This week, we narrow the focus to populations within ecosystems. Who or what populates an ecosystem, and what are their roles? How do these roles change over time? What happens when a species is removed from a system? How do scientists study the populations within an ecosystem, from its largest to its smallest inhabitants? You will explore the important roles different species can play—such as ecosystem engineers, keystone species, and indicator species—and how they shape their ecosystems.

This week we focus on community ecology and further explore the interactions between species in an ecosystem. For instance, how does the decline in a population from an ecosystem (as was the case in Gorongosa) affect the other players? How does adding a population -- such as an invasive species or translocated herds -- affect an ecosystem?

This week, we will further their understanding about what makes an ecosystem a system by examining the flow of energy and matter through different parts of the environment. This includes understanding the interactions of biotic and abiotic factors within an ecosystem and the services each component provides. We will introduce the complicated effects of both abiotic (climate change) and biotic (herbivory) interactions within a coastal salt marsh system, touching on ecological concepts of thresholds in a system and ecosystem resistance and resilience.

This week we conclude by focusing on the role of humans in ecosystems: how humans interact with and are shaped by their environments. We explore the meaning of the “anthropocene” (the title given to the current geological age in recognition of significant impact of human activities) and investigate management approaches that balance human needs and biodiversity. We also return to Gorongosa National Park to wrap up the course, shifting the conversation from "Can an ecosystem recover?" to "Should it recover?" and "What does a successful recovery look like?" We explore how conservation might have to adjust to future challenges such as climate change, extinctions, and human population growth. We also introduce the idea that a spectrum of conservation approaches is necessary, from the preservation of land and species, to the integration of biodiversity into market economies, to the creation and management of “novel” ecosystems.