Manas Tiger Reserve loses 44% grassland to invasive species – Implications for rhinos and biodiversity
Manas Tiger Reserve in Assam has lost over 43% of its grassland between 1990 and 2019 due to invasive alien plants, reduced herbivore grazing, fires and encroachment. The decline threatens grassland‑dependent species such as the Indian rhinoceros and highlights challenges in biodiversity conservation for UPSC aspirants.
Overview Over the past three decades, the Manas Tiger Reserve has seen a sharp decline in its grassland cover. In 1990, grasslands occupied 53.61% of the reserve; by 2019 they fell to 30.24%, a loss of 43.59% (23.37% absolute area). The decline threatens species that depend on open habitats, such as the Indian rhinoceros , pygmy hog, and hispid hare. Key Developments Fourteen invasive alien plant species, including Chromolaena odorata and Lantana camara , have spread, converting grasslands into woodlands. Large herbivore numbers fell due to poaching and civil unrest (1988‑2004), reducing natural grazing pressure. Uncontrolled forest fires and indiscriminate livestock grazing further degraded habitats. Woodland area rose from 40.42% (1990) to 60.62% (2019), accelerating succession. Encroachment of 3,709 hectares in core zones has been recorded since the 1980s. Important Facts Reserve area: 2,837.31 sq. km ; core tiger habitat: 526.22 sq. km . Grassland loss: 43.59% relative, 23.37% absolute . Invasive species list: Chromolaena odorata, Mikania micrantha, Lantana camara, Leea asiatica, Bombax ceiba, Dillenia pentagyna . Manas shares a border with Bhutan’s Royal Manas National Park (1,057 sq. km, elevation 80‑2,707 m). Management authority: BTC Forest Department. UNESCO status: UNESCO World Heritage Site since 1985. UPSC Relevance The case illustrates several themes in the UPSC syllabus: (i) environmental governance – role of state agencies and community bodies in managing protected areas (GS3); (ii) invasive species management – ecological impact of non‑native flora on biodiversity (GS3); (iii) human‑wildlife conflict and the effect of civil unrest on conservation (GS3); (iv) policy implementation challenges in remote, conflict‑prone regions (GS2). Understanding these links helps answer questions on biodiv
Quick Reference
Key Insight
Grassland loss in Manas threatens rhinos and tests India’s invasive‑species policy.
Key Facts
- घासभूमि आवरण 53.61% (1990) से 30.24% (2019) तक गिर गया – 43.59% सापेक्ष हानि (23.37% निरपेक्ष क्षेत्र)।
- चौदह आक्रमणकारी विदेशी पौधे, विशेष रूप से Chromolaena odorata और Lantana camara, ने घासभूमियों को वुडलैंड में बदल दिया।
- वुडलैंड क्षेत्र 40.42% (1990) से 60.62% (2019) तक बढ़ा।
- Manas में कोर बाघ आवास 526.22 sq. km है, कुल आरक्षित क्षेत्र 2,837.31 sq. km के भीतर।
- 1980 के दशक से कोर ज़ोन में 3,709 हेक्टेयर का अतिक्रमण दर्ज किया गया है।
- Manas एक UNESCO World Heritage Site है (1985 से) और इसे Bodoland Territorial Council Forest Department द्वारा प्रबंधित किया जाता है।
- Invasive Species (Regulation) Act विदेशी वनस्पति की प्रारंभिक पहचान और नियंत्रण के लिए कानूनी ढांचा प्रदान करता है।
Background
The decline of grasslands in Manas illustrates how invasive species, fire and loss of natural grazers can degrade biodiversity. It links to GS‑3 topics on ecosystem health, protected‑area governance and the effectiveness of environmental statutes such as the Invasive Species (Regulation) Act.
UPSC Syllabus
- Prelims_GS — Ecology and Biodiversity
- GS3 — Biodiversity and its Conservation
Mains Angle
In a GS‑3 answer, discuss the ecological impact of invasive plants in Manas and evaluate policy measures needed for grassland restoration. A possible question could ask about challenges in managing invasive species in protected areas.