Editing IPCC:AR6/WGII/Chapter-2 (section)

===== 2.4.4.3.2 Observed tree mortality in tropical ecosystems =====

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In the Brazilian Amazon, deforestation to clear agricultural land comprises the principal cause of tree mortality, reducing forest cover by an average of 13,900 km 2 yr -1 from 1988 to 2020 ( [[#Assis--2019|Assis et al., 2019]] ). In addition, in a set of 310 Amazon field plots, an annual average temperature increase of 1.2°C from 1950 to 2018 ( [[#Marengo--2018|Marengo et al., 2018]] ) contributed to tree mortality of ~40% from 1983 to 2011 ( [[#Brienen--2015|Brienen et al., 2015]] ). In another set of plots, mortality among newly recruited trees of mesic genera increased and drought-tolerant genera became more abundant from 1985 to 2015 ( [[#Esquivel-Muelbert--2019|Esquivel-Muelbert et al., 2019]] ). In other plots, tree mortality did not show a statistically significant change from 1965 to 2016, but rose abruptly in severe drought years, mainly during warm phases of the ENSO ( [[#Aleixo--2019|Aleixo et al., 2019]] ). Nearly half the area of the Amazon has experienced extremely dry conditions during ENSO warm phases; this can cause extensive wildfire ( [[#2.4.4.2.3|Section 2.4.4.2.3]] ). Wildfires can increase tree mortality rates by &gt;600% above rates in non-burned areas, with the higher mortality persisting for up to a decade after a fire ( [[#Silva--2018|Silva et al., 2018]] ; [[#Berenguer--2021|Berenguer et al., 2021]] ). Climate change has contributed to tree mortality in the Amazon rainforest ( ''medium evidence'' , ''medium agreement'' ).

In the African Sahel, field research has continued to detect tree mortality, ranging from 20 to 90% in the period 1965–2018 ( [[#Kusserow--2017|Kusserow, 2017]] ; [[#Trichon--2018|Trichon et al., 2018]] ; [[#Dendoncker--2020|Dendoncker et al., 2020]] ), and declines in tree biodiversity, with up to 80% local losses of tree species in the period 1970–2014 ( [[#Hanke--2016|Hanke et al., 2016]] ; [[#Kusserow--2017|Kusserow, 2017]] ; [[#Ibrahim--2018|Ibrahim et al., 2018]] ; [[#Dendoncker--2020|Dendoncker et al., 2020]] ), consistent with, but not formally attributed to, climate change. In Algeria, mortality of the Atlas cedar ( ''Cedrus atlantica'' ) increased from 1980 to 2006, coinciding with a ~1°C spring temperature increase, but non-climate factors were not examined ( [[#Navarro-Cerrillo--2019|Navarro-Cerrillo et al., 2019]] ). Across southern Africa, nine of the 13 oldest known (1100–2500 years old) baobab trees ( ''Adansonia digitata'' ) have died since 2005, although the causes are unknown ( [[#Patrut--2018|Patrut et al., 2018]] ). In South Africa, savanna trees experienced an order of magnitude increase in mortality, related, but not formally attributed to, decreased rainfall ( [[#Case--2019|Case et al., 2019]] ). In Tunisia, insect infestations related, but not formally attributed to, hotter temperatures led to mortality of cork oaks ( ''Quercus suber'' ) ( [[#Bellahirech--2019|Bellahirech et al., 2019]] ).

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