TY - JOUR T1 - Baobabs at the edge: 90-year dynamics of climate variability, growth, resilience, and evolutionary legacy effects JF - Frontiers in Forests and Global Change Y1 - 2022 A1 - Mayne, Diana H. A1 - Karimi, Nisa A1 - Cruywagen, Elsie M. A1 - Cole, Patrick A1 - Goodall, Victoria AB - Climate variability and resilience remain gaps in tree research, challenged by the interacting factors in climate change, long-term resilience and the influence of evolutionary legacy effects. In a multidisciplinary approach using 90-year (1930–2020) climate-growth data, we investigated the dynamics of climate variability on growth and resilience of the tropical African baobab (Adansonia digitata) at the range edge in climate-variable, southeast Africa. The main driver of climate variability, ENSO (El Niño-Southern Oscillation), triggered 83% of droughts exacerbated by positive Indian Ocean Dipole (pIOD) events. Growth over 90 years was positively correlated with maximum temperature and increased after the 1976–1977 Global Warming Shift. The influence of warming was compromised by climate variability and extreme events. Although growth is a measure of adaptive capacity, accelerated growth over the past 20 years contrasted with dehydration, canopy dieback and a novel Didymella pathogen. Resilience was contingent on high genetic diversity (polyploidy and heterozygosity) and Neotropical legacy effects of stem water storage and longevity trade-offs of low growth, recruitment and reproduction. The evolution of resprouting in disturbed, fire-prone ecosystems and bark regeneration increased recovery from disturbance. As resource opportunists, baobabs adopted a fast-slow survival strategy. Rainfall and warming enhanced growth while low and variable rainfall favoured a conservative, low growth-higher survival strategy. Low rainfall, climate extremes and topography increased mortality risk. Mortality was higher at lower elevations on site and regionally. Low growth may conserve the baobab in climate warming but the southern hemisphere tropics is one of two identified global hotspots with amplified hot years. The heightened disturbance predicted from increased climate variability, hot droughts and landfalling tropical cyclones magnifies mortality risk for “Africa’s favourite tree.” VL - 5 UR - https://www.frontiersin.org/articles/10.3389/ffgc.2022.1036636 ER - TY - JOUR T1 - AMS radiocarbon investigation of the African baobab: Searching for the oldest tree JF - Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms Y1 - 2013 A1 - Patrut, Adrian A1 - von Reden, Karl F. A1 - Mayne, Diana H. A1 - Lowy, Daniel A. A1 - Patrut, Roxana T. AB - The Glencoe baobab, a very large specimen from South Africa, split twice in 2009. Several wood samples were collected from the eastern cavity, from the outer part of the main section and also from the largest broken segment which was connected to this section. These wood samples were processed and investigated by AMS radiocarbon dating. The radiocarbon date of the oldest sample was found to be 1838 +/- 21 BP, which corresponds to a calibrated age of 1835 +/- 40 years. Thus, the Glencoe baobab becomes the oldest dated baobab and also the oldest angiosperm tree with accurate dating results. The distribution of dating results revealed that the Glencoe baobab is a multi-generation tree, with several standing or collapsed and partially fused stems, showing different ages. (C) 2012 Elsevier B.V. All rights reserved. VL - 294 N1 - id: 2246; PT: J; CT: 12th International Conference on Accelerator Mass Spectrometry (AMS); CY: MAR 20-25, 2011; CL: Wellington, NEW ZEALAND; TC: 0; UT: WOS:000313234300120 JO - AMS radiocarbon investigation of the African baobab: Searching for the oldest tree ER - TY - JOUR T1 - Age determination of large live trees with inner cavities: radiocarbon dating of Platland tree, a giant African baobab JF - ANNALS OF FOREST SCIENCE Y1 - 2011 A1 - Patrut, Adrian A1 - von Reden, Karl F. A1 - Van Pelt, Robert A1 - Mayne, Diana H. A1 - Lowy, Daniel A. A1 - Margineanu, Dragos KW - Accelerator mass spectrometry KW - Adansonia digitata KW - Age determination KW - Growth rate KW - Radiocarbon dating AB - Introduction For large trees without a continuous sequence of growth rings in their trunk, such as the African baobab (Adansonia digitata L.), the only accurate method for age determination is radiocarbon dating. As of today, this method was limited to dating samples collected from the remains of dead specimens. Methods Our research extends significantly the dating of such trees to large live specimens with inner cavities. The new approach is based on collecting samples from the cavities and their subsequent radiocarbon dating. Results The giant two-stemmed Platland tree, also known as Sunland baobab, was investigated by using this new approach. AMS radiocarbon dates of the oldest sample segments originating from the two inner cavities indicate that the large stem I (364.5 m(3)) is 750 +/- 75 years old, while the much smaller stem II (136.7 m(3)) has 1,060 +/- 75 years. Results also show that stem I is still growing very fast, while the older stem II slowed down consistently its growth over the past 250 years. The complete mapping of Platland tree determined an overall wood volume of 501.2 m(3). Conclusions Dating results demonstrate that the size-age relation cannot be used for estimating accurately the age of African baobabs. VL - 68 ER - TY - JOUR T1 - Comparative AMS radiocarbon dating of pretreated versus non-pretreated tropical wood samples JF - Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms Y1 - 2010 A1 - Patrut, Adrian A1 - von Reden, Karl F. A1 - Lowy, Daniel A. A1 - Mayne, Diana H. A1 - Elder, Kathryn E. A1 - Roberts, Mark L. A1 - McNichol, Ann P. AB - Several wood samples collected from Dorslandboom, a large iconic African baobab (Adansonia digitata L.) from Namibia, were investigated by AMS radiocarbon dating subsequent to pretreatment and, alternatively, without pretreatment. The comparative statistical evaluation of results showed that there were no significant differences between fraction modern values and radiocarbon dates of the samples analyzed after pretreatment and without pretreatment, respectively. The radiocarbon date of the oldest sample was 993 +/- 20 BP. Dating results also revealed that Dorslandboom is a multi-generation tree, with several stems showing different ages. (C) 2009 Elsevier B.V. All rights reserved. VL - 268 IS - 7-8 N1 - id: 2083; PT: J; CT: 11th International Conference on Accelerator Mass Spectrometry; CY: SEP 14-19, 2008; CL: Rome, ITALY; SP: Univ Salento, CEDAD, Second Univ Naples, CIRCE, INNOVA, Ist Nazl Fis Nucl, LABEC, Abdus Salam Int Ctr Theoret Phys; UT: WOS:000277462300058 JO - Comparative AMS radiocarbon dating of pretreated versus non-pretreated tropical wood samples ER -