Compensating for lost nature values through biodiversity offsetting – where is the evidence?

Abstract

Biodiversity offsetting is becoming a principal instrument for managing biodiversity and ecosystem services in society. Still, it is unclear whether biodiversity offsetting can fully mitigate losses to natural values. When reviewing published studies on offsetting, we found only 40 evaluations with primary outcome data on biodiversity or ecosystem services. Among these, we found no evidence that biodiversity gains from offsets actually compensate for development-associated losses, because losses were never estimated. The failure to quantify losses is troubling from a conservation perspective, as applying offsets that do not match up losses and gains will result in continued net loss of biodiversity. Instead, most studies (76%) included only reference habitats as comparator and evaluated singular taxa of biodiversity (66%), and rarely ecosystem services (ES). The overall meta-analysed effect size from reference habitat comparisons suggests that offsets perform poorly when contrasted to these habitats. There was a strong bias towards North American freshwater biomes, with only six published evaluations from terrestrial habitats. The bias and small number of studies precluded any detailed meta-analytical enquiries, such as identification of main drivers of outcomes. For biodiversity offsetting to be an important instrument for halting biodiversity losses, all actions must build on solid scientific evidence, and our review show that this evidence base is yet not in place. We conclude that there is a strong need for rigorous evaluation of offsetting projects, and to this end governments could request long-term monitoring programmes as an integral part of offsetting actions and make data openly available for assessment.

Keywords

biodiversity offsetting; no net loss; ecosystem services; habitat; species richness; ecological compensation; evaluation; meta-analysis

Published in

Biological Conservation
2021, volume: 257, article number: 109117

SLU Authors

• Josefsson, Jonas

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Ahlbäck Widenfalk, Lina

  • Department of Ecology, Swedish University of Agricultural Sciences
    
  • Greensway AB

• Hedblom, Marcus

  • Department of Ecology, Swedish University of Agricultural Sciences
    
  • Department of Urban and Rural Development, Swedish University of Agricultural Sciences
    

• Pärt, Tomas

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Ranius, Thomas

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Öckinger, Erik

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Ecology

Publication identifier

• DOI: https://doi.org/10.1016/j.biocon.2021.109117

Permanent link to this page (URI)

https://res.slu.se/id/publ/111788