Before revision:  This paper explores the destabilising feedback loops in predator-prey, mutualistic and competitive systems and shows how matrix structure plays a significant role in their stability. A method is then described in which a variable acting on the self-regulating terms of the community matrix enables one to determine the size of the key feedback that leads to a system's tipping point  .
After revision:  This paper explores the destabilising feedback loops in predator-prey, mutualistic and competitive systems in terms of sets of the matrix elements to explore how sign structure affects how the elements contribute to instability. An analytic method is then described in which a variable acting on the self-regulating terms of the community matrix enables one to determine the size of the key feedback that leads to a system's tipping point .