ABSTRACT
Change in any environment is the norm. There is a degree of underlying stability in climatic, ecological and geomorphological conditions which is overlain by constant change and operating on different timescales. Cyclicity in environmental response to external change (especially climate and human activity) implies a degree of resilience within the system. This is manifest as resistance – a capacity to absorb change without altering structure (constancy) or an ability to return to a previous state (elasticity). However, most change is to some degree irreversible so cycles of change actually behave in a spiral manner with a longer-term trend of cumulative change. Spirals may be ‘downward’ (for example, deforestation leading to degradation) or ‘upward’ with terracing, which if maintained will increase the stability of the surface. The fundamental problem of studying environmental change lies in the difficulties involved in separating out the longer-term trends from the shorter-term impacts within this ‘spiralling’ structure. Consequently, depending upon the spatial and temporal scale of any set of observations, a particular ‘event’ may be interpreted as positive or negative and the process stable or unstable (Gigon 1983).
