Editing IPCC:AR6/WGII/Chapter-9 (section)

==== 9.6.1.2 Vegetation Resilience ====

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African ecosystems have a long evolutionary association with fire, large mammal herbivory and drought ( [[#Maurin--2014|Maurin et al., 2014]] ; [[#Charles-Dominique--2016|Charles-Dominique et al., 2016]] ). The maintenance of biodiversity depends on natural disturbance regimes. Natural regrowth of savanna plant biomass in southern Africa compensated for biomass removal through human activities ( [[#McNicol--2018|McNicol et al., 2018]] ), and rapid recovery occurred after the 2014–2016 extreme drought ( [[#Abbas--2019|Abbas et al., 2019]] ). During the same drought event, browsing and mixed feeder herbivores were resilient, but grazers declined by approximately 60% and were highly dependent on drought refugia ( [[#Abraham--2019|Abraham et al., 2019]] ). African tropical forests remained a carbon sink through the record drought and temperature experienced in the 2015–2016 El Niño, indicating resilience in the face of extreme environmental conditions ( [[#Bennett--2021|Bennett et al., 2021]] ). This is likely due to the presence of drought-tolerant species and floristic and functional shifts in tree species assemblages ( [[#Fauset--2012|Fauset et al., 2012]] ; [[#Aguirre-Gutiérrez--2019|Aguirre-Gutiérrez et al., 2019]] ). This resilience indicates that there is the capacity to recover from disturbances and short-term change. However, resilience has limits and beyond certain points, change can lead to irreversible shifts to different states (Figure 9.18).

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'''Figure 9.18 |''' '''Increases in atmospheric CO''' '''2''' '''and changes in aridity are projected to shift the geographic distribution of major biomes across Africa (''' '''high confidence''' ''').''' Arrows in the diagram indicate possible pathways of biome change from current conditions resulting from changes in CO 2 and aridity. Changes need not be gradual or linear and may occur rapidly if tipping points are crossed. Currently, widespread greening observed in Africa has been at least partially attributed to increasing atmospheric CO 2 concentrations. Future projected increases in aridity are expected to cause desertification in many regions, but it is highly uncertain how this will interact with the greening effect of CO 2 . Inset maps show the projected geographical extent of changes in CO 2 concentrations and aridity. CO 2 is projected to increase globally under all future emission scenarios. Aridity index maps show projected change in aridity (calculated as annual precipitation/annual potential evapotranspiration) at around 4°C global warming relative to 1850–1900 (RCP8.5 in 2070–2099) from 34 CMIP5 models ( [[#Scheff--2017|Scheff et al., 2017]] ). Shaded areas indicate regions where &gt;75% of models agree on the direction of change.

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