Concepts of Ecology Definition Ecology is the scientific study of interaction between living systems and their environment Objective Ecology discovers and understands the relationship between living things and their environment
More Definitions Hilaire, 1835 -Milieu ambient (French) Haeckel, 1866 – Science associated with life Elton, 1927 – Scientific natural history Shelford, 1929 – Science of communities Andrewartha, 1961 – Study of the distribution and abundance of organisms Odum, 1963 – Study of structure and functions of nature
A person who studies ecology
e.g., Plant ecologist, Animal ecologist, Terrestrial / Aquatic ecologist, Palaeo-ecologist, Mathematical ecologist, Systems ecologist, Chemical ecologist, Social ecologist, Anthropo-ecologist, Autecologist, Synecologist.
TEN RULES IN ECOLOGY
Ecology is a Science.
Ecology is only understandable in the light of evolution.
Nothing happens ‘for the good of the species’.
Genes and environment are both important.
Understanding complexity requires models.
‘ Story telling’ is dangerous.
There are hierarchies of explanations.
There are multiple constraints on organisms.
Chance is important.
10. The boundaries of physical environment are in the mind of the Ecologist.
Branches of Ecology Habitat ecology Desert ecology Grassland ecology Freshwater ecology Forest ecology Cropland ecology Marine ecology Population ecology Community ecology Ecosystem ecology Production ecology Conservation ecology Radiation ecology Palaeoecology Gene ecology Systems ecology Microbial ecology
Concept of Environment Definition
The total surrounding of an organism.
Environment is an interacting system of physical, chemical,
biological social and cultural elements.
Environmental systems usually do not have well defined boundaries.
Environmental characteristics change over a gradient.
Environmental system is open because it receives inputs from and gives outputs to other systems.
Environment ultimately determines the quality and survival of life.
Ecological System Concept (Concept of Ecosystem) Ecosystem is the basic structural and functional unit of ecology. “ Ecosystems are the basic units of nature on the face of the earth”. An ecosystem is an ecological unit, or a subdivision of the landscape, or a geographic area that is relatively homogeneous and reasonably distinct from adjacent areas. J.W. Marr, 1961 Tansley, 1935 Definition
Ecosystem – another view
Ecosystem is a spatial functional structure
The space may be geographically large or small
Largest ecosystem. e.g., Planet earth
Smallest ecosystem (microcosm):
e.g. a handful of soil and moss in a sealed jar.
Components of an Ecosystem Abiotic components- (geographical, climatic, physicochemical characteristics) B iotic components- (Plants, animals, microbes)
Interactions between Organisms and Environment
Living organisms and their non-living environment are inseparable, interrelated and interact upon each other.
Specific influence of human beings on sensitive Ecosystems Mountain ecosystem – Removal of forest cover Evergreen forests – Over exploitation of forest resources Coral reefs – Human interference, Dynamite fishing River ecosystem – Pollution Land ecosystem – Dumping solid wastes
Systems Biology A biology that sees an organism as a living system rather than a machine. Systems theory It looks at the world in terms of the interrelatedness and interdependence of all phenomena. Systems thinking is process thinking System defined A system is an object that is made up of subsystems or components, which interact in such a way that they have collectively a wholeness.
Salient features of system concept
1. There is a collection of elements (subsystems) in a system.
2. The components (subsystems) and their processes are organized.
The interactions between the subsystems are
repeated in time and space.
4. There is unidirectional flow of energy and matter.
A healthy system is self-regulating based upon
the feed-back control from subsystems.
Examples : Animal social systems – An Ant hill, a bee hive, a termite mound. Human social systems – a family.
Inputs Outputs Simple System Model System
A cybernetic system is a collection of parts or events that acts as a single thing and regulates its activities about an ideal state or set point
Cybernetic systems use feedback to maintain this ideal state.
The feedback that causes the adjustment to the set point is called negative
Cybernetic systems can also display positive feedback .
