The field studies collect data from two types of sites. A local, easily available field site is the primary place information is gathered by student visits. It is far from an optimal place to do ecological studies. For example, it has a history of manipulation and its plants are mostly weedy species. The local-site limitations are overcome by having several highly instrumented alternative sites.
Interpretations involve comparisons between the intensive and extensive sites.
Because the extensive sites are monitored with remote instrumentation, they can be optimal even if they are not very accessible.