Ecology BIO C 322 Ecosystems Concept Structure Ecosphere

Ecology (BIO C 322) Ecosystems: Concept & Structure

Ecosphere Biome The Ecological Hierarchy Ecosystem Community Population Organism Organ system organ tissue cell

Ecosystem: Living Beings Interacting with Abiotic Factors

Ecosystem • Biotic community interacting with the physical environment. • Cycling of materials. • First complete unit in ecological hierarchy. • Unity of organisms & environment. • Boundaries natural or arbitrary.

• Open systems Importance of input & output environments. • Sun the ultimate source of energy. • Other sources? • Three basic ecosystem components: – Community; – Energy flow (non-cyclic); utilized + heat; – Nutrient flow (cyclic).

Ecosystem’s Dependence on Environment • Size of system: Larger, less dependence. • Metabolic rate: Higher, more dependence. • Autotrophic-heterotrophic balance: Greater imbalance, more dependence. • Stage of development: Younger, more dep. • e. g. Himalayas vs Bangalore

Trophic Structure of Ecosystem • Autotrophic stratum: Green belt Fixation of light energy. • Heterotrophic/phagotrophic stratum: Brown belt Accumulation & decomposition of organic matter (by saprotrophs/microconsumers). • Products of decomposition: Particulate OM, Dissolved OM, Volatile OM.

What makes the Earth’s ecosystems habitable?

Comparative Atmospheres of Mars, Earth and Venus: High O 2 (21%) & low CO 2 (0. 03%) levels on Earth; High CO 2 (95%) & low O 2 levels (Traces) on Mars & Venus.

Practice Concept • The atmosphere of Earth did not just develop by a chance interaction of physical forces into a lifesustaining and self-regulating condition, and then life evolved to adapt to this condition. Rather, organisms from the very beginning played a major role in the development and control of a geochemical environment favourable to themselves…It is the microorganism web of life operating in the brown belt as an intricate control system that functions to maintain a pulsing, homeorhetic balance.

Gaia Hypothesis • Goddess Earth in ancient Greece. • Proposed by James Lovelock. • Organisms not only adapt themselves, but also change the environment to suit their biological needs.

A Ring-shaped Coral Reef called Atoll in Pacific Ocean: Formed by Ca. CO 3 Secretion by corals (Sea Animals); Support a Great Variety of Animal and Plant Life.

Restoration Ecology • Humans modify their env beyond restoration to suit immediate needs Global climate change. • Restoration ecology: Recovery of ecosystems damaged by pollution or invasion of exotic species. • Restoration by natural processes time-taking. • Prevention vs cure.

Examples of Restoration Ecology • Restoration of nitrogen-poor soil: Application of artificial/organic fertilizers (short-term) or introduction of N-fixing plants (long-term). – Acacia tree plantation on coal mine waste areas in India.

• Revegetation: Encouraging immigration of seed carriers, especially birds.

• Phytoremediation: Accumulation of metals (Zn, Ni, Pb, Cu) in harvestable biomass Incineration Recovery of metals in ash. – Brassica juncea (Indian mustard) used for Pb removal.

Agroecosystems • Differ from natural ecosystems: – Solar energy supported by labour, fertilizers, pesticides, irrigation water; – Plants/animals artificially selected. • Costs: – Soil erosion; – Pollution (fertilizers, pesticides); – Reduced biodiversity; – Increased vulnerability to weather changes, pests.

Types of Agriculture • Pastoralism: People herding cattle in arid/semiarid regions of low rain (grasslands of Africa), high altitudes; living on animal products (milk/meat). • Shifting agriculture (slash-and-burn): Forests cut, debris burned Cultivation of crops for some years till nutrients used up Move on, forest regrowth (Tropical regions/Asia). • Flood irrigation: Along rivers, fertile deltas; most productive.

• Pre-industrial: Provide food for limited population, self-sufficient, use of labour.

• Industrial: Mechanized, use of fertilizers & pesticides pollution, soil erosion, habitat loss. • Low Input Sustainable Agriculture (LISA): Sustaining crop yields (profits), while reducing inputs of fertilizers, pesticides, fossil fuels.

Indian Perspective

• Creation of homogenous crop varieties (reduced diversity). • These perform well only if supplied with large amounts of water, fertilizers, pesticides. • Such practices followed for cereal crops (wheat, rice); legumes ignored. • Result: Scarcity of pulses Price rise Protein deprivation for poor.

Diversity Matters • Thousands of years of Indian agricultural practices Tremendous genetic diversity. • Much of India’s crop diversity preserved in agricultural research stations in India & seed banks owned by foreign commercial companies.

- A few years ago, rice crop in SE Asia infected by brown leaf hopper insect. - Solution: Gene (insect-resistance) in rice variety from Pattambi (Kerala) in a collection at Int. Rice Research Institute in Philippines. - The gene incorporated into high yielding variety by classical breeding techniques. • MNCs see commercial potential Biotechnological production & sale of new varieties incorporating imp. genes.

Gradients • Zonation of physical factors. • e. g. Temperature gradient from poles to Tropics. • e. g. Thermal stratification in temperate lakes. • Generally, environmental conditions & adapted organisms change gradually along a gradient.

Vegetation based Gradients or Zonation On Land (With Respect to Altitude)

Ecotone or Edge Habitat or Interface zone: Transition Zone between Ecosystems. e. g. Sea beaches, mangrove forests, coral reefs (land-sea ecotones).

Ecotone characterized by Increased Biodiversity (Edge Effect) • Unique Species Inhabiting Edge Habitats: Edge Species. • Human activities Edge sharpening Poor diversity (Uncut vs clear forest).

Biodiversity: Species Richness (No. of Species in ecosystem); Relative Abundance or apportionment (No. of Individuals in each species.

Two Ecosystems may have same Richness, but differ in Relative Abundance of Constituent Species

Biodiversity of India • One of the top 12 countries in terms of biodiversity. • Great productivity; year-round occurrence of conditions favourable to life; lower level of impact of ice ages in past. • High species turnover near sea & mountains. • Endemic species found in isolated regions like Andaman, Nicobar, Lakshadweep islands. • 15, 000 species of flowering plants; 317 species of mammals; 969 species of birds; 389 species of reptiles.

Himalayas & Western Ghats very rich in biodiversity

The Making of Salim Ali (1896 -1987)

• Dr. Ali regarded one of the greatest biologists of 20 th century India. • Shot birds as a child. • Meticulous observation & recording of lives of birds Biodiversity conservation. • His magnum opus, the ten volume Handbook of the Birds of India & Pakistan. • Autobiography: The Fall of a Sparrow (1985).

Birds at Sariska National Park, Rajasthan

Practice Concept (Dr. Madhav Gadgil, IISc, Bangalore) • In India, efforts at protecting diversity have focused exclusively on large nature reserves & sanctuaries. Little thought or effort has gone into the conservation of biodiversity outside the nature reserve system. • An alternative system of biodiversity conservation, covering all of rural India, might provide a solution. Locality-specific knowledge of biodiversity elements possessed by “ecosystem people”, i. e. local & tribal populations, can be tapped to feed into a wider process of biodiversity conservation. • In turn, these people can be rewarded for protecting biodiversity by provision of funds or educational and health facilities in their locality.

SRISHTI • Organization founded by Dr. Anil Kumar Gupta, IIM, Ahmedabad. • Organized biodiversity contests in different states. • Discovery of exceptional individuals who know hundreds of local species. • Due credit given to winners.

Shannon’s Diversity Index (H): Used to Calculate Biodiversity H value varies from Zero to 4. 6 E value varies from Zero to 1