The correct option is 2 only
Explanation
Ecosystem functions refer to the biological, geochemical, and physical processes that take place within an ecosystem. These include energy flow, nutrient cycling (biogeochemical cycles), and ecological succession. While energy flow is unidirectional, the movement of nutrients is cyclic.
Statement-wise Analysis:
- Statement 1 is Incorrect: Ecosystem services are the products of ecosystem processes. Forests play a critical role in these services by purifying air and water, mitigating droughts and floods, and cycling nutrients. These are often categorized as regulating services.
- Statement 2 is Correct: Unlike energy, which flows unidirectionally and dissipates as heat, nutrients move in cycles. Nutrient cycling (biogeochemical cycling) involves the movement of nutrient elements through the various components of an ecosystem. Nutrients are never lost from the ecosystem; they are recycled repeatedly between the biotic (living) and abiotic (non-living) components.
- Statement 3 is Incorrect: Nutrient cycles are classified based on the location of their reservoir:
- Gaseous Cycles: The reservoir is the atmosphere or hydrosphere (e.g., Nitrogen and Carbon cycles).
- Sedimentary Cycles: The reservoir is the Earth's crust or lithosphere (e.g., Phosphorus and Sulphur cycles). Therefore, the atmosphere is not the main reservoir for sedimentary cycles.
Key Takeaway:
Energy flow in an ecosystem is unidirectional and non-cyclic, whereas nutrient movement is cyclic (biogeochemical cycles). Sedimentary cycles rely on the Earth's crust as a reservoir, while gaseous cycles rely on the atmosphere or hydrosphere.