Final answer:
A student should focus on communities established on new land or exposed substrates, which are characterized by initial colonization by pioneer species, and ultimately lead to more complex ecosystems.
Step-by-step explanation:
A student studying primary succession should focus on communities that are established on newly formed or exposed land, where no soil or life previously existed. This process begins with pioneer species, which are capable of colonizing the bare substrate, thereby initiating the creation of new soil and paving the way for other species to follow. An example of such a community can be found in areas of Hawaii where volcanic activity results in the eruption of lava onto the ocean floor, consequently leading to the formation of new land. As the lava hardens and weathers, pioneer species, such as certain lichens and succulent plants, establish themselves on the barren rock. Over time, more complex species take root and a mature community known as the climax community develops.