Community and Ecosystem

 
9.1 Community and Ecosystem
 
  • Organisms not only interact with each other, but also interact with non -living things to form a balanced system known as an ecosystem.
 

Habitat:

  • Habitat is the natural environment or abode of an organism
  • Bird habitat in the forest
  • Habitat of frogs in ponds
 

Species:

  • A species is a group of similar organisms, able to reproduce and produce offspring
 

Population:

  • A population is a group of organisms of the same species and living in the same habitat
 

Community:

  • Communities are all populations of organisms of different species that live in one habitat and interact with each other.
 

Ecosystem:

  • An ecosystem is a number of communities that live together in one habitat, interacting with each other including with non -living components (abiosis) such as water, air and soil.
 

Niche:

  1. Niche is the role of an organism in an ecosystem that includes its behavior and interaction with the components of biosis and abiosis in its habitat environment.
  • Ecological niche: the role of a species in its surroundings
  • Species niche: the way in which a species interacts with biotic and abiotic components within its surroundings
 
Biotic components Abiotic components:
  • Producers
  • Consumers
  • Decomposers
  • pH value
  • Temperature
  • Light intensity
  • Topography
  • Microclimate
  • Air humidity
 

pH value:

  • The pH value of the soil greatly affects the distribution of organisms in a habitat
  • Most suitable organisms live in neutral or near -neutral pH conditions.
  • Soil is home to hundreds of millions of worms and microorganisms such as bacteria, fungi and protozoa.
 

Temperature:

  • Ambient temperature affects the physiological activities of plants and animals.
  • Small temperature changes will lower the rate of metabolism because all the enzymes that catalyze physiological responses are very sensitive to temperature changes.
  • Although most organisms can survive in a temperature range between 20 degrees Celsius to 40 degrees Celsius, there are also organisms that can survive in extreme temperatures.
  • Polar bears can live in tundra habitats with temperatures of -14 degrees Celsius while foxes can live in the desert with temperatures reaching 45 degrees Celsius during the day.
 

Light intensity:

  • The intensity of light and the length of time that sunlight radiates in an area greatly affects the distribution of organisms, especially plants that carry out photosynthesis.
  • Tall trees exposed to high light intensity in tropical rainforest areas form a canopy of low light intensity below.
  • Only small plants such as ferns can live under this canopy
  • Moderate climate coniferous forests with low light intensity have less plant density.
  • The trees in the coniferous forest are small and low in size
 

Topography:

  • Topography is the physical feature of the earth's surface that includes altitude, gradient and aspect
    Topography determines humidity, temperature, and light intensity in an ecosystem.
 

Microclimate:

  • Microclimate refers to the climatic conditions of a small area that are different from the surrounding area
  • The microclimate may occur under rocks or under large thickets of trees in the forest canopy
  • The microclimate depends on temperature, humidity, light intensity, heat balance, atmospheric pressure, water evaporation as well as the ability of the soil to retain water in the area to retain moisture.
 

Air humidity:

  • Air humidity is the quantity of water vapor in the air that affects the distribution of organisms in a habitat
  • More organisms inhabit areas of high humidity
  • Low air humidity increases water loss from the stoma through transpiration
  • Transpiration also exerts a cooling effect on the plant to maintain the optimum temperature of enzyme action 
 

Autotrophic and heterotrophic nutrition:

  • Nutrition is the way organisms obtain nutrients and energy from food eaten for life processes
  • There are two types of nutrients, namely autotrophic and heterotrophic.
 

Autotrophic nutrition:

  • Photoautotrophic
  • Chemoautotrophic
 

Photoautotrophic:

  • Photoautotropic are organisms that synthesize organic compounds from carbon dioxide and light energy.
  • Photoautotrophic can synthesize food on their own through the process of photosynthesis
  • Example: Green plants
 

Chemoautotrophic:

  • Chemoautotrophic include several types of bacteria that synthesize organic compounds without the use of light.
  • Chemoautotrophic obtain energy through the oxidation of inorganic substances such as hydrogen sulfide and ammonia through chemosynthesis
  • Example: Nitrobacter sp.
 

