Prioritizing global tall forest toward the 30-by-30 goals

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The Global Deal for Nature sets an ambitious goal to protect 30% of Earth’s land and ocean by 2030. The 30×30 initiative is a way to allocate conservation resources and extend protection to conserve vulnerable and under protected ecosystems while reducing carbon emissions to combat climate change. However, most prioritization methods for identifying high-value conservation areas are based on thematic attributes and do not consider vertical habitat structure. Global tall forests represent a rare vertical habitat structure that harbors high species richness in various taxonomic groups and is associated with large amounts of aboveground biomass. Global tall forests should be prioritized when planning global protected areas toward reaching the 30×30 goals. We examined the spatial distribution of global tall forests based on the Global Canopy Height 2020 product. We defined global tall forests as areas with the average canopy height above 3 thresholds (20, 25, and30 m). We quantified the spatial distribution and protection level of global tall forests in high-protection zones, where the 30×30 goals are being met or are within reach, and low-protection zones, where there is a low chance of reaching 30×30 goals. We quantified the protection level by computing the percentage of global tall forest area protected based on the 2017 World Database on Protected Areas. We also determined the global extent and protection level of undisturbed, mature, tall forests based on the 2020 Global Intact Forest Landscapes mask. In most cases, the percentage of protection decreased as forest height reached the top strata. In the low-protection zones,<30% of forests were protected in almost all tall forest strata. In countries such as Brazil, tall forests had a higher per-centage of protection (consistently>30%) compared to forests of lower height, presenting a more effective conservation model than in countries such as the United States, where forest protection was almost uniformly<30% across height strata. Our results show an urgent need to target forest conservation in the greatest height strata, particularly in high-protection areas, where most global tall forests are found. Vegetation vertical structure can inform the decision-making process toward the 30×30 goals because it can be used to identify areas of high conservation value for biodiversity protection which also contribute to carbon sequestration.