A proxy rainfall record for northeastern South Africa based on carbon isotope analysis of four baobab (Adansonia digitata L.) trees shows centennial and decadal scale variability over the last 1,000 years. The record is in good agreement with a 200-year tree ring record from Zimbabwe, and it indicates the existence of a rainfall dipole between the summer and winter rainfall areas of South Africa. The wettest period was c. AD 1075 in the Medieval Warm Period, and the driest periods were c. AD 1635, c. AD 1695 and c. AD1805 during the Little Ice Age. Decadal-scale variability suggests that the rainfall forcing mechanisms are a complex interaction between proximal and distal factors. Periods of higher rainfall are significantly associated with lower sea-surface temperatures in the Agulhas Current core region and a negative Dipole Moment Index in the Indian Ocean. The correlation between rainfall and the El Niño/Southern Oscillation Index is non-static. Wetter conditions are associated with predominantly El Niño conditions over most of the record, but since about AD 1970 this relationship inverted and wet conditions are currently associated with la Nina conditions. The effect of both proximal and distal oceanic influences are insufficient to explain the rainfall regime shift between the Medieval Warm Period and the Little Ice Age, and the evidence suggests that this was the result of a northward shift of the subtropical westerlies rather than a southward shift of the Intertropical Convergence Zone.
The article reports the radiocarbon investigation results of the Lebombo Eco Trail tree, a representative African baobab from Mozambique. Several wood samples collected from the large inner cavity and from the outer part of the tree were investigated by AMS radiocarbon dating. According to dating results, the age values of all samples increase from the sampling point with the distance into the wood. For samples collected from the cavity walls, the increase of age values with the distance into the wood (up to a point of maximum age) represents a major anomaly. The only realistic explanation for this anomaly is that such inner cavities are, in fact, natural empty spaces between several fused stems disposed in a ring-shaped structure. We named them false cavities. Several important differences between normal cavities and false cavities are presented. Eventually, we dated other African baobabs with false inner cavities. We found that this new architecture enables baobabs to reach large sizes and old ages. The radiocarbon date of the oldest sample was 1425 ± 24 BP, which corresponds to a calibrated age of 1355 ± 15 yr. The dating results also show that the Lebombo baobab consists of five fused stems, with ages between 900 and 1400 years; these five stems build the complete ring. The ring and the false cavity closed 800–900 years ago. The results also indicate that the stems stopped growing toward the false cavity over the past 500 years.
Assessing body mass in mammals is of importance as it influences virtually all aspects of mammal physiology, behavior and ecological parameters. However, the assessment of body mass of large mammals is potentially dangerous and logistically challenging. Photogrammetry (measurements through the use of photographs) is a well‐established science. In zoology it has been used with varying success to estimate the size and mass of some marine and terrestrial mammal species. However, photogrammetric body mass estimation of terrestrial mammals has received comparatively little attention. This is largely due to species' variable morphological attributes which complicates measurement especially if, for 3D orientation, photogrammetric models are dependent on identifiable features on the animals themselves. Ninety‐two individuals belonging to 16 terrestrial mammalian species were weighed and photographed for body mass estimation using a volumetric photogrammetry method, purposely applied with commercially available software. This method is not dependent on identifiable body features for 3D orientation. Measured body mass ranged from 25 kg to 4060 kg. Photogrammetric mass estimates versus physically weighed mass was plotted and the goodness of fit assessed for each species. Body size, shape and physiological attributes influence the accuracy of body mass estimation between species (although consistent within species), largely attributed to morphological features (e.g., hair length and posture). This photogrammetric method accurately estimated the body mass of several terrestrial mammal species. It represents innovative use of photographs to create calibrated three‐dimensional imagery for accurate quantification of mammalian metrics, specifically body volume and mass. Advances of a method that is not subject to species, sex or age is advantageous and suitable for wide application in our effort to model population demography.
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