, Penicillium
Productivity
The rate at which radiant energy is fixed in the form of an organic food due to photsynthetic and chemosynthetic activity of producers is called productivity
GPP
Gross Primary Productivity
It is defined as the total rate of photosynthesis during the measurement period
NPP
Net Primary Productivity
It is defined as the rate of storage of organic matter in plants in excess of the organic matter used up in respiration during the period of measurement
Also known as net assimilation
NPP = GPP - R
R- respiration
Secondary productivity
Rate of storage of organic matter at consumer levels
Decomposition
Process whereby decomposers breakdown complex organic matter into inorganic substances like carbon dioxide, water and nutrients
Main steps of decomposition
- Fragmentation
- Leaching
- Catabolism
- Humification
- Mineralisation
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Fragmentation
Breakdown of detritus by detritivores into smaller particles e.g. earthworm, woodlice, maggots
Leaching
Leaching is the process where water soluble inorganic nutrients go down into the soil horizon and got precipitated as unavailable salts
Catabolism
Process whereby detritus is degraded into simpler inorganic substances by bacterial and fungal enzymes
Humification
Accumulation of humus
Humus is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. Being colloidal in nature, it serves as a reservoir of nutrients
Mineralisation
The humus is further degraded by some microbes and release of inorganic nutrients occurs by the process known as mineralisation
PAR
Photosynthetically Active Radiation
radiation absorbed by plants to carry out the photosynthesis process.
400 - 700 nm
Standing crop
Amount of living matter present in a component population at any time in the ecosystem
Standing state
Amount of inorganic substances present at any given time in the environment of an ecosystem
