ECOSYSTEM Created by:Kush Sehgal

Class XII scienceRoll number : 29Session: 2014-

2015

What Is Ecosystem

An ecosystem is a community

of living organisms (plants,

animals and microbes) in

conjunction with the nonliving

components of their environment

(things like air, water and

mineral soil), interacting as a

system.

Niche v/s habitat

Habitat:

The natural home or environment of an animal, plant, or other organism.

Niche:

A role taken by a type of organism within its community.

Biotic Factors Biotic components 

These are the living things that shape an ecosystem.

A biotic factor is any living component that affects another organisms,

including animals that consume the organism in question, and the living food that the

organism consumes.

Example :a fresh water ecosystem showing prey and a predator

More About Biotic Components

Biotic components are contrasted to abiotic components, which are non-

living components of an organism's environment, such as temperature,

light, moisture, air currents, etc. Biotic components usually include:

Abiotic factors In biology and ecology, abiotic components include physical conditions and non-

living resources that affect living organisms in terms of growth, maintenance,

and reproduction. Resources are distinguished as substances or objects in the

environment required by one organism and consumed or otherwise made unavailable

for use by other organisms.

Component degradation of a substance by chemical or physical processes,

e.g. hydrolysis. All non-living components of an ecosystem is called abiotic

components.

productivity I n ecology, pr oduct ivit y or  pr oduct ion r ef er s t o

t he r at e of gener at ion of  biomass in an ecosyst em. I t is usually expr essed in unit s of  mass per unit sur f ace (or volume) per unit t ime, f or inst ance gr ams per squar e met r e per  day (g m-2 d-1). The mass unit may r elat e t o dr y mat t er  or t o t he mass of  car bon gener at ed. Pr oduct ivit y of  aut ot r ophs such as plant s is called pr imar y pr oduct ivit y, while t hat of  het er ot r ophs such as animals is called secondar y pr oduct ivit y.

Producers, Consumers and Decomposers

Pr oducer s, i.e. aut ot r ophs: e.g. plant s, t hey conver t t he ener gy [ f r om phot osynt hesis (t he t r ansf er of sunlight , wat er , and car bon dioxide int o ener gy), or ot her sour ces such as hydr ot her mal vent s] int o f ood.

Consumer s, i.e. het er ot r ophs: e.g. animals, t hey depend upon pr oducer s (occasionally ot her consumer s) f or f ood.

Decomposer s, i.e. det r it ivor es: e.g. f ungi and bact er ia, t hey br eak down chemicals f r om pr oducer s and consumer s (usually dead) int o simpler f or m which can be r eused.

ENERGY FLOW Food chain 

A linear sequence of links in a food web starting from species that are called

producers in the web and ends at species that are called decomposers in the web. A

food chain also shows how the organisms are related with each other by the food

they eat. A food chain differs from a food web, because the

complex polyphagous network of feeding relations are aggregated into tropic species

and the chain only follows linear monophagous pathways.

Types of food chainGrazing food chain - The gr azing f ood chain begins

wit h t he phot osynt het ic f ixat ion of light , car bon dioxide, and wat er by plant s (pr imar y pr oducer s) who pr oduce sugar s and ot her or ganic molecules. Once pr oduced, t hese compounds can be used t o cr eat e t he var ious t ypes of plant t issues. Pr imar y consumer s or her bivor es f or m t he second link in t he gr azing f ood chain.

Detrital food chain  - The det r it us f ood chain dif f er s f r om t he gr azing f ood chain in sever al ways:t he or ganisms making it up ar e gener ally smaller (like algae, bact er ia, f ungi, insect s, & cent ipedes)

t he f unct ional r oles of t he dif f er ent or ganisms do not f all as neat ly int o cat egor ies like t he gr azing f ood chain' s t r ophic levels.

Ecological succession

Ecological succession is the observed process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire), or even millions of years after a mass extinction.

The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community.

Primary succession  is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited.

Secondary succession is one of the two types of ecological succession of plant life. As opposed to the first, primary succession, secondary succession is a process started by an event that reduces an already established ecosystem to a smaller population of species.

Nutrient cycle A nut r ient cycle (or  ecological r ecycling) is t he

movement and exchange of  or ganic and inor ganic mat t er back int o t he pr oduct ion of living mat t er . The pr ocess is r egulat ed by f ood web pat hways t hat  decompose mat t er int ominer al nut r ient s. Nut r ient cycles occur wit hin ecosyst ems. Ecosyst ems ar e int er connect ed syst ems wher e mat t er and ener gy f lows and is exchanged as or ganisms f eed, digest , and migr at e about . Miner als and nut r ient s accumulat e in var ied densit ies and uneven conf igur at ions acr oss t he planet . Ecosyst ems r ecycle locally, conver t ing miner al nut r ient s int o t he pr oduct ion of  biomass, and on a lar ger scale t hey par t icipat e in a global syst em of input s and out put s wher e mat t er is exchanged and t r anspor t ed t hr ough a lar ger syst em of  biogeochemical cycles.

C a r b o n c y c l e The car bon cycle is t he

biogeochemical cycle by which car bon is exchanged among t he biospher e, pedospher e, geospher e, hydr ospher e, and at mospher e of t he Ear t h.

The global carbon budget is t he balance of t he exchanges (incomes and losses) of car bon bet ween t he car bon r eser voir s or bet ween one specif ic loop (e.g., at mospher e ↔ biospher e) of t he car bon cycle. An examinat ion of t he car bon budget of a pool or r eser voir can pr ovide inf or mat ion about whet her t he pool or r eser voir is f unct ioning as a sour ce or sink f or car bon dioxide.

Phosphorus cycle

The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on Earth. The production of phosphine gas occurs only in specialized, local conditions.

On the land, phosphorus (chemical symbol, P) gradually becomes less available to plants over thousands of years, because it is slowly lost in runoff. Low concentration of P in soils reduces plant growth, and slows soil microbial growth - as shown in studies of soil microbial biomass