Ecosystem

2-10

% of PAR captured by plants and photosynthetic bacteria to make food

50

% of the incident solar radiation thhat is PAR

pyramid of energy

A pyramid that shows the total amount of energy available at each trophic level.

detritus food chain

DFC - starts with dead organic matter

grazing food chain

GFC - producer --> primary consumer --> secondary consumer

gross primary productivity

GPP

decomposers

Heterotrophic organisms that obtain energy by eating decaying organisms - mainly bacteria or fungi meet energy and nutrient requirements by degrading dead organic matter or detritus

net primary productivity

NPP

photosynthetically active radiation

PAR stands for

saprotrophs

also known as decomposers secrete digestive enzymes that break down dead and waste materials into simple inorganic materials which are subsequently absorbed by them

biogeochemcial cycles

alternative name for nutrient cycling in the ecosystem

primary production

amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis

standing state

amount of nutrients such as carbon, nitrogen, phosphorus, calcium etc. present in the soil at any given time

primary succession

an ecological succession that begins in an area where no living organisms ever existed

secondary consumers

animals that eat other animals that feed on plants or their produce

secondary carnivores

animals that feed on primary carnivores

primary consumers

animals that feed on the producers or the plants

55 billion

annual net primary productivity of oceans (dry weight) in tonnes

170 billion

annual net primary productivity of the biosphere (dry weight) in tonnes

phytoplanktons

autotrophic components of pond ecosystem along with algae and some floating, submerged and marginal plants

NPP

available biomass for the consumption of heterotrophs

secondary succession

begins in areas where natural biotic communities have been destroyed like abandoned farm lands, burned or cut forests, flooded lands

detritivores

break down detritus into smaller particles - earthworm

fragmentation

breaking down of detritus into smaller particles by detritivores like earthworms

standing crop

certain mass of living material that each trophic level has at a particular time

humus

colloid that serves as the reservoir of nutrients in soil

climax community

community that is in near equilibrium with the environment developed due to ecological succession over a long period

heterotrophs

consumers - depend on plants directly or indirectly for their food needs

man-made ecosystems

crop fields, aquarium

humus

dark coloured amorphous substance that is formed by the process of humification

mineralisation

degradation of humus by some microbes to release inorganic nutrients

primary productivity

depends on the plant species inhabiting an area and on variety of environmental factors like availability of nutrients and photosynthetic capacity of plants

phytoplanktons, submerged plants, submerged free floating plants, reed swamp, marsh meadow, scrub, forest

different stages in hydrarch succession from pioneer species to climax community

xeric

dry conditions

pyramid of energy

ecological pyramid that is always upright and never inverted

secondary succession

ecological succession that is faster due to presence of soil

seres

entire sequence of communities that successively change in a given area

terrestrial ecosystems

examples - forest, grassland, desert

aquatic ecosystems

examples - pond, lake, wetland, river, estuary

earthworm

farmer's friend because they help in the breakdown of complex organic matter as well as in loosening the soil

GFC

food chain that is the major conduit for energy flow in aquatic organisms

DFC

food chain through which larger fraction of energy flows through in a terrestrial ecosystem

productivity, decomposition, energy flow, nutrient cycling

four basic components of an ecosystem

ecosystem

functional unit considering productivity, decomposition, energy flow and nutrient cycling

ecosystem

functional unit of nature where living organisms interact among themselves and also with the surrounding environment

ecological succession

gradual and fairly predictable change in the species composition of a given area through change in the diversity of species, increase in the number of species and organisms and increase in total biomass

productivity

has units g m-2 yr-1 or kcal m-2 yr-1

primary production

has units of g m-2 or kcal m-2

ecological pyramids

have the limitations that it does not take into account the same species belonging to more than one trophic level and assumes a simple food chain which does not occur in nature besides saprophytes are not given any place

mesic

having medium water conditions

consumers

heterotrophs - depend on plants directly or indirectly for their food needs

humus

highly resistant to microbial action and undergoes decomposition at an extremely slow rate

pyramid of biomass

illustrates the relative amount of living organic matter available at each trophic level in an ecosystem

producers

in a terrestrial ecosystem, mainly herbaceous and woody plants in an aquatic ecosystem, phytoplankton, algae and higher plants

seral communities

individual transitional communities during ecological succession

decomposition

largely an oxygen requiring process controlled by chemical composition of detritus and climatic factors

10% law

law followed for transfer of energy between successive trophic levels in a GFC

standing crop

measured as biomass or no. in a unit area

ecological pyramids

models that depict the food or energy relationships between organisms at different trophic levels in terms of number, biomass or energy

temperature, soil moisture

most important climatic factors that regulate decomposition through their effects on activities of soil microbes

nutrient cycling

movement of nutrient elements through the various components of an ecosystem without being lost

food web

natural interconnections between food chains in an ecosystem

nitrogen, carbon

nutrient cycles of these elements are gaseous

gaseous nutrient cycles

nutrient cycles with reservoir in the atmosphere

decomposers

organisms that break down complex organic matter into inorganic substances like CO2, water and nutrients

phytoplanktons

pioneer species in hydrarch succession

lichens

pioneer species in primary succession on rock

herbivores

primary consumers that eat plants eg. insects, birds, mammals in terrestrial ecosystem and molluscs in aquatic ecosystem

catabolism

process by which bacterial and fungal enzymes degrade detritus into simpler inorganic substances

leaching

process by which water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts

decomposition

process of breaking down complex organic matter into inorganic substances like CO2, water and nutrients

humification

process which leads to accumulation of humus

productivity

rate of biomass production

secondary productivity

rate of formation of new organic matter by consumers

GPP

rate of production of organic matter during photosynthesis - considerable amount utilised by plants in respiration

detritus

raw material for decomposition made up of dead plant remains such as leaves, bark, flowers and dead remains of animals including faecal matter

pyramid of number

representation of the number of individual organisms in each trophic level of an ecosystem

primary carnivores

secondary consumers that feed on herbivores

lichens

secrete acids to dissolve rock helping in weathering and soil formation

pond

shallow water body; self-sustainable unit water with dissolved inorganic and organic substances rich soil deposit at the bottom solar input, temperature cycle, day-length, climate

inverted

shape of pyramid of biomass in oceans/sea

inverted

shape of pyramid of number for insects feeding on a big tree

zooplankton

small free-floating animals that form part of plankton that are consumers

secondary succession

species of invasion depends on soil condition, water availability, environment and seeds or propagules present

pioneer species

species that invade a bare area

trophic level

specific place in the food chain that organisms occupy based on the source of their nutrition and food

lignin, chitin

substances in detritus that can slow decomposition down

nitrogen, sugars

substances in detritus that can speed up decomposition reactions

secondary succession

succession taking place in areas that lost all the living organisms that existed there

primary succession

succession that is slower, and requires formation of soil depending on the climate may take several hundred to thousands of years

xerarch succession

succession that takes place in dry areas and series progresses from xeric to mesic conditions

hydrarch succession

succession that takes place in wetter areas and the successional series progresses from hydric to mesic conditions

ecological succession

takes place in areas where no living organisms are there - either from areas where no living organisms ever existed or in areas that somehow lost all living organisms

primary succession

takes place on newly cooled lava, bare rock, newly created pond, reservoir

fragmentation, leaching, catabolism, humification, mineralisation

the important steps in the process of decomposition

biomass

the total mass of organisms in a given area or volume.

sun

the ultimate source of energy for all living things of an ecosystem

stratification

vertical distribution of different species occupying different levels of an ecosystem

dry weight

weight of biomass which is more accurate

hydric

wet conditions