Alternative stable states in ecology

Abstract

The idea that alternative stable states may exist in communities has been a recurring theme in ecology since the late 1960s, and is now experiencing a resurgence of interest. Since the first papers on the subject appeared, two perspectives have developed to describe how communities shift from one stable state to another. One assumes a constant environment with shifts in variables such as population density, and the other anticipates changes to underlying parameters or environmental “drivers”. We review the theory behind alternative stable states and examine to what extent these perspectives are the same, and in what ways they differ. We discuss the concepts of resilience and hysteresis, and the role of stochasticity within the two formulations. In spite of differences in the two perspectives, the same type of experimental evidence is required to demonstrate the existence of alternative stable states.

Management of a shallow temperate estuary to control eutrophication: The effect of hydrodynamics on the system’s nutrient loading

“…7. A) Comparison of the mean concentration of chlorophyll a (mg m ÿ3 , mean GSE) and the mean biomass of green macroalgae (mg AFDW m ÿ2 , mean GSE) before the management (1993e1997) and after (1999e2003); B) Comparison of the mean biomass of Zostera noltii at the long monitoring field station A (mg AFDW m ÿ2 ) before the management (1993e1997) and after (1999e2003); C) Hypothetical pattern of change in the relative contribution of these three major groups of producers in shallow temperate estuaries with shorter water residence time, redrawn after Valiela et al (1997). abrupt and the ecosystem response to perturbation is highly non-linear and complex (Scheffer et al, 2001;Beisner et al, 2003;Marques et al, 2003;Zhang et al, 2003;Cardoso et al, 2004). The non-linearity arises from the strong interactions between the benthos and the pelagic compartments and from competition between primary producers for light and nutrients (Scheffer et al, 2001;Zhang et al, 2003;Webster and Harris, 2004).…”

“…nutrient loads reduction) is very different from the trajectory as the driving variable intensifies (e.g. rising nutrient loads), the system shows pronounced hysteresis (Scheffer et al, 2001;Beisner et al, 2003;Webster and Harris, 2004). Eutrophication may push the system into an alternate stable state by positive feedback processes from which recovery is very difficult to achieve (Scheffer et al, 2001).…”

Inferring species interaction networks from species abundance data: A comparative evaluation of various statistical and machine learning methods

“…Tampering with the population of one species can cause surprising and dramatic changes in the populations of others (Cohen et al, 1994;Henneman and Memmott, 2001). Altering pressures to which ecosystems are exposed can drive them to alternative states (Beisner et al, 2003) or catastrophic failure (Sinclair and Byrom, 2006). Understanding and predicting how ecosystems will respond to change requires untangling the 2 tangled bank and is of enormous importance during a period of rapid global change.…”

Caught between two Allee effects: Trade-off between reproduction and predation risk

“…Alternatively, our model describes a pest species that needs to be controlled or eradicated. To quantify the extinction risk and eradication potential we use population resilience, defined as the maximum disturbance the population in a stable state may sustain to avoid extinction (Beisner et al, 2003), and relative population resilience, by which we mean a relative change in the resilience of the population after a predator removal/addition. When measuring relative resilience, we also distinguish prey with flexible and inflexible reproductive behaviour.…”