@article {2509,
	title = {Quantifying bamboo coral growth rate nonlinearity with the radiocarbon bomb spike: A new model for paleoceanographic chronology development},
	journal = {Deep Sea Research Part I: Oceanographic Research Papers},
	year = {2017},
	month = {Jan-04-2017},
	abstract = {Bamboo corals, long-lived cold water gorgonin octocorals, offer unique paleoceanographic archives of the intermediate ocean. These Isididae corals are characterized by alternating gorgonin nodes and high Mg-calcite internodes, which synchronously extend radially. Bamboo coral calcite internodes have been utilized to obtain geochemical proxy data, however, growth rate uncertainty has made it difficult to construct precise chronologies for these corals. Previous studies have relied upon a single tie point from records of the anthropogenic Δ14C bomb spike preserved in the gorgonin nodes of live-collected corals to calculate a mean radial extension rate for the outer ~50 years of skeletal growth. Bamboo coral chronologies are typically constructed by applying this mean extension rate to the entire coral record, assuming constant radial extension with coral age. In this study, we aim to test this underlying assumption by analyzing the organic nodes of six California margin bamboo corals at high enough resolution (<0.5 mm) to identify the Δ14C bomb spike, including two tie points at 1957 and 1970, plus the coral collection date (2007.5) for four samples. Radial extension rates between tie points ranged from 10 to 204 {\textmu}m/year, with a decrease in growth rate evident between the 1957{\textendash}1970 and 1970{\textendash}2007.5 periods for all four corals. A negative correlation between growth rate and coral radius (r =-0.7; p=0.04) was determined for multiple bamboo coral taxa and individuals from the California margin, demonstrating a decline in radial extension rate with specimen age and size. To provide a mechanistic basis for these observations, a simple mathematical model was developed based on the assumption of a constant increase in circular cross sectional area with time to quantify this decline in radial extension rate with coral size between chronological tie points. Applying the area-based model to our Δ14C bomb spike time series from individual corals improves chronology accuracy for all live-collected corals with complete Δ14C bomb spikes. Hence, this study provides paleoceanographers utilizing bamboo corals with a method for reducing age model uncertainty within the anthropogenic bomb spike era (~1957-present). Chronological uncertainty is larger for the earliest portion of coral growth, particularly for skeleton precipitated prior to bomb spike tie points, meaning age estimations for samples living before 1957 remain uncertain. Combining this technique with additional chronological markers could improve age models for an entire bamboo coral. Finally, the relative consistency in growth rate in similarly-aged corals of the same depth and location supports the hypothesis that skeletal growth may be limited by local environmental conditions.},
	keywords = {14C nuclear bomb spike, Bamboo coral, Chronologies, Gorgonin, Growth rate, paleoceanography, radiocarbon},
	issn = {09670637},
	doi = {10.1016/j.dsr.2017.04.006},
	url = {https://doi.org/10.1016/j.dsr.2017.04.006},
	author = {Frenkel, M.M. and LaVigne, M. and Miller, H.R. and Hill, T.M. and McNichol, A. and Gaylord, M. Lardie}
}
@article { ISI:000294494900012,
	title = {Age determination of large live trees with inner cavities: radiocarbon dating of Platland tree, a giant African baobab},
	journal = {ANNALS OF FOREST SCIENCE},
	volume = {68},
	number = {{5, SI}},
	year = {2011},
	month = {AUG},
	pages = {993-1003},
	type = {Article},
	abstract = {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.},
	keywords = {Accelerator mass spectrometry, Adansonia digitata, Age determination, Growth rate, Radiocarbon dating},
	issn = {1286-4560},
	doi = {10.1007/s13595-011-0107-x},
	author = {Patrut, Adrian and von Reden, Karl F. and Van Pelt, Robert and Mayne, Diana H. and Lowy, Daniel A. and Margineanu, Dragos}
}