Heterotrophic:

  • Saprotrophic
  • Holozoic
  • Parasitic
 

Saprotrophic:

  • Saprotrophic are saprophytic organisms that obtain nutrients from dead and decaying organic matter.\
  • Digestion is done outside the body of the organism before nutrients are absorbed into the body.
  • Example: Fungi
 

Holozoic:

  • Organisms that consume solid organic matter which then digests it and is absorbed into the body.
  • Humans and almost all types of animals are holozoic.
  • Example: Squirrel
 

Parasitic:

  • Parasitic are organisms that absorb nutrients from a host.
  • For example, fleas and tapeworms that absorb nutrients from their hosts are humans.
  • Example: Fleas
 

Biotic components according to trophic levels:

  • The biotic component consists of organisms that need energy to carry out life processes.
  • Humans and animals obtain energy by eating other organisms including photosynthetic plants.
  • Therefore, the most important source of energy for all organisms comes from the sun.
  • The components of biosis consist of three groups, namely producers, consumers and decomposers
 

Energy flow in the food chain:

  • Organisms in an ecosystem interact with each other in the form of nutritional relationships.
  • Such relationships are shown in the food chain.
    The food chain is a sequence of energy transfers from one trophic level to the next trophic level, starting from the producer.

In a food chain:

  • It starts with the producer and ends with the secondary consumers or the tertiary consumers
  • The organism will eat the organism from the previous trophic level
  • Energy is transferred from the organism that eats it to the organism that eats it
  • Organisms that eat other organisms get energy from the body tissues of the organism money is eaten. This energy is transferred to the organism when food is digested and assimilated to form new tissues

In a food web:

  • Describe the nutritional relationship in a community
  • Formed from several food chains
  • Organisms in all food chains are interdependent with each other in aspects of nutrition
  • Initiated by producers who photosynthesize and convert light energy from the sun into chemical energy in the form of food stored in root organs, fruits, stems or leaves.
 

Ecological pyramids:

  • Food chains and food webs describe nutritional relationships between organisms.
  • When one organism eats another organism, energy transfer occurs.
  • In a nutritional interaction, as the trophy level increases, the number of individuals, biomass and the amount of energy contained in each individual for each trophy level will change.
  • All these factors can be described in the form of an ecological pyramid consisting of a number pyramid, a biomass pyramid and an energy pyramid.

Pyramid of numbers:

  • The bottom most has the largest number and is the first trophic level that represents the number of producers
  • The next part of the pyramid is the second, third and fourth trophic levels which represent the number of primary users, secondary users and tertiary users
  • The higher to the top of the pyramid, the fewer the number of organisms in each of the levels and the larger the size of the organisms

Pyramid  of biomass:

  • The pyramid also depicts the biomass that can be supplied to organisms in the next trophic level
  • For example, the amount of producer biomass that can be consumed by primary consumers is higher than the primary consumer biomass in the ecosystem
  • Similarly the total biomass of secondary consumers is lower than that of primary consumers
  • The higher to the top of the pyramid, the less the amount of biomass per unit area

Pyramid of energy:

  • The source of energy in an ecosystem is light energy from the sun that is absorbed by green plants to carry out photosynthesis and convert it into chemical energy.
  • Energy will be transferred to the next trophy level when the primary consumer consumes the producer plant
  • The energy present in food molecules may be stored in body tissues or transferred to the environment in the form of excrement such as urine or excreted through feces.
  • When food molecules are broken down for respiration and other reactions, some energy is released into the environment through heat. Only a small portion of the energy in food is converted to energy stored in body tissues as a supplement to the organism's biomass.
  • Only 10% of the energy is transferred to the next trophy
  • 90% of energy is lost to the environment through heat, life processes, excretion and decontamination
  • Therefore, organisms at lower trophic levels have more available energy content than organisms at higher trophic levels.
 

Types of interaction among biotic components:

  • Saprophytism
  • Symbiosis
 

Saprophytism:

  • Interactions of organisms that obtain food from dead organic matter
  • For example, mushrooms that grow on dead trees

Symbiosis:

  • Symbiosis occurs when different species live together and interact with each other.
  • Mutualism
  • Commensalism
  • Parasitism

Predation:

  • Involves one organism (predator) eating another organism (prey)

Competition:

  • Occurs when organisms in one habitat compete for basic needs
 

Mnagrove ecosystem:

  • Abiotic components
  • Biotic components
 

Abiotuc components of mangrove ecosystems:

  • Exposed to waves and tides
  • Soft, slippery, muddy and poorly ventilated soil
  • Exposed to strong winds
  • High salt content in the soil and very low concentration of dissolved oxygen in the water
  • Exposed to high light intensity
  • Seed germination in tidal areas
 

