Review on detection of critical transition in ecosystems

Abstract

Ecosystem with alternative stable states would respond abruptly to minor changes in the external conditions and switch into an alternative stable state with different ecosystem structures and functions when the system ap- proaches the transition threshold. This phenomenon is called critical transition. It is often the case that such transi- tion can result in marked changes in ecosystem services, which are much likely to impact the sustainable devel- opment of human being. It is difficult to predict the critical transitions in ecosystems, but the large amount of re- search in this field show that by monitoring some generic properties (i.e. early-warning signals) relating to eco- system status, we are able to discern if the system approaches the transition threshold; this can be used to predict the critical transitions in ecosystems. This paper summarizes the major findings and achievements in the field of detecting critical transitions in ecosystems. It first discusses the mechanism and consequence of critical transi- tions, and then introduces the basic theory behind the early-warning signals. We sum up the methods used to ex- tract early-warning signals both from temporal and spatial dimensions. Finally, challenges confronting the con- temporary research are summarized. In future, the application of early-warning signals should make full use of both temporal and spatial data and combine different indicators to improve our ability to forecast unfavorable en- vironmental events. Also, special attention needs to be paid to the relationship between critical transitions and