State the way in which increasing species diversity can affect the ecosystem

The correct option is: it increases the productivity and efficiency of an ecosystem.

Increasing species diversity has a positive impact on the functioning of an ecosystem due to several key ecological principles:
1. Niche Complementarity: Different species have unique traits, root depths, feeding habits, and resource requirements. In a diverse ecosystem, species utilize different portions of the available resources (like nutrients, water, and sunlight) rather than competing for the exact same pool. This leads to a more thorough and efficient overall use of resources within the environment.
2. Functional Redundancy and Stability: A diverse ecosystem contains multiple species that can perform similar ecological roles. If environmental changes or disturbances affect one species, other species can step in and maintain the ecosystem's processes, ensuring that efficiency does not drop.
3. Higher Biomass Production: Because resources are captured and utilized more efficiently by a diverse group of organisms, the overall rate of energy conversion and biomass accumulation (productivity) of the ecosystem is significantly higher compared to monocultures or low-diversity systems.

Therefore, higher species diversity leads to a more productive and resource-efficient ecosystem.