doi:10.1111/nph.19598engBiancari, LucioAguiar, Martín R.Saiz, HugoGross, NicolasLe Bagousse-Pinguet, YoannEldridge, David J.Maestre, Fernando T.Upper boundary on tree cover at global drylandsART-2024-137644A comment on Holdo & Nippert (2023): ‘Linking resource- and disturbance-based models to explain tree–grass coexistence in savannas’ In their recent Tansley Review, Holdo & Nippert (2023) provide a comprehensive analysis of existing models that explain tree–grass coexistence along precipitation gradients in savannas. They highlight the diverse assumptions of the different models proposed in the literature and conclude that none can fully explain tree–grass coexistence along a rainfall gradient. Consequently, they propose essential elements that a synthetic model should incorporate to solve the ‘treeness conundrum’ (sensu House et al., 2003). Holdo & Nippert assert that tree dominance is mainly limited by ecohydrological mechanisms in dry savannas and by disturbances in wet savannas. These concepts and mechanisms are summarized in their fig. 1, where they modify the ‘Sankaran curve’ estimated for Africa (Sankaran et al., 2005) to account for the effect of soil texture along rainfall gradients (upper boundary on tree cover is achieved with lower precipitation in coarser than in fine soils).2024http://zaguan.unizar.es/record/13240210.1111/nph.19598http://zaguan.unizar.es/record/132402oai:zaguan.unizar.es:132402info:eu-repo/grantAgreement/EC/H2020/647038/EU/Biological feedbacks and ecosystem resilience under global change: a new perspective on dryland desertification/BIODESERTThis project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 647038-BIODESERTinfo:eu-repo/grantAgreement/ES/MICINN-AEI-FEDER/PID2020-116578RB-I00New Phytologist 242, 3 (2024), 836-840All rights reservedhttp://www.europeana.eu/rights/rr-f/info:eu-repo/semantics/openAccess