Biotic components:

  • Stork
  • Mushroom
  • Mangrove trees
  • Crab
  • Mudskipper
  • Snake
  • Proboscis monkey
 
Adaptations features of the mangrove trees:
 
Parts of mangrove trees Adaptations features
Leaves
  • Mangrove trees have thick cuticle leaves and embedded stomas that can reduce the rate of transpiration.
  • Mangrove trees also have succulent leaves that can store water and have a special structure known as a hydatode to get rid of excess salt.
  • Older leaves can store salt and will fall off when the concentration of stored salt is too much.
Pneumatophere roots
  • Pneumatophore roots are short root projections from the soil surface for aeration in areas that are often inundated with water.
  • These roots help gas exchange between the submerged roots with the atmosphere through the lenticels.
  • Example: Avicennia sp.
Prop roots
  • Prop roots grows branching from the bottom of the trunk of a mangrove tree.
  • These roots grip in the soil strongly to provide support against strong winds and waves.
  • Example: Rhizophora sp.
Buttress roots
  • Buttress root is a type of root with a thickened flake structure to increase the surface area of the base.
  • These roots support trees that grow on soft soil bordering the land.
  • Example: Bruguiera sp.
Seeds
  • Viviparous seeds germinate and grow while still attached to the parent tree.
  • This allows the seeds to fall strewn on the muddy ground and not be washed away by the waves.
 

Collonisation and succession:

  • Collonisation: plants start to conquer an uninhabited area,breed and form colonies in that area
  • Succession: a few species of dominant plants in a habitat are gardually being replaced by other species called successor
 

Coastal zone:

  • The coastline zone is most vulnerable to large waves.
  • This zone is overgrown by a pioneer species, namely the Avicennia sp. (fire-tree) and Sonneratia sp. (perepat tree).
  • The extensive root system and pneumatophores help the tree trap mud and organic matter carried by the tide.
  • This leads to a gradual accumulation of mud. As a result, the soil becomes higher and denser.
  • Rhizophora sp. displacing and replacing pioneer species

Middle zone:

  • The central zone is located along the river near the estuary.
  • Grown by Rhizophora sp. (oil mangrove tree) which has tangled tap roots that can trap tree twigs and mud that drift and block the flow of water.
  • Mud trapping causes sedimentation to occur more rapidly.
  • The cliffs become higher and drier due to less overflow of sea water during high tide.
  • The soil became less suitable for the growth of Rhizophora sp.,
  • On the other hand more suitable for Bruguiera sp.
  • Bruguiera sp. displacing and replacing Rhizophora sp.

Inland zone:

  • The inland zone is located far inland.
  • The ground becomes higher, harder and only flooded with seawater during high tide.
  • Grown by the tree Bruguiera sp. (red tumu) which has banir roots to trap more mud and silt.
  • The sedimentation process forms new swamps that project into the sea.
  • The old beach is getting further and further away from the sea.
  • The soil on the coast turns to terrestrial and is suitable for terrestrial trees such as Nypa fruticans and Pandanus sp.
  • Terrestrial trees displace and replace Bruguiera sp.
 

The importance of the mangrove ecosystem:

Protection zone:

  • Mangrove swamps serve as a natural buffer to reduce the speed of waves and winds that reach the coastal areas.
  • The mangrove swamp forest is a refuge for small fish, shrimp and crabs from predators and the movement of water currents and strong waves.
  • Mangrove swamps serve as sanctuaries and food sources for various species of migrating birds.

Fishery resources:

  • Seafood such as fish, shrimp, crabs and snails are a source of income for fishermen in mangrove swamps.
  • The waters in the mangrove swamps support the floating cage industry to breed commercial species.

Forestry resources:

  • Mangrove wood can be used to make canoes, fish traps and building frames.
  • Mangrove wood can also be used to make handicraft items.
  • Mangrove wood is burned in a furnace to produce a source of fuel, namely charcoal.

Food and medicine resources:

  • Fruit of Avicennia sp. can be eaten as a vegetable.
    Avicennia sp. can be boiled and eaten, while the flowers produce honey.
  • Fruit Sonneratia sp. used in the manufacture of beverage ingredients.
  • Fruit of Nypa sp. edible and the water from its fruit can be used in the manufacture of vinegar and nira.
  • Bark of Bruguiera sp. used to treat diarrhea.