@article {bnh-6978, title = {Quantifying the conversion of vegetation to ash for soil carbon fingerprinting}, number = {572}, year = {2020}, month = {06/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Samples of leaves, twigs and bark representing typical surface fuels from forests and woodlands were systematically heated and combusted under controlled conditions. Very little biomass, carbon (C) and nitrogen (N) was lost when heated at low temperatures to 200 {\textdegree} and greatest losses occurred between 400 and 600

{\textdegree}C, regardless of the type of fuel burnt. Losses of C and N varied considerably with temperature. Carbon was lost when fuels were heated at temperatures of 300 {\textdegree}C or more. Nitrogen was relatively more abundant when heated at 400 {\textdegree}C, albeit at very low levels (less than 5\%). When heating time was varied there were noticeable differences in patterns of weight loss and changes in proportions of C and N. This indicates that both fire intensity and residence time is likely to be important in understanding losses of C and nutrients during fire, particularly during low intensity prescribed burning.

The use of colour of residues after heating surface fuel has the potential to determine fire severity. Existing technology such as near infra-red scanners can measure ash colour, not only indicating fire severity but also, by association, C and N losses from fire. Combustion studies done in a well-controlled laboratory environment could be used to interpret fireground conditions in relation to fire intensity and residence time, according to the nature and amount of charred material, charcoal and ash that remains after fire.

}, keywords = {Ash, milestone, soil carbon fingerprinting, vegetation}, issn = {572}, author = {Danica Parnell and Bell, Tina and Malcolm Possell} } @article {bnh-5401, title = {Influence of controlled burning on the mobility and temporal variations of potentially toxic metals (PTMs) in the soils of a legacy gold mine site in Central Victoria, Australia}, journal = {Geoderma}, volume = {331}, year = {2018}, chapter = {1}, abstract = {

Controlled burns also known as managed burns or prescribed fires conducted in fire-prone areas are an efficient and economic option to reduce the frequency and intensity of\ wildfires. The objective of this study is to investigate the\ remobilizationof potentially\ toxic metals\ (PTMs) in the soils of a legacy\ gold mine\ site in Central Victoria, Australia after a controlled burn and to describe their\ temporal variationsin concentrations. Soil samples were collected two days before, two days after and five times later (3, 6, 9, 12 months and after major rainfall) in the post-burn environment after a controlled burn, from the Maldon legacy mine site and analysed for PTM concentrations. The results revealed PTM mobilization after the burn and most of the PTMs (As, Cd, Cu, Mn, Ni, and Zn) evidenced an increase immediately after the burn but a reduction in the subsequent post-burn environment. The increase is postulated to be associated with addition of PTM enriched ash to the soil, while the decrease is due to the removal of ash and surface soil by wind activity as well as rainfall\ runoff\ and\ leaching. The PTM mobility is of specific concern due to the negative impacts on human and\ ecosystems health.\ Climate change\ and the resulting projection of increased\ forest fire\ frequency highlight the environmental significance, given the expected concomitant increase in PTM mobilization through wildfires and controlled burns. Hence, the practice of controlled burning should be carefully considered as a\ forest management\ option in any legacy mining areas and indeed in other areas where PTM\ contamination\ is reported.

}, keywords = {Ash, forest fire, Forest management, Metal mobility, prescribed fire, Soil and water contamination}, doi = {https://doi.org/10.1016/j.geoderma.2018.06.010}, url = {https://www.sciencedirect.com/science/article/pii/S0016706117320001}, author = {Joji Abraham and Kim Dowling and Singarayer Florentine} }