Fig. 2 | Demonstration of the impact, process & response approach for a warming scenario. In this hypothetical scenario terrestrial communities (red circle) are turning over towards more warm-adapted species (aka thermophilizing) faster than freshwater communities (blue circle). The four fundamental community processes are then used within the context of our approach (Figure 1) to explain this pattern as a function of potential differences in each process between ecosystem types (see main text and Table 1).
To implement the proposed approach, we synthesize the literature to find key differences and similarities in how the four major processes operate within each system. We then use the differences and similarities we identify to infer how terrestrial and freshwater biodiversity may respond to, and recover from, these impacts. For each process, we provide non-exhaustive but representative examples of some of the major ways humans impact terrestrial and freshwater ecosystems, paying particular attention to how the process might influence the magnitude of human impacts. We also identify the physical, habitat, chemical and community properties that likely underlie differences in the strength of processes among ecosystems (Table 1). Although we focus primarily on the understudied comparison between terrestrial and freshwater ecosystems, we also reference marine systems when information on oceanic environments and taxa can provide insights for comparisons.