Skip to main content
2023 ESA Annual Meeting Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

Contributed Talk

Session: : Climate Change 4

COS 254-6 - Projected Drought Risk Among the World’s Tall and High Biomass Forests

Thursday, August 10, 2023
11:15 AM – 11:30 AM PDT
Location: B117
Abstract: Forests are of vast global importance. They are an integral part of the global carbon cycle and are a substantial carbon sink. In addition they are crucial to biodiversity and provide manifold ecosystem services. Forests containing the tallest trees are disproportionately important to these services. Droughts are increasingly becoming a threat to forests as they change in severity and frequency, specifically warmer, more intense droughts pose the most serious threat to forests. Additionally, large and old trees have been found to be more susceptible to drought induced mortality, thus the world's largest and oldest forests may be particularly vulnerable. By combining newly available data we can map projected departures from historical drought regimes among the world’s tallest forests as estimated through GEDI.



We used the gridded GEDI RH100 product to map the tallest forest pixels. We selected the tallest pixels as the >90th percentile within each forested WWF biome. We matched the height and biomass (GEDI L4B) data with their corresponding locations’ historic and projected future global SPEI from 9 global GCM models and calculated for both RCP 2.6 and RCP 8.5. All drought projections were carried out individually for each GCM and averaged. We found that by mid-century, mediterranean forests will be the most susceptible to increases in drought frequency (number of severe droughts (SPEI< -2) per decade), while mangroves and tropical forests will be the least. However, there is substantial geographic variation in biome-level projected drought susceptibility; the tallest tropical moist broadleaf forests within Neotropical and Palearctic regions, are projected to experience increases in severe drought frequency by 0.54-0.55 and 0.82-0.96 events per decade (RCP 2.6 and 8.5 respectively), yet only projected to increase by 0-0.25 and 0-0.40 events per decade elsewhere (Afrotriopical, Australasian, and Indomalaysian biogeographic realms). Tall forests overall are more susceptible to drought frequency increases in 20 out of 32 biome-by region groups in RCP 2.6 and 22 out of 32 in RCP 8.5. Nearly half (48.3%) of global forested biomass as estimated by GEDI is projected to experience at least an increase of 0.5 severe drought events per decade by mid-century in RCP 2.6. Understanding which regions of high biomass forests are at greatest risk of future droughts is key to conserving biomass and biodiversity.