Positive feedback is a continually increasing tendency away from the system’s set point.
A system consists of a set of interdependent subsystems enclosed in a defined boundary.
A system receives inputs and outputs.
An input is any resource from outside to which the system responds.
An output is any attribute transmitted to the environment.
A system has feed back mechanism, which provides a degree of control (or homeostasis)
Positive feedback Set point Negative feedback Deficiency Excess Negative feedback Death Positive feedback Death Homeostatic Plateau A Cybernetic system of Ecosystem Regulation
Systems Concept Nutrients Gases H 2 O Radiant Energy Nutrients Gases H 2 O Bio-systems Producers consumers Decomposers (Cycling of energy and matter) Outputs Inputs
System X Y Z Subsystem X Subsystem Y Subsystem Z Inputs Outputs Open system with components
Series open system components Plant Cow Man Input Sunlight Output - Input Chemical energy in leaves Output - input Chemical energy in meat of cow Output Heat given off during
Features of an open system Open systems process inputs and produce outputs The amount of output produced is directly related to the amount of input received.
Features of Complex systems
Complex systems are composed of many interconnected and interacting subunits.
They are capable of adaptation and self-organization.
All living systems are open systems .
A cell is an open system because it constantly acquires food from outside itself and eliminates wastes.
It gives off heat as it carries on chemical processes (respiration).
Biological Systems Hierarchical System Genetic systems Cell systems Organ systems Organismic systems Population systems Ecosystems
Dynamics of ecosystems Bio-systems Energy, Gases inorganic matter water organisms Subsystems Plants animals Microbes Energy Nutrients Gases Inorganic matter Inputs Outputs
Gaseous Nutrient cycles Sedimentary nutrient cycles Biogeochemical cycles and population – Evolution spiral Outputs Heat radiated into space Inputs Sunlight (energy) The earth as a single system Earth Ecosystem
Energy flow in an Ecosystem Solar energy Photosynthesis Solar energy is converted to chemical energy Respiration Chemical energy is used to do work Ecosystem Degraded Waste Energy
Primary Production Phototrophs (Plants) – The rate of photosynthesis per unit of time. Gross Production – Quantity of organic matter produced per unit of time. Net Production – Gross P – metabolic losses (respiration, excretion) Secondary Production All biomass produced per unit of time by organisms called consumers.
Primary and Secondary Production
Primary – Rate of photo synthesis by green plants.
Secondary – The energy stored at consumer level for use.
Ecological succession Progressive changes in community structure and function. Ecosystem Regulation The ecosystem tries to resist change and maintain itself in equilibrium is called Homeostasis.
Production (Stored biomass) Gross Production Producers Photosynthetic Production Secondary Production Respiration Decomposers Consumers and Decomposers Respiration Tissue growth Relationship between plant and animal production Respiration Tissue growth
Properties of Bio-systems
It is intrinsically dynamic, flexible, open systems.
There is cyclical patterns of information flow.
The structure and function are established by the system itself (self-organising system).
It exhibits a certain degree of autonomy.
There is self-transformation and self-transcendence.
It has a high degree of stability (Homeostasis).
There is a state of continual fluctuations within limits.
It has the ability to adapt to changing environment.
It exhibits self-maintenance which includes the processes of self-renewal, healing, homeostasis and adaptation.
Functional aspects of Bio-systems
Energy cycles – Ecological pyramids
2.Food chains, food webs and trophic structure
3.Diversity of organisms – Variety and variability.
4.Nutrient cycles – biogeochemical cycle e.g. Water cycle, Carbon cycle, Oxygen cycle, Nitrogen cycle.
5. Ecosystem development and regulation.
Ecosystem goods and services Direct values Consumptive use value – Non-market value of fruits, fodder, firewood, small timber etc. (People collect them from their surrounds and use them) Productive use value – Commercial value of timber, fish, medicinal plants etc. ( People collect for sale)
Non-consumptive use value – Scientific research, watching wildlife, ecotourism, jungle safaris etc.
