point. Robert May used this stability analysis in the 1970s which uses the Jacobian matrix or community matrix to investigate the relation between the diversity and stability of an ecosystem. Types Although the characteristics of any ecological system are susceptible to changes, during a defined period of time, some remain constant, oscillate, reach a fixed point or present other type of behavior that can be described as stable. This multitude of trends can be labeled by different types of ecological stability. Dynamical stability Dynamical stability refers to stability across time. Stationary, stable, transient, and cyclic points A stable point is such that a small perturbation of the system will be diminished and the system will come back to the original point. On the other hand, if a small perturbation is magnified, the stationary point is considered unstable. Local and global stability In the sense of perturbation amplitude, local stability indicates that a system is stable over small short-lived disturbances, while global stability indicates a system highly resistant to change in species composition and/or food web dynamics. In the sense of spatial extension, local instability indicates stability in a limited region of the ecosystem, while global (or regional) stability involves the whole ecosystem (or a large part of it). Species and community stability Stability can be studied at the species or at the community level, with links between these levels. Constancy Observational studies of ecosystems use constancy to describe living systems that can remain unchanged. Resistance and inertia (persistence) Resistance and inertia deal with a system's inherent response to some perturbation. A perturbation is any externally imposed change in conditions, usually happening in a short time period. Resistance is a measure of how little the variable of interest changes in response to external pressures. Inertia (or persistence) implies that the living system is able to resist external fluctuations. In the context of changing ecosystems in post-glacial North America, E.C. Pielou remarked at the outset of her overview, "It obviously takes considerable time for mature vegetation to become established on newly exposed ice scoured rocks or glacial till...it also takes considerable time for whole ecosystems to change, with their numerous interdependent plant species, the habitats these create, and the animals that live in the habitats. Therefore, climatically caused fluctuations in ecological communities are a damped, smoothed-out version of the climatic fluctuations that cause them." Resilience, elasticity and amplitude Resilience is the tendency