Identify the ecologist from the given hints
(i) He carried out long term ecosystem experiments using outdoor plots
(ii) In his experiments he showed that "increased diversity contributed to higher productivity".

Options

A. Ahmed Khan
B. David Tilman
C. Stanley Cohen
D. Ernst Chain

Answer

**Step-by-Step Solution:**

1. **Understanding the Hints**: The question provides two specific hints about an ecologist. The first hint indicates that this ecologist conducted long-term ecosystem experiments using outdoor plots. The second hint states that he demonstrated that increased diversity contributes to higher productivity.

2. **Identifying the Ecologist**: Based on the hints, we need to identify an ecologist known for conducting outdoor ecosystem experiments and for linking biodiversity to productivity.

3. **Recalling Relevant Ecologists**: One prominent ecologist who is well-known for such studies is David Tilman. He is recognized for his long-term experiments in grassland ecosystems, where he manipulated species diversity and observed its effects on productivity.

4. **Analyzing David Tilman's Work**: In his experiments, Tilman found that plots with greater species diversity exhibited higher productivity and stability. He showed that these diverse ecosystems had less year-to-year variation in biomass, making them more resilient to disturbances and less susceptible to invasions by non-native species.

5. **Conclusion**: Based on the analysis of the hints and the relevant work of ecologists, the answer to the question is David Tilman.

**Final Answer**: David Tilman

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