Using the conservation hierarchy entails a process of goal-setting, action planning, implementation of actions and monitoring progress.
The figure below, taken from Milner-Gulland et al. (2021), illustrates application of the MCH using a Plan-Do-Check-Act or Adaptive Management process. An overarching goal is set, with a timeline and a baseline. This is scaled down to specific targets for different sectors, locations and actors. The relevant implementers use the Four Steps approach to support planning of actions to implement targets, monitor outcomes, review and revise actions. Outcomes are integrated across scales, impact types and actors, and progress towards the goal is assessed.
Tracking progress towards biodiversity outcomes requires specification of metrics. Biodiversity metrics are the units in which the biodiversity of interest is measured, and in which losses, gains and net outcomes are expressed. The MCH is not prescriptive about which metrics to use, given that different metrics suit different applications and scales (Milner-Gulland et al. 2021). However, the Mitigation Hierarchy is designed to address specific sets of impacts with a requirement to demonstrate No Net Loss or Net Gain of biodiversity, so metrics for this component of the MCH are usually quantifiable.
Examples of biodiversity metric’s include the UK Government’s Biodiversity Metric 2.0; Rio Tinto’s Quality Hectares and Units of Global Distribution (see Temple et al. 2012); and Kering Group’s Biodiversity Impact Metric, which was developed by the University of Cambridge Institute for Sustainability Leadership. For more information on different metrics for different contexts, see our case studies. Conservation NGOs may also wish to adopt metrics to demonstrate positive conservation potential under the conservation hierarchy pathway, such as the Species Threat Abatement and Recovery (STAR) metric.
Metrics which allow consistent comparison of biodiversity gains and losses enable net outcomes to be calculated, although qualitative indicators can also be appropriate, for example when assessing people’s values for nature (Griffiths et al. 2018).