A state-and-transition model framework to take stock of natural capital on farms

Context

Natural capital accounting is an emerging approach to help address the challenge of preventing further biodiversity loss while sustainably providing resources for a growing human population. It requires an effective and robust framework for quantifying natural capital on farms. State and transition models (STMs) have been used extensively to describe the range of observable condition states for an ecosystem and the processes that maintain states or drive shifts between them. Current STM frameworks have limited capacity for use in modified landscapes and therefore are currently unsuitable for many applications of natural capital accounting.

Objective

We aimed to develop an extended STM framework, using ‘Eucalyptus woodlands of south-eastern Australia’ as an example, to categorise ecological condition states unambiguously in high-resolution across whole farms.

Methods

We used synthesised current literature, consulted experts, and conducted field visits to develop and refine the STM.

Results and conclusions

We developed an STM that defines 35 condition states observable on farms in south-eastern Australia, ranging from ‘reference’ condition woodlands that have experienced minimal disturbance to highly modified derived grasslands and crops. The STM framework can be used to assign an ecological condition state to all areas on a farm.

Significance

The STM described here marks a significant advancement in farmland ecology and natural resource management. Using this tool and adapting the states and thresholds to fit other vegetation types, all ecosystems on a farm can be categorized based on ecological condition, which can then be mapped across whole farms. Ecosystem state mapping can be used to guide restoration actions, management trade-offs and track changes in ecological condition over time. These maps can be used to quantify natural capital on farms to form the basis of natural capital accounts and infer ecosystem service provision. This framework will facilitate biodiversity credential certification and help enable farmers to access price premiums and restricted markets, and ultimately, will enhance biodiversity conservation in farmlands while also enabling appropriate decisions regarding continuing agronomic use.