State‐and‐transition simulation models: How can we use them to assess ecosystem condition and support nature markets

Abstract The world is experiencing a biodiversity crisis. Steep declines in habitat quality and ecosystem services have resulted in interest in markets to help fund ecological restoration. One way that ecological restoration is assessed is through indicators of ecosystem condition, namely, a measurement of how different a landscape is from its preindustrial or reference state. State‐and‐transition models (STMs) and their quantitative implementation, state‐and‐transition simulation models (STSMs), can be used to help assess ecosystem condition and to support nature markets. These models can simulate multi‐directional change in ecosystems across space and time and are useful tools for combining empirical data and expert knowledge. Here, we provide a brief review of STMs and how they relate to ecosystem condition. We then outline a protocol for building STMs and STSMs and using them to assess condition states at landscape scales. We argue that this is a powerful approach to incorporate many different types of information into an integrated, multi‐dimensional assessment of ecosystem condition. With this approach, STMs could support nature markets to drive widespread ecological restoration and reverse declines in biodiversity.