TESS seminars feature international, Australian, and local JCU researchers whose work falls within Tropical Environmental and Sustainability Sciences. Speakers are typically established or postdoctoral researchers.
- Where: Cairns Institute D3.054 in Cairns, video-linked to ATSIP 145-030 Townsville
- When: 4 - 5pm on the advertised date, followed by drinks and nibbles
- Who: All welcome!
If you are hosting a visitor or would like to give a seminar, please contact the seminar coordinator, Dr Yoko Ishida by email to firstname.lastname@example.org
TESS postgraduate students are encouraged to present at the annual TESS retreat.
Pyrogenic carbon abundance and isotope composition can be used to infer past change in tropical vegetation structure and function
Wednesday, 31st July 2019 | Presented by Prof Michael Bird|Australian Laureate Fellow, Distinguished Professor
Pyrogenic carbon (PyC; soot, char, black carbon) is produced by the incomplete combustion of organic matter accompanying biomass burning and fossil fuel consumption. It is pervasive in the environment, distributed throughout the atmosphere as well as soils, sediments and water in both the marine and terrestrial environment. As PyC is derived ultimately from plant material it retains information on the vegetation that was burnt, encoded in its stable carbon isotope composition. PyC preserves well in sedimentary archives because it is relatively resistant to degradation, and microcharcoal particle counting has long been used to generate proxy records of fire incidence in the past. In some circumstances, PyC is relatively easy to isolate but in many others, PyC is very small, ancient, and dispersed in a matrix (e.g. soil or sediment). Hydrogen pyrolysis (HyPy) is a technique that we have optimized for the quantification and isolation of PyC from a variety of matrices for determination of radiocarbon age and stable isotope composition.
Ecosystem d13C values vary widely across the tropics as a result of changes in the balance of vegetation using C4 versus C3 photosynthesis and information on changes in ecosystem C3:C4 balance can be obtained from the development of d13C time series from PyC in sedimentary archives. Stable isotope analysis of PyC in sedimentary archives by HyPy therefore offers the possibility of developing a more nuanced understanding of the interplay between fire regime and vegetation structure/function (and climate) in the tropics, in the past. This talk will provide an introduction to HyPy as an analytical tool and results from modern ground-truthing studies aimed at underpinning the interpretation of ancient PyC d13C time series. It will also present case studies where the technique has been used to develop proxy records of biomass burning and vegetation dynamics, where the results can be compared against particle counting approaches and palynological information
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