Sedimentary cycle. There is exchange of materials between the living and non-living world. This is called cycles of matter. The sedimentary cycle involves minerals, such as phosphorus, sulphur and calcium, the reservoir is lithosphere.

(a) Two examples of man-made ecosystems are: Gardens and parks, crop fields and fishery tanks.
(b) Salient features of man-made ecosystems:
(i) These are simple and highly efficient.
(ii) These are generally monoculture (e.g. field crops) with low biodiversity.
(iii) These are generally unstable
(iv) These are more vulnerable to sudden changes because of low biodiversity, stability and self-regulation.

(a) Removal of all producer reduce primary production in the ecosystem. Hence, no biomass will be available to the successive/higher trophic level or heterotrophic organisms.
(b) Elimination of all organisms of herbivore level results into an increase in primary productivity and biomass of producer and the carnivorous animal will not survive due to inavailability of food due to the elimination of herbivores.
(c) Removal of top carnivores also disturbs the ecosystem as it will result in huge increase in a number of herbivores which will finish plants creating desertification.

Three above statements do not mean one and the same thing because:
(i) Statement (a) indicates total productivity of wheat but does not indicate the extent of area.
(ii) Statement (b) indicates productivity of wheat/acre on a specific day.
(iii) Statement (c) indicates productivity of wheat/acre/specific period.

Pond - an Ecosystem
1. Pond is a fairly self-sustainable unit that shows even complex interactions of an aquatic ecosystem.
2. It is a shallow water body in which all the major/basic components of an ecosystem are well exhibited.
3. The abiotic components ar:
(i) Water with all the dissolved inorganic substance.
(ii) The rich soil deposit at the bottom.
(iii) The solar input.
(iv) The cycle of temperature.
(v) day length.
(vi) Climatic factor.
1. The producers or autotrophic components include phytoplanktons, some algae, floating and submerged and marginal plants.
2. The consumers are represented by
(i) zooplanktons,
(ii) f ree-swimming animals,
(iii) bottom dwelling animals.
1. The decomposers are the bacteria and fungi that are found at the bottom.
2. This system performs all the function of an ecosystem.
(i) Conversion of inorganic materials into organic compounds with the help of radiant energy of sun.
(ii) Consumption of autotrophs  by heterotrophs, (food chain/food web), decomposition and mineralisation (nutrient cycling), etc.

b)

Components of an Ecosystem:
The components are broadly classified into two categories:
(i) Biotic components
(ii) Abiotic components

Biotic components include the following:

Producers:
These are the green plants or other autotrophs, which prepare their own organic food and feed energy into the ecosystem.
Decomposers:
Decomposers are the organisms which degrade the dead and decaying organic matter and satisfy their energy requirement, e.g. bacteria and fungi.

Abiotic Components:
They include the factors like:
(i) Air
(ii) Water
(iii) Solar radiation
(iv) Temperature
(v) Soil with organic and inorganic compounds as nutrients to plants.

1. Hydrarch succession begins in water bodies or water areas and the successional stages process from hydric to mesic conditions.
2. The pioneers are the microscopic phytoplanktons,Which are replaced by the free floating angiosperms, followed by rooted hydrophytes, sedges, grasses and finally trees; the climax would be a forest.
3. Xerarch succession starts in dry areas (bare rocks) and progresses from xeric to mesic conditions.
4. The species that invade a bare rock, are usually lichens,which secrete some acids to dissolve the rock and help in weathering and soil formation.
5. This paves way to bryophytes which can take hold in small amount of soil.
6. They are replaced with time by bigger plants and ultimately a climax forest community is formed.
7. The climax community in both hydrarch and xerarch succession is a mesic forest.

1. Carbon cycling occurs through atmosphere, oceans and living and dead organisms. About 49% of dry weight of organisms is constituted by carbon.
2. Carbon dioxide in the atmosphere and fossil fuel represent the reservoir of carbon.
3. About 71% of the global carbon is found dissolved in the ocean and this oceanic reservoir regulates the amount of carbon dioxide in the atmosphere.
4. About 4 x 1013 kg of carbon is fixed in the biosphere through photosynthesis annually.
5.  A considerable amount of this is returned to the atmosphere as carbon dioxide through the respiratory activities of producers and consumers and decomposition by decomposers.
6. Some amount of fixed carbon is lost as sediments (limestone, dolomite, etc.)
7. Carbon dioxide is also returned to the atmosphere through :
(I) Respiration of living organisms
(ii) Forest fires
(iii) Volcanic activity and
(iv) Burning of fossil fuels, fuel wood and organic debris.

Process of decomposition
(i) Fragmentation:
It is the process of breaking of the detritus into smaller particles by detritivores like earthworm.
(ii)Leaching:
It is the process in which water-soluble inorganic substances run down into soil horizon and get precipitated as unavailable salts.
(iii) Catabolism:
The enzymatic conversion of the detritus into simple organic compounds and then into inorganic compounds, is called catabolism.
The enzymes are secreted by the decomposers like bacteria and fungi.
(iv) Humification:
Humification during decomposition leads to the accumulation of a dark coloured, amorphous substance, called humus.
(v) Mineralisation:
It is the process in which the humus is degraded by certain microbes and the inorganic nutrients are released.