Researching unaltered ecosystems helps scientists in many ways. There is a lot of Methodology and very precise data that needs to be collected, but I'll just try to gloss over the main points.
Questions on landscape ecology, behavioral ecology, ecosystem dynamics, community ecology and nutrient cycling are reviewed in the process. But this helps scientists with figuring out with what issues need to be solved and how the modern world affects these unaltered ecosystems. It can also help scientists possibly find new forms of life, even to the microscopic level since the ecosystem is unaltered. Finally, it also helps track animal movements if that data is needed.
Hope this helps! Feel free to message me if you need more help or if oyu have any questions! :)