Trophic Cascade Disruption

Critically evaluate the consequences of anthropogenic disruption of trophic cascades in terrestrial ecosystems.

Throughout the biological history of the earth various mass extinction events have occurred (2) in which worldwide biodiversity greatly declined. Currently, we are in the process of the sixth mass extinction (3) which unlike those before it, is characterised be the loss of large bodied species and more specifically the loss of apex consumers (4.5). Furthermore; current extinctions are mainly as result of direct and indirect anthropogenic forces. And; like those before it this mass extinction event will induce evolutionary changes in the surviving species which in turn will cause variations in the structure and function of their
Specifically, it will review key ecological theory that forecasts trophic cascade disruption, consider difficulties in observing such affects and review the key empirical evidence for trophic cascade disruption. In doing so, this essay demonstrates the influence of predation and herbivory across global ecosystems and reveals extensive impacts of trophic disruption on the structure and dynamics of these systems. These findings suggest that trophic cascade disruptions act additively and synergistically with other anthropogenic mediated impacts on nature, such as climate and land use change, habitat loss, and
Discussed here are three key ideas that can help explain the processes involved in trophic disruption. Firstly; the idea of top down control that apex predators can exert on an ecosystem was popularised in the 1960s (9) this idea gave rise the concept of trophic cascades was which can be defined as the proliferation of impacts by consumers on their prey downward through food webs (11). Secondly the concept of alternative stable states arose from research into what influences ecosystem states. The complex dynamics of ecosystems result in distinctive basins of attraction, an alternative stable state can occur when a disturbance of sufficient magnitude push the ecosystem from on basin to another (12). The transition between states if often characterised around thresholds when once reached result in rapid changes in the ecosystem function and structure. This process can also exhibit hysteresis whereby the thresholds between states changes with the direction of change (13), meaning that reverting back to an original state is often more difficult. Lastly, the idea of connectivity proposes that ecosystems are made up of biological (predation, completion and mutualism) and physiochemical (limiting influences of water, temperature and nutrients) interactions where one species can potentially influence many other