Option value – Maintaining options for the future – Preserving and reaping the economic benefits in the future.
Existence value – Ethical and emotional aspects of the existence of wildlife and nature.
Ecological Pyramids Pyramid of numbers : No of individuals at each trophic level Graphic representation of tropic structure and function of an ecosystem. Hawks Hyperparasites (microbes) Frogs Parasites (Lice, bugs) Insects Birds Grasses Tree s
Pyramid of biomass: Total biomass (dry matter) at each tropic level Fox Rabbit Herbs Pyramid of energy: Amount of energy present at each trophic level. Top Carnivores Carnivores Herbivores Producers
Cycling of DDT
Energy flow in an ecosystem
At every trophic level there is 90% loss of energy (respiration, activity).
Only 10% energy is transferred from one trophic level to the other.
There is one-way flow of energy.
Nutrient Cycling Nutrients like C, N, S, O, H, P etc. Move in circular paths. Hydrological cycle Nitrogen cycle Carbon cycle Phosphorous cycle
Functional Attributes Food chains The sequence of feeding relationships in an ecosystem is called food chain. Trophic structure Each organism in the ecosystem is assigned a feed level or trophic level.
Simple food web model Producer : Pond grass Herbivore : Water insects Carnivore : Large fish Herbivore : Small fish Carnivore : Duck Top Carnivore : Man
Sunlight Producer Carnivore Herbivore Heat Produced Decomposers Simple Food – Chain Model
Kinds of food chain
Grazing food chain – Starts with green plants and ends with carnivores.
Grass Rabbit Fox 2 . Detritus food chain – Starts with dead organic matter and ends with predators. Mangrove ecosystem Leaf litter Saprotrophs / detritivores (crabs) Small carnivorous fish Large Carnivorous fish - a complex inter connected network of food chains at different trophic levels. Food web
Significance of food chain
Food chains maintain energy flow and nutrient cycling.
Food chains maintain ecological balance by regulating population size.
Food chains biologically magnify toxicity of some chemicals.
Kinds of Ecosystems Ecosystem Terrestrial Aquatic Man-engineered e.g. Forest, Desert Grassland, Steppe, Savanna e.g. Agricultural land use, Urban / industrial land use Freshwater Marine Lenti c Lo t ic e.g. Ponds, Lakes e.g. Streams, Rivers Coastal ecosystems Mangrove ecosystems Seagrass ecosystems Coastal lagoon ecosystems Coral reef ecosystems Delta ecosystems Estuarine ecosystems Sandy beach ecosystems Rockyshore ecosystems Coastal upwelling ecosystems
Forest Ecosystem 1. Abiotic Component Amount of rainfall and local temperature varies according to latitude, and altitude. 2. Biotic Component Plants – trees, shrubs, climbers and ground cover. Animals – mammals, birds, reptiles amphibians, fish insects and microscopic animals.
Kinds of Forests
e.g. Himalayan region -needle –like leave forests.
Tropical rain forests
e.g. Western Ghats –broad–leaved forest.
Deciduous forests – e.g. Teak trees
Thorn forests – e.g. Semi – arid.
Mangrove forests – e.g. River deltas.
Natural forests control local climate and water regimes.
Forest vegetation helps recycle nutrients.
Forest prevent erosion of soil.
Forests control flow of water in streams and rivers.
Forests absorb carbon dioxide and release oxygen that we breathe.
Forest services - cont’d
Forests maintain gene banks of wild relatives.
Forest supply food, fodder, medicine, timber, poles and fuel wood as well as raw materials for industry.
Forests and wilderness areas are valued as sites of natural and cultural heritage as well as education and recreation.
Ecotourism is a vital source of income for some countries.
The Grassland ecosystem
Abiotic Components – C, H, O, N, P, S. are supplied by Carbon dioxide, Nitrate, Phosphates and Sulphates.