Question

Which one of the following ecological processes best explains the observation that seedling establishment increases with distance from the parent tree in a forest?

• A. Competition between species
• B. Competition within species
• C. Facilitation between species
• D. Facilitation within species

Hint:

If success increases as you move away from the parent, think \textbf{conspecific negative density dependence} (Janzen–Connell): crowding + host-specific enemies near the parent reduce survival.

Answer 1

The Correct Option is B

Seedling Establishment and Distance from Parent

Step 1: Link the pattern to classic theory.

The observation that seedlings survive better farther from the parent tree is explained by the Janzen–Connell hypothesis. Near the parent, conspecific seedlings face strong density-dependent mortality due to pathogens, herbivores, and intraspecific competition.

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Step 2: Interpret the options.

• Competition within species (conspecific): Strongest near parent where seed/seedling density is highest → survival increases with distance. ✅
• Competition between species: Cannot explain a gradient tied specifically to one species → ❌
• Facilitation: Would predict improved survival near parent/benefactor, opposite to the observation → ❌

Final Answer: \[ \boxed{\text{(B) Competition within species (conspecific negative density dependence)}} \]