Scientists interested in knowing the best way to restore an area after a temporary road was built through it completed a study comparing two treatments: (1) restoring the contour of an area so that there was no longer a depression or cut-through where the road was previously and (2) simply abandoning the area to allow vegetation to return on its own. They wanted to know whether either or both of these treatments would return the above ground vegetation and the below ground soil properties to their original state, as seen in a similar area where there has never been a road. This study was focused on which level of life's hierarchy?A. OrganismB. CommunityC. PopulationD. Ecosystem

This study was focused on an Ecosystem level, as it involved soil properties and above-ground vegetation interacting with mentioned soil physic properties.

Explanation:

Ecological studies can be performed at different hierarchy levels:

- Organism: This is an individual physiologically independent from other individuals. At this level, it must be understood how an organism survives under certain changing physic and chemistry conditions, and how it behaves to reproduce, avoid predators, and find food.

- Population: Groups of individuals from the same species, with similar characteristics, capable of crossing, leaving offspring that live in the same habitat at the same time. At this level, it is interesting to know the size of the population required to leave fertile offspring that ensure the population will survive over time. It is also interesting to know genetic variability that allows evolutive adaptation to environmental changes.

- Community: Relationship or interaction between different species groups that live in the same habitat and at the same time. At this level, it is interesting to study inter-specific interactions that could cause changes in the populations´ size. These could be the cases of competition, predation, parasitism, mutualism, and etcetera.

- Ecosystem: Basic interaction unit between population and environment that turn in complex relations existing between living and non-living elements in a given area. In the example, interactions between recovering vegetation and soil properties, as non-living elements.