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Question

Difficulty: MediumEcological Functions, Nutrient Cycles and Ecological Succession

Which of the following statements regarding biogeochemical cycles and ecological succession are correct?

  1. In gaseous biogeochemical cycles, the primary reservoir pool is located in the atmosphere or the hydrosphere.Answer
  2. B
    Primary ecological succession progresses at a significantly faster rate than secondary ecological succession.
  3. The phosphorus cycle is a sedimentary nutrient cycle whose primary reservoir is mineral rock deposits.Answer
  4. D
    Both hydrarch and xerarch succession ultimately lead to an unstable, rapidly changing pioneer community.

Answer

The correct statements are: 'In gaseous biogeochemical cycles, the primary reservoir pool is located in the atmosphere or the hydrosphere' and 'The phosphorus cycle is a sedimentary nutrient cycle whose primary reservoir is mineral rock deposits'.
The statements confirming that gaseous cycles have their reservoir pools in the atmosphere or hydrosphere and that the phosphorus cycle is a sedimentary cycle with reservoir in rocks are both factually accurate. Biogeochemical cycles are broadly divided into gaseous (atmosphere/hydrosphere reservoir) and sedimentary (lithosphere reservoir) types.

Step-by-Step Solution

1
Analyze biogeochemical nutrient cycle categories
Gaseous cycles have reservoir pools in the atmosphere/hydrosphere (e.g., nitrogen, carbon), whereas sedimentary cycles have reservoir pools in the lithosphere/rocks (e.g., phosphorus, sulfur).
Correctly distinguishing gaseous and sedimentary cycles establishes the truth of the statements regarding reservoir pools.
2
Evaluate the rates of ecological succession types
Primary succession begins on newly exposed surfaces lacking soil (e.g., bare rock, lava flow), requiring centuries to build soil. Secondary succession occurs where natural vegetation was destroyed but soil remains intact, progressing much faster.
This shows that claiming primary succession is faster than secondary succession is scientifically inaccurate.
3
Determine the endpoint of ecological succession pathways
Both hydrarch (starting in water) and xerarch (starting on dry land) successions converge toward medium moisture (mesic) conditions represented by a stable climax community.
Succession leads toward equilibrium climax communities rather than unstable pioneer communities.

Key Concept

Classification of Biogeochemical Cycles and Dynamics of Primary vs. Secondary Ecological Succession
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Topics

Ecological Functions, Nutrient Cycles and Ecological Succession