NbS Triple Win Toolkit: Biodiversity Indicators in Context 29 Proposed Indicator The proposed indicator would report the size of the area over which funding supports ecological restoration where the end goal is close toa ‘natural’ state (note this does not exclude some levels of human use). Because the indicator aggregates information from projects involving different interventions and ecosystems, there is a need to establish consistency across projects as far as possible. As such, the indicatoris built around the definitions and approaches developed by the Society of Ecological Restoration (SER)32. SER define ecological restorationas a form of restoration that emphasises recovering a range of ecosystem attributes to a natural (or ‘reference’ state): “The process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed” with the aim to “assist recovery of native ecosystems and ecosystem integrity” Since the ultimate goal of ecological restoration is recovering ecosystem integrity relative to natural systems, it is distinct from apparently similar activities such as restoration designed primarilyto provide ecosystem services, or changes in management practices in production systems. Importantly, the SER view restoration as the activity undertaken, with the term ‘recovery’ being used to describe the outcome (i.e. the changes in ecosystem attributes that occur as a result of restoration). In this interpretation, ecological restoration is then: “any activity with the goal of achieving substantial ecosystem recovery relative to an appropriate reference model”. Describing an appropriate reference model is therefore central bothto individual projects and to ensuring comparability across projects.The SER define reference models as: “A model that indicates the expected condition that the restoration site would have been in had it not been degraded (with respect to flora, fauna and other biota, abiotic elements, functions, processes, and successional states). This condition is not the historic condition, but rather reflects background and predicted changes in environmental conditions” The reference model concept recognises that all ecosystems are the result of co-evolution between people, biodiversity, and environmental processes. In some cases, this means that the reference model can be one in which human use involves management that mirrors natural disturbance regimes (e.g. similarities in fire regimes between natural savannahs and those resulting from burning by indigenous people) or that is needed to support important native biodiversity32. The SER guidance also highlights the need to consider climate change when defining reference models, because the historical or current state of a native ecosystem may not be an appropriate (or even achievable) restoration target given future climate change impacts. Restoration could influence a large number of ecosystem attributes, which can be grouped into six broad categories: Absence of threats; Physical conditions; Species composition; Structural diversity; Ecosystem function; External exchanges (see methods guidance for detail of these categories). The status of these attributes can be assessed against the SER 5-star scale, which contains definitions for each broad category in a heavily impacted system (1 star) through to a natural or near-natural system (5 stars). The standardised scale facilitates fair comparison and aggregation across projects and ecosystems. Importantly, the definition of ecological restoration emphasises that the aspiration should be ‘substantial recovery’.This potentially allows for some level of human use, provided