Intra-annual isotope variations in tree rings reveal growth rhythms within the least rainy season of an ever-wet tropical forest

Jiménez, Jorge E.; Valle, Jorge I. del; González‐Caro, Sebastián; Sierra, Carlos A.

doi:10.1007/s00468-022-02271-7

Cited by 13 publications

(8 citation statements)

References 62 publications

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“…Stable oxygen isotope (δ 18 O) measurement of mammalian tissues provides additional palaeoecological information about feeding and drinking behaviours. In tropical ecosystems, δ 18 O of vegetation reflects either evaporative potential or the source-effect of rainfall (Buchmann et al, 1997;Buchmann and Ehleringer, 1998;Giraldo et al, 2022). The close association between plant δ 18 O and evaporative potential can, in turn, be used to infer forest canopy density.…”

Section: Stable Isotope Analysis and Human Palaeoecology In Eastern A...mentioning

confidence: 99%

Late Pleistocene to late Holocene palaeoecology and human foraging at Kuumbi Cave, Zanzibar Island

Iminjili

Stewart

Culley

et al. 2023

Front. Environ. Archaeol.

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BackgroundClimate change played a major role in shaping regional human-environment interactions in Africa during the late Pleistocene-Holocene, but this topic has not been exhaustively studied, particularly in eastern Africa. While there is growing evidence that the coastal and island settings in this region played a critical role in human evolution, combined archaeological and palaeoenvironmental studies have tended to focus on the arid interior and show the dominance of grasslands with patches of closed and open woodlands during the last 20,000 years.MethodsHere, we present stable carbon and oxygen isotope analyses of zooarchaeological remains (n = 229) recovered from Kuumbi Cave, Zanzibar Island, spanning the last glacial period and the Holocene (20,000 to 500 cal. BP).ResultsOur data demonstrate that the vicinity of Kuumbi Cave was consistently covered by mosaic habitats, dominated by forests and small patches of open woodland and grassland. The inhabitants of Kuumbi Cave exploited these diverse tropical habitats even after the regional arrival of agriculture.DiscussionWe suggest that the stable coastal forest mosaic habitats acted as a refugium for foragers during glacial periods and that the Iron Age inhabitants of Kuumbi Cave were not food producers migrating from the interior, but rather Indigenous foragers interacting with food production.

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Section: Stable Isotope Analysis and Human Palaeoecology In Eastern A...mentioning

confidence: 99%

Late Pleistocene to late Holocene palaeoecology and human foraging at Kuumbi Cave, Zanzibar Island

Iminjili

Stewart

Culley

et al. 2023

Front. Environ. Archaeol.

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“…Giraldo et al (2020) showed a high percentage of tree species with tree-ring structures (66 out of 81 tree species) from the Chocó region in northwestern South America, the rainiest region in the Americas with no evidence of seasonality in ecosystem productivity (Estupinan-Suarez et al, 2021). While it is not clear what factors control periodic growth rhythms in tropical trees under such conditions, slight variation in rainfall, soil moisture, solar irradiance, cloudiness and sunrise-sunset times are hypothesized as potential environmental drivers (Borchert & Rivera, 2001;Breitsprecher & Bethel, 1990;Clark & Clark, 1994;Giraldo et al, 2020Giraldo et al, , 2022. Light availability, namely photosynthetically active radiation (PAR), is a limiting factor in high cloud-cover regions such as ever-wet tropical forests (Restrepo-Coupe et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Scientific evidence of tropical annual tree rings mainly comes from tree species from both seasonally dry and seasonally flooded forests (Giraldo et al, 2020), demonstrating that both water deficit and excess determine seasonal growth patterns (Brienen et al, 2016; Rozendaal & Zuidema, 2011; Schöngart et al, 2017). However, the periodicity of tree‐ring formation in ever‐wet tropical forests and its potential drivers remain understudied (Giraldo et al, 2020, 2022).…”

