Natural Vegetation and Wildlife Class 9 Notes — Geography Chapter 5

Factors Affecting Biodiversity and Natural Vegetation

India's massive bio-diversity is governed by two main physical factors: Relief and Climate.

1. Relief Factors:

• Land: The nature of land affects the type of vegetation directly. Fertile, level land is generally devoted to agriculture, whereas undulating and rough terrains develop grasslands and woodlands, providing shelter to diverse wildlife.
• Soil: Different types of soil support different kinds of flora. Sandy soils of the desert support cactus and thorny bushes; wet, marshy, deltaic soils support mangroves, and hill slopes with deep soil support conical trees.

1. Climatic Factors:

• Temperature: The character and extent of vegetation are mainly determined by temperature along with humidity, precipitation, and soil. On mountain slopes above 915 meters, the fall in temperature affects vegetation types, changing them from tropical to subtropical, temperate, and alpine.
• Photoperiod (Sunlight): The variation in the duration of sunlight at different places depends on latitude, altitude, and season. Trees grow faster in summer due to longer photoperiods.
• Precipitation: In India, almost the entire rainfall is brought in by the advancing southwest monsoon and retreating northeast monsoons. Areas of heavy rainfall have denser vegetation compared to areas of low rainfall.

Comparison of Major Forest Types in India

Essential Exam Glossary

Natural Vegetation

A plant community that has grown naturally without human aid and has been left undisturbed by humans for a long time.

Virgin Vegetation

Natural vegetation that has remained completely undisturbed by humans for a long time.

Endemic Species

Purely native plant or animal species belonging exclusively to a specific country or region.

Exotic Species

Species of plants or animals that have been introduced to a region from outside its native geographic boundary.

Flora

The plant life occurring in a particular region or time, generally the natural native plant species.

Fauna

The animal life occurring in a particular region or geological period.

Biome

A very large ecosystem on land having distinct types of vegetation and animal life, defined by its climatic conditions.

Must-Remember Key Revision Points

• India is one of the 12 mega bio-diversity countries of the world, boasting around 47,000 plant species.
• India ranks tenth in the world and fourth in Asia in plant diversity.
• There are approximately 15,000 flowering plants in India, accounting for 6% of the world's total flowering plants.
• The country has about 90,000 species of animals, as well as a rich variety of fish in its fresh and marine waters.
• Ecosystem stability: All plants and animals in an area are interdependent and interrelated in their physical environment, forming an ecosystem.
• Human Impact: Humans disrupt ecosystems through clearing land, hunting, and pollution, causing many species to become endangered or extinct.
• Wildlife Protection Act (1972): Implemented in India to provide a legal framework for protecting wild animals and plant species.
• Government Conservation Initiatives: Setting up of Biosphere Reserves (e.g., Sundarbans, Gulf of Mannar, Nilgiri), Project Tiger, Project Elephant, and Project Great Indian Bustard.

Examples of Ecosystem Conservation & Distribution

• {"title":"Example 1: Wildlife Adaptations in Extreme Climates","description":"In the freezing high altitudes of Ladakh, animals like the Yak (shaggy-horned wild ox), the Tibetan antelope, Bharal (blue sheep), and Kiang (Tibetan wild ass) have adapted with thick coats of fur to survive extreme sub-zero temperatures."}
• {"title":"Example 2: Deltaic Ecosystems (Mangroves)","description":"The Ganga-Brahmaputra Delta is famous for the Sundari trees, which provide strong, durable timber. This delta is also the home of the world-famous Royal Bengal Tiger."}

Exam Traps & Board Cues

1. Distinction Questions: High-scoring 3-mark or 5-mark questions frequently ask for the difference between Tropical Evergreen Forests and Tropical Deciduous Forests. Always structure your answer with direct corresponding points (Rainfall, Leaf-shedding cycle, Common Trees, and Regional location).
2. Map Work Warning: Be prepared to locate major National Parks (such as Kaziranga, Manas, Corbett, Shivpuri, Simlipal) and Wildlife Sanctuaries on the political map of India. This is a guaranteed scoring section.
3. Rainfall Boundaries: Do not mix up the rainfall figures! Remember: Evergreen is >200 cm, Deciduous is 70 cm to 200 cm, and Thorn Forests are <70 cm.

Practice Questions with Solutions

• What is the difference between Endemic and Exotic species? Endemic species are native species that belong naturally and exclusively to a country/region (e.g., Indian wild ass). Exotic species are introduced from outside the country (e.g., Water Hyacinth).
• Why do trees grow faster in summer? In summer, the duration of sunlight (photoperiod) is longer, which accelerates the process of photosynthesis in plants, resulting in faster growth.
• Name two major biosphere reserves of India that are part of the World Network of Biosphere Reserves. The Sundarbans in West Bengal and the Gulf of Mannar in Tamil Nadu.
• Why are thorn forests found in northwestern parts of India? The northwestern part of India receives less than 70 cm of annual rainfall. The semi-arid climate and dry sandy soils naturally support plants like cacti and acacias that can survive with minimal moisture.

Frequently Asked Questions