Energy flow and nutrient cycling
Definitions and key concepts
• Ecology is the study of how organisms interact with
one another and with their physical environment.
• An ecosystem consists of a community of organisms
together with their physical environment.
• Ecosystems can be of different sizes and can be
marine, aquatic, or terrestrial. Broad categories of
terrestrial ecosystems are called biomes.
• In ecosystems, both matter and energy are conserved.
Energy flows through the system—usually from light
to heat—while matter is recycled.
Definitions and key concepts
• An ecosystem is a community of living organisms
(plants, animals, and microbes) existing in
conjunction with the nonliving components of
their environment (air, water, and mineral soil),
interacting as a system. These biotic and abiotic
components are linked together through nutrient
cycles and energy flows.
• An ecosystem is therefore made up of biotic and
abiotic factors.
Definitions and key concepts
• Abiotic factors refers to the non-living
componenr of an ecosystem it can be physical
or chemical in nature: water, light,
temperature, humidity, availability of
chemical elements, wind, etc.
• Biotic factors are the living components of an
ecosystem: relationship between organisms,
presence of parasites, predation etc.
Definitions and key concepts
Definitions and key concepts
Definitions and key concepts
• Habitat- a place within an ecosystem where a
organisms live.
• Species- A group of organisms that have a
common ancestry and so share the same genes
and are capable of breeding together to produce
fertile offsprings.
• A population as a group of organisms of the same
species occupying a particular space at a
particular time that can potentially interbreed.
Definitions and key concepts
• a community is defined as a population of
different species of organisms interacting in a
common Habitat.
• A community can also be defined as an
interacting group of various species in a
common location.
Food chains and trophic levels
Energy Transfers: Food chains and
trophic levels
• Energy that powers our ecosystem comes
from the sun.
• The flow of energy is linear- unlike the flow of
nutrients which is recycled.
• A food chain may be defined as the transfer of
energy and nutrients through a succession of
organisms through repeated process of eating
and being eaten.
Food chains
Food chains
Food chains
Food chains and trophic levels
Food chains
Food chains
Food chains and trophic levels
Another important group of organisms in a feeding relationship are
decomposers
Fungi and bacteria are the
key decomposers in many
ecosystems. Detritivores
include eartworm, woodlice,
,millipedes
Food chains
Decomposers
Food chains
Food chains
Food chains
• Detritus is dead and decaying matter including
the wastes of organisms. It is composed of
organic material resulting from the
fragmentation and decomposition of plants
and animals after they die. Detritus is
decomposed by bacterial activity, which can
help cycle nutrients back into the food chain.
Food chains
• Scavengers are not typically thought to be
detritivores, as they generally eat large
quantities of organic matter, but both
detritivores and scavengers are the same type
of cases of consumer-resource systems.
• After scavengers feed, the left over dead
organic matter is then broken down by
detritivores.
Types of food chains
• Food chains are of three types:
• 1. Grazing food chain
• 2. Parasitic food chain
• 3. Saprophytic or detritus food chain
Types of food chains
Types of food chains
Types of food chains
Food webs
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Energy Flow in Ecosystems
• The energy flow in the ecosystem is important to
maintain an ecological balance.
• The producers synthesise food by the process of
photosynthesis.
• A part of the energy is stored within the plants. The
remaining energy is utilised by the plants in their
growth and development.
• This stored energy is transferred to the primary
consumers when they feed on the producers. This
energy is further passed on to the secondary
consumers when they feed on the primary consumers,
and so on.
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Energy losses along a food chain
