The research article titled “The positive impact of conservation action” published by Langhammer et al. (2024) in Science conducted a global meta-analysis of 186 studies that measured biodiversity over time and compared outcomes under conservation action with a suitable counterfactual of no action.
In a current biodiversity crisis of rapid and accelerating biodiversity losses, protecting species from extinction and ecosystems from degradation is very urgent. Some billions of dollars are already invested annually in conservation. To guide and amplify these efforts, an understanding of whether conservation initiatives actually result in positive outcomes for biodiversity is necessary.
Seven different types of conservation interventions were included in the analysis: (i) establishment and management of protected areas; (ii) other measures to reduce habitat loss and degradation such as policy and restoration; (iii) sustainable use of species; (iv) sustainable management of ecosystems; (v) control of pollution; (vi) eradication and control of invasive alien (and problematic native) species; and (vii) climate change adaptation.
The figure below depicts different possible impacts of conservation actions compared to a counterfactual. Four possible outcomes are outlined: - absolute positive impact: interventions generate gains in the state of biodiversity compared with a counterfactual in which biodiversity declines, stays the same, or improves to a lesser degree than the intervention (Fig. 1A) - relative positive impact: biodiversity declines but the intervention slows the decline compared with the counterfactual (Fig. 1B) - relative negative impact: biodiversity improves but the counterfactual reveals greater improvements than the intervention (Fig. 1C) - absolute negative impact: biodiversity declines following the intervention while it improves, stays the same, or declines to a lesser degree in the counterfactual (Fig. 1D)
Fig. 1. Schematic representation of different broad categories of conservation impact, with illustrative case studies drawn from the dataset used in Langhammer et al. (source: Langhammer et al. (2024), https://doi.org/10.1126/science.adj6598)
Langhammer et al. found that the majority of conservation actions did indeed have a net positive effect, with an overall positive and significant impact of conservation. In two thirds of cases, conservation either improved the state of biodiversity or at least slowed declines (45.4% absolute positive impact, 20.6% relative positive impact). Specifically, interventions targeted at species and ecosystems, such as invasive species control, habitat loss reduction and restoration, protected areas, and sustainable management, are highly effective (though there are variations depending on the specific context).
Building on this evidence that conservation actions are successful, the task is to scale them up. As J. W. Bull and J. E. Bicknell, second and third author of the study, put it in an article in The Conversation: “If conservation generally works but biodiversity is still declining, then simply put: we need to do more of it. Much more. While at the same time reducing the pressures we put on nature.”
Sources:
Penny F. Langhammer et al. (2024): The positive impact of conservation action. Science 384, 453-458 (2024). DOI:10.1126/science.adj6598, The positive impact of conservation action | Science