Grassland Ecology

Definition

• Grassland ecology is the study of structure, composition, distribution, productivity, and functioning of grass-dominated ecosystems, along with their interaction with environment, grazing animals, and human activities.
• It includes the management, conservation, and utilization of natural and cultivated grasslands.

Extent of Grasslands

• Grasslands cover ~40% of Earth’s terrestrial area.
• In India → ~45% of geographical area is under some form of grazing (forests, permanent pastures, wastelands).
• Permanent pastures & grazing land in India: ~12 Mha only (<4% of TGA).

Types of Grasslands in India

(According to Dabadghao & Shankarnarayan, 1973)

• Sehima–Dichanthium type; Central India (Madhya Pradesh, Maharashtra, Chhattisgarh). Dominant spp.: Sehima nervosum, Dichanthium annulatum.
• Dichanthium–Cenchrus–Lasiurus type; Arid & semi-arid (Rajasthan, Gujarat, Haryana, Western U.P.). Dominant spp.: Dichanthium annulatum, Cenchrus ciliaris, Lasiurus sindicus.
• Phragmites–Saccharum–Imperata type; Humid regions, river basins, Terai belt (U.P., Bihar, Assam, W. Bengal). Dominant spp.: Saccharum spontaneum, Imperata cylindrica, Phragmites karka.
• Themeda–Arundinella type; Himalayan foothills (Shivaliks, N-E India). Dominant spp.: Themeda triandra, Arundinella spp.
• Temperate–Alpine grasslands; High-altitude Himalayas (J&K, Himachal, Uttarakhand). Dominant spp.: Festuca, Agrostis, Poa, Danthonia.

Ecological Importance

• Soil conservation → roots bind soil, prevent erosion.
• Water conservation → enhance infiltration, reduce runoff.
• Carbon sequestration → grasslands store ~34% of global terrestrial carbon.
• Biodiversity → habitat for birds, insects, wild herbivores.
• Climate regulation → regulate local temperature and water cycle.

Role in Livestock Economy

• About 80% of cattle feed in India comes from grasslands & fodder.
• India has ~20% of world’s livestock but only 2% of global grazing land → severe pressure on resources.
• Productivity of Indian grasslands is very low (1–2 t DM/ha/year).

Problems of Indian Grasslands

• Overgrazing → degradation, invasion of weeds (e.g., Lantana camara, Parthenium hysterophorus).
• Deforestation & cultivation → shrinkage of grazing areas.
• Shortage of fodder →
  • 35% deficit in green fodder,
  • 10% deficit in dry fodder,
  • 35% deficit in concentrates (IGFRI).
• Soil erosion & desertification in arid zones.

Grassland Improvement & Management

• Controlled grazing (rotational grazing, deferred grazing).
• Reseeding with improved grasses & legumes (Cenchrus, Stylosanthes, Clitoria).
• Silvi-pastoral systems → trees + grasses.
• Soil and water conservation → contour bunding, trenching.
• Fertilization & irrigation for productivity enhancement.
• Weed management → uprooting invasive species.

Key Facts for ASRB NET

• Grasslands = “Ocean of grasses”, cover ~40% of world land.
• Indian grassland classification: Dabadghao & Shankarnarayan (1973).
• Apex research institute: IGFRI (Indian Grassland & Fodder Research Institute), Jhansi.
• Indian grassland productivity = 1–2 t/ha/year (very low vs global average 5–6 t/ha).
• Carbon storage: Grasslands are the third largest carbon sink after forests & oceans.