Genetic diversity must be explicitly recognized in ecological restoration

The Global Forest Watch estimated a net change of −101 Mha in tree cover between 2000 and 2020, and a net carbon sink of −5.59 GtCO₂e yr⁻¹ (ref. ²). Global degradation of seagrass could emit, on average, 1.15 GtCO₂ if no conservation measures are put in place³. Rising carbon emissions and associated climate change are happening alongside other types of anthropogenic disturbance, including land-use change, habitat loss and pollution, collectively disrupting biodiversity across diverse global ecosystems. Such magnitude of loss is linked to erosion of the genetic integrity in ecosystems: adaptive gene variants can be lost, gene flow networks altered⁴ and degraded sites are further prone to reduced effective population sizes due to increased genetic drift. Genetic diversity is crucial for disease resistance, fitness and the long-term survival of species, and is particularly important in the context of ongoing rapid multi-factor global change. For climate change in particular, as species’ habitats and ranges shrink in response, genetic homogenizations and loss of variation and adaptability potential have been observed⁵. Despite this, genetic diversity is often neglected in restoration planning and management, and seldom included in monitoring assessments of restoration outcomes.

The absence of clear language defining biodiversity in the UN and other restoration documents forces stakeholders to have to define it for themselves. Within a broader biodiversity context that includes species, functional and ecosystem diversity, genetic diversity may be less likely to be prioritized for a variety of reasons. In many regions and for most species (and populations), there remains a lack of an established baseline of genetic data, with costs and expertise required to obtain such baselines and conduct ongoing monitoring. Decisions on the sources of germplasm used in restoration typically prioritize short-term cost savings over long-term benefits⁶, despite the demonstrated potential for decreased long-term costs because there would be less need to replace planted trees in forest restoration⁶. In other contexts, for example community-led restoration projects, the concept of within-species (genetic) diversity may remain relatively obscure.