Bioavailability of Macro and Micronutrients Across Global Topsoils: Main Drivers and Global Change Impacts

Understanding the chemical composition of our planet\u27s crust was one of the biggest questions of the 20th century. More than 100 years later, we are still far from understanding the global patterns in the bioavailability and spatial coupling of elements in topsoils worldwide, despite their importance for the productivity and functioning of terrestrial ecosystems. Here, we measured the bioavailability and coupling of thirteen macro- and micronutrients and phytotoxic elements in topsoils (3–8 cm) from a range of terrestrial ecosystems across all continents (∼10,000 observations) and in response to global change manipulations (∼5,000 observations). For this, we incubated between 1 and 4 pairs of anionic and cationic exchange membranes per site for a mean period of 53 days. The most bioavailable elements (Ca, Mg, and K) were also amongst the most abundant in the crust. Patterns of bioavailability were biome-dependent and controlled by soil properties such as pH, organic matter content and texture, plant cover, and climate. However, global change simulations resulted in important alterations in the bioavailability of elements. Elements were highly coupled, and coupling was predictable by the atomic properties of elements, particularly mass, mass to charge ratio, and second ionization energy. Deviations from the predictable coupling-atomic mass relationship were attributed to global change and agriculture. Our work illustrates the tight links between the bioavailability and coupling of topsoil elements and environmental context, human activities, and atomic properties of elements, thus deeply enhancing our integrated understanding of the biogeochemical connections that underlie the productivity and functioning of terrestrial ecosystems in a changing world

Dating the Dreaming: extinct fauna in the petroglyphs of the Pilbara region, Western Australia

Examples of striped marsupial depictions have been reported from both the coastal and inland Pilbara. Many are regarded as images of the thylacine, an animal that disappeared from mainland Australia some 3000–4000 years ago. Also observable in the rock art is the 'fat-tailed macropod', a distinctive rendition of a marsupial with an extremely thick tail. Recent investigations in the Tom Price area and on the Burrup Peninsula confirm that both motifs pertain to the more ancient rock art corpus. Restricted artistic variation within the depiction of these two species confirms the trend to naturalistic style within animal subjects and suggests a extensive, culturally cohesive, artistic tradition across the Pilbara during the Pleistocene and early Holocene. At two specific locations, aspects of the rock art may be explained in terms of contemporary oral traditions and cultural practices, affording one way of placing temporal parameters on these early graphic traditions. I argue that the rock art is not just representational; that it communicates mythological narratives and behavioural traits, which have a deep antiquity to the Dreaming of more than just a few thousand years

Of Turtles in Particular: a Distributional Study of an Archaeological Landscape in Southern Burrup

An audit of rock art and other archaeological sites was undertaken of a limited area of the Pilbara Iron lease, on the Burrup Peninsula, Western Australia. An analysis of the finds found that occupation was focused on two rich resource areas, foreshore and inland waterholes. Rock art, however, was found throughout the area but was more concentrated around the inland waterholes, with secondary concentrations on the foreshore but not in association with the coastal midden. Examination of the variation of one particular motif, turtles, showed that while reflecting the pattern of overall motif concentrations, particular patterned forms did not occur over the whole area. One interpretation of the distribution could be that individual patterns were produced (or owned) by particular groups or persons. It is also possible that the stylistic forms reflect chronological phases in the production of rock art

Changing ecological concerns in rock-art subject matter of north Australia\u27s Keep River region

The Keep River region has a complex body of engraved and painted rock-art, distinct from but with links to regions to the east, west and south. At least four major periods of figurative rock-art have been identified with differing subject matters and ages. Significant changes in depictions of human figures and animals are evident, reflecting shifts in emphasis associated with ecological concerns and environmental change. We flesh out the relative rock-art chronology by highlighting these changes, from worlds dominated by humans to those dominated by mammals and birds, and finally to a recent world of reptiles and humans. Symbolic aspects of the imagery are also considered within a larger ecological approach

Food or fibercraft? Grinding stones and Aboriginal use of Triodia grass (spinifex)

Plant tissue and wooden objects are rare in the Australian archaeological record but distinctive stone tools such as grinding stones and ground-edge hatchets are relatively common, and they provide strong indirect evidence for plant food processing and woodworking, respectively. Ethnohistorical references to the Aboriginal use of stone tools for technologies related to fibercraft, basketry, hafting adhesives and fixative sealants (with gum, wax and resin) are also rare but all these tasks were probably more common than records indicate. Here we consider ethnohistorical evidence for stones in fibercraft and the processing of Triodia grass (spinifex) as a case study. We compare functional traces on experimental stones with traces on a museum specimen (CMAA 1926.591), which was collected ethnohistorically and reportedly used for \u27grinding spinifex leaves\u27. Residues and other traces on the museum specimen are consistent with both fiber-processing and seed grinding. We suggest that it may be difficult for usewear and residue analysis to determine if grinding stones were used to target Triodia spinifex for fiber, food or another particular plant product. Further experimental research is needed to refine criteria for identifying archaeological fiber-processing tools. However, we propose that the combination of traces previously interpreted as seed processing on bedrock grinding patches and portable grinding stones may also indicate the processing of Triodia spinifex for fiber

Comparison of sedimentation and occupation histories inside and outside rock shelters, Keep-River Region, Northwestern Australia

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Changing ecological concerns in rock-art subject matter of north Australia’s Keep River region

The Keep River region has a complex body of engraved and painted rock-art, distinct from but with links to regions to the east, west and south. At least four major periods of figurative rock-art have been identified with differing subject matters and ages. Significant changes in depictions of human figures and animals are evident, reflecting shifts in emphasis associated with ecological concerns and environmental change. We flesh out the relative rock-art chronology by highlighting these changes, from worlds dominated by humans to those dominated by mammals and birds, and finally to a recent world of reptiles and humans. Symbolic aspects of the imagery are also considered within a larger ecological approach

A new bipolar ice core record of volcanism from WAIS Divide and NEEM and implications for climate forcing of the last 2000 years

Volcanism is a natural climate forcing causing short-term variations in temperatures. Histories of volcanic eruptions are needed to quantify their role in climate variability and assess human impacts. We present two new seasonally resolved, annually dated non-sea-salt sulfur records from polar ice cores - WAIS Divide (WDC06A) from West Antarctica spanning 408 B.C.E. to 2003 C.E. and NEEM (NEEM-2011-S1) from Greenland spanning 78 to 1997 C.E. - both analyzed using high-resolution continuous flow analysis coupled to two mass spectrometers. The high dating accuracy allowed placing the large bi-hemispheric deposition event ascribed to the eruption of Kuwae in Vanuatu (previously thought to be 1452/1453 C.E. and used as a tie-point in ice core dating) into the year 1458/1459 C.E. This new age is consistent with an independent ice core timescale from Law Dome and explains an apparent delayed response in tree rings to this volcanic event. A second volcanic event is detected in 1453 C.E. in both ice cores. We show for the first time ice core signals in Greenland and Antarctica from the strong eruption of Taupo in New Zealand in 232 C.E. In total, 133 volcanic events were extracted from WDC06A and 138 from NEEM-2011-S1, with 50 ice core signals - predominantly from tropical source volcanoes - identified simultaneously in both records. We assess the effect of large bipolar events on temperature-sensitive tree ring proxies. These two new volcanic records, synchronized with available ice core records to account for spatial variability in sulfate deposition, provide a basis for improving existing time series of volcanic forcing