Section: Introductionmentioning

confidence: 99%

Tree growth periodicity in the ever‐wet tropical forest of the Americas

et al. 2023

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The occurrence of annual growth rings in tropical trees—the result of the seasonal activity of vascular cambium—has been explained by seasonal water deficit or flooding periods. However, little is known about the drivers of annual tree‐ring formation under tropical hyper‐humid conditions without clear seasonal dry periods or flooding (ever‐wet conditions). Shelford's law states that the deficit or the excess of environmental resources limits plant growth. Accordingly, we hypothesize that excess soil moisture, a slight seasonal reduction of precipitation and a reduction in light availability determine rhythmic growth in ever‐wet tropical forests. We first assessed the occurrence of rhythmic growth in 14 tree species from the Biogeographic Chocó Region (annual rainfall 7200 mm) using three methods: Radiocarbon (14C) dating (all studied species), tree‐ring synchronization (4 species that have replicates) and automatic dendrometers (two species). Then, we assessed the effect of environmental drivers (rainfall, short‐wave radiation, temperature and soil moisture) on tree growth based on tree ring and dendrometer observations. We present evidence of annual tree‐ring formation in all 14 studied tree species. Depending on the tree species, we observed positive and negative correlations between growth, water availability and light availability. These relationships suggest that both excess or deficit of environmental resources may explain the seasonal pattern of tree growth. Although we cannot differentiate between excess soil water and low light availability by high cloudiness, we suggest that cloudiness frequency could affect tree growth in these forests. Synthesis. We reveal the annual formation of growth rings in the unexplored wetter‐end tropical forests, where seasonal growth depends on either high soil moisture and hypoxia or light limitations by cloudiness and photosynthesis constraints.

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“…δ 18 O TR values are an indicator of monsoonal precipitation on interannual to inter‐decadal times‐scales (Brienen et al., 2012; Granato‐Souza et al., 2019; Lopez et al., 2017; Rodriguez‐Caton et al., 2022), and they can also provide seasonal climatic information (Giraldo et al., 2022; Locosselli et al., 2020). Most previous tree‐ring oxygen isotope studies have been on an interannual scale and been focused on the west coast of South America, including the Amazon Basin and the Andes (Baker et al., 2015, 2016; Ballantyne et al., 2011; Brienen et al., 2012; Giraldo et al., 2022; Montecinos et al., 2000).…”

Section: Introductionmentioning

confidence: 99%

“…In the modern SASM region, δ 18 O TR is generally negatively correlated with precipitation, and it provides a record of local and regional precipitation variability (Baker et al, 2015(Baker et al, , 2016(Baker et al, , 2022Brienen et al, 2012;Locosselli et al, 2020). δ 18 O TR values are an indicator of monsoonal precipitation on interannual to inter-decadal times-scales (Brienen et al, 2012;Granato-Souza et al, 2019;Lopez et al, 2017;Rodriguez-Caton et al, 2022), and they can also provide seasonal climatic information (Giraldo et al, 2022;Locosselli et al, 2020). Most previous tree-ring oxygen isotope studies have been on an interannual scale and been focused on the west coast of South America, including the Amazon Basin and the Andes (Baker et al, 2015(Baker et al, , 2016Ballantyne et al, 2011;Brienen et al, 2012;Giraldo et al, 2022;Montecinos et al, 2000).…”

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confidence: 99%

Monthly Precipitation Reconstruction in Subtropical South America Using Seasonal Tree‐Ring Oxygen Isotopes

Liu,

Xu,

Fontana

et al. 2023

JGR Biogeosciences

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The South American Summer Monsoon (SASM) is one of the most important climate systems in the tropical and subtropical regions of South America, and transports Atlantic moisture to the South American continent. However, there are few high‐resolution tree ring based studies of the SASM due to the difficulty of crossdating and the lack of dependable moisture proxies based on tree‐ring width. In this study, we use intra‐annual tree‐ring oxygen isotope (δ18OTR) data (E.V.A 03w, E.V.Ar11e, E.V.Ar12e; the full name of sample code is Erval Velho ‐ Araucaria) for crossdating, and to extract climate signals and reconstruct monthly precipitation. Our data are from Araucaria angustifolia in southern Brazil, and each annual tree‐ring comprises four parts (parts 1, 2, 3, 4) during 1960–2016. The intra‐annual δ18OTR data show pronounced seasonal variations with a decreasing trend in the growing season. The intra‐annual δ18OTR data record variations in precipitation δ18O values, and the interannual δ18OTR data record a precipitation amount. The δ18OTR values of parts 1 and 2 of each ring show the strongest correlation with precipitation at the beginning of the SASM (i.e., December). δ18OTR values of Part 3 have the strongest correlation with precipitation during January–February, and those of Part 4 are strongly correlated with precipitation during February–June. The seasonal δ18OTR values can be used to reconstruct monthly precipitation in the growing season. Spatial correlations between monthly precipitation reconstruction and global sea surface temperatures reveal that EI Niño‐Southern Oscillation (ENSO) regulate seasonal precipitation and affect the δ18OTR values in southern Brazil.

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Intra-annual isotope variations in tree rings reveal growth rhythms within the least rainy season of an ever-wet tropical forest

Cited by 13 publications

References 62 publications

Late Pleistocene to late Holocene palaeoecology and human foraging at Kuumbi Cave, Zanzibar Island

Late Pleistocene to late Holocene palaeoecology and human foraging at Kuumbi Cave, Zanzibar Island

Tree growth periodicity in the ever‐wet tropical forest of the Americas

Monthly Precipitation Reconstruction in Subtropical South America Using Seasonal Tree‐Ring Oxygen Isotopes

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