Ecology – Study Notes for Manipur PSC
(General Awareness & Current Affairs)
Target Exam: Manipur Public Service Commission (PSC)
Section: General Awareness – Current Affairs
Topic: Ecology
1. Simple Explanation
Ecology is the scientific study of relationships between living organisms and their environment – both biotic (living) and abiotic (non‑living). It helps us understand how ecosystems function, how species interact, and how human activities influence the natural world.
Key ideas:
- Ecological systems are continuous, not isolated.
- Energy flow and nutrient cycling keep ecosystems alive.
- Biodiversity (species, genetic, ecosystem diversity) is vital for resilience.
2. Key Points
| Aspect | Details |
|---|---|
| Levels of Organization | Organism → Population → Community → Ecosystem → Biosphere |
| Ecosystems in Manipur | <ul><li>Sub‑tropical evergreen forests</li><li>Hill & valley ecosystems (Zeme, Chandel, Senapati districts)</li><li>Wetlands (e.g., Loktak Lake, Imphal Valley wetlands)</li></ul> |
| Biological Diversity (Biodiversity) | • 20,000+ plant species reported in Manipur. • 1,500+ bird species; 270+ mammal species (e.g., hoolock gibbon, hoolock gibbon). • 250+ reptile and amphibian species. |
| Key Ecological Concepts | • Succession – natural progression from pioneer species to climax community. • Food Chains & Webs – producers → primary consumers → secondary consumers → apex predators. • Nutrient Cycling – carbon, nitrogen, phosphorus cycles. |
| Human Impact | • Deforestation & illegal logging. • Rapid urbanization of Imphal and Thangmeiband. • Climate change effects – altered rainfall patterns, glacial melt. |
| Conservation Initiatives | • Manipur Biodiversity Conservation Program (MBCP) – focuses on species protection and habitat restoration. • Loktak Lake Protection Act – regulates fishing, boating, and tourism. • Community Forest Management – local groups manage forest resources. |
| Recent Ecological Events (2023‑24) | • Loktak Lake water level rise – leading to submergence of surrounding villages. • Discovery of new amphibian species in Chandel district (2024). • Implementation of “Tree‑Planting Campaign” – 2 million saplings planted in 2024 across Manipur. |
| Important Ecological Terms | • Habitat – natural home of a species. • Niche – role of a species in its ecosystem. • Keystone species – species with disproportionately large effect (e.g., elephants in forest). • Eutrophication – nutrient enrichment causing algal blooms. |
3. Worked Example
Problem:
A forest researcher recorded the following bird species counts in a 1 km² plot in the Chandel district:
| Species | Count |
|---|---|
| Bulbul | 12 |
| Pigeon | 8 |
| Jay | 5 |
| Sparrow | 20 |
| Parrot | 4 |
- Calculate the Species Richness (S).
- Compute the Shannon Diversity Index (H′).
- Interpret the results.
Step‑by‑Step Solution
1. Species Richness (S)
Number of distinct species observed.
( S = 5 ) (Bulbul, Pigeon, Jay, Sparrow, Parrot)
2. Shannon Diversity Index (H′)
Formula:
[
H' = -\sum_{i=1}^{S} p_i \ln(p_i)
]
where ( p_i ) = proportion of individuals belonging to species i.
Total individuals: (N = 12+8+5+20+4 = 49)
| Species | Count | (p_i = \frac{count}{N}) | (p_i \ln(p_i)) |
|---|---|---|---|
| Bulbul | 12 | (12/49 = 0.245) | (0.245 \times \ln 0.245 = -0.363) |
| Pigeon | 8 | (8/49 = 0.163) | (0.163 \times \ln 0.163 = -0.324) |
| Jay | 5 | (5/49 = 0.102) | (0.102 \times \ln 0.102 = -0.229) |
| Sparrow | 20 | (20/49 = 0.408) | (0.408 \times \ln 0.408 = -0.384) |
| Parrot | 4 | (4/49 = 0.082) | (0.082 \times \ln 0.082 = -0.188) |
Sum of (p_i \ln(p_i)):
(-0.363 - 0.324 - 0.229 - 0.384 - 0.188 = -1.488)
Hence,
[
H' = -(-1.488) = 1.488
]
3. Interpretation
- Species Richness (S=5): Indicates moderate variety.
- Shannon Index (H′≈1.49): Moderate diversity (values range from 0 to ~3–4).
- A high (H') would suggest even distribution among species; here, Sparrow dominates (20/49 ≈ 41 %).
Conclusion:
The plot exhibits moderate species richness but a skewed abundance, with Sparrow being the most common species