@article {bnh-4118, title = {Improving forest sampling strategies for assessment of fuel reduction burning}, journal = {Forest Ecology and Management}, volume = {392}, year = {2017}, month = {05/2017}, pages = {78-89}, chapter = {78}, abstract = {

Land managers\ typically make\ post hoc\ assessments of the effectiveness of fuel reduction burning (FRB), but often lack a rigorous sampling framework. A general, but untested, assumption is that variability in soil and fuel properties increases from small (\~{}1\ m) to large spatial scales (\~{}10{\textendash}100\ km). Based on a recently published field-based sampling scheme, we addressed the following questions: (i) How much variability is captured in measurements collected at different spatial scales? (ii) What is the optimal number of sampling plots required for statistically robust characterisation of burnt areas? (iii) How can land managers improve their assessment of the effectiveness of FRB? We found that measurement variability does not increase with scale for all fuel components. Results showed that\ coarse woody debris\ is as variable at the small scale (plot, m) as it is at the landscape scale (km). For certain fuel components, such as litter biomass (in unburnt areas),\ overstorey\ biomass and leaf area, and\ soil properties\ such as total carbon and total nitrogen, samples taken at the small (plot) scale were indicative of variation at the larger scale of an individual FRB and more broadly across the landscape.

We then tested the hypothesis that site stratification can reduce variability between sampling plots and as a consequence will reduce the required number of sampling plots. To test this hypothesis we used Landsat Normalized Difference Vegetation Index (NDVI) across areas treated with FRB and compared the number of sampling plots required to estimate mean fuel biomass with and without stratification. Stratification of burnt areas using remotely sensed vegetation indices reduced the number of sampling plots required. We provide a model of green biomass from Landsat NDVI and make recommendations on how sampling schemes can be improved for assessment of fuel reduction burning.

}, doi = {https://doi.org/10.1016/j.foreco.2017.03.001}, url = {http://www.sciencedirect.com/science/article/pii/S0378112716310751?via\%3Dihub}, author = {Gharun, Mana and Malcolm Possell and Jenkins, Meaghan E. and Lai Fan Poon and Bell, Tina and Adams, Mark A.} } @article {bnh-3416, title = {Production of pyrogenic carbon during planned fires in forests of East Gippsland, Victoria}, journal = {Forest Ecology and Management}, volume = {373}, year = {2016}, month = {08/2016}, pages = {9-16}, chapter = {9}, abstract = {

Management strategies such as planned burning for fuel reduction can help mitigate the effects of wildfires. The amount of biomass consumed is of interest to fire managers as reduction of fuel loads is imperative to reducing the risk and extent of a wildfire event. Biomass regeneration is also of importance for ecosystem recovery and resilience. Pyrogenic carbon (PyC), a product of combustion during both planned and unplanned fires, plays a key role in global carbon stores and balances. A three-year study of planned burning practices examined fires in Lowland temperate Eucalypt forest of south eastern Australia. We collected data on overstorey, understorey, coarse woody debris, fine litter, PyC and soil across nine sites to determine biomass consumption, PyC production and changes in ecosystem carbon during planned burning. Lowland forest showed significant recovery of combustible biomass (fine litter and understorey) one year after planned fire. Across our sites, PyC was produced at a rate of approximately 5\% of the biomass consumed. The PyC produced is destined to become part of soil and litter carbon and contributes to long-term carbon storage. Planned burning had a short-term (\<1\ year) impact on forest carbon balance, and on reduction risk of wildfire and associated losses of biomass carbon, but no long-term impact, through deposition of PyC and recovery of biomass.

}, doi = {10.1016/j.foreco.2016.04.028}, url = {http://www.sciencedirect.com/science/article/pii/S0378112716301979}, author = {Jenkins, Meaghan E. and Bell, Tina and Lai Fan Poon and Cristina Aponte and Adams, Mark A.} } @article {bnh-3431, title = {Emissions from prescribed fires in temperate forest in south-east Australia: implications for carbon accounting}, journal = {Biogeosciences}, volume = {12}, year = {2015}, month = {01/2015}, abstract = {

We estimated emissions of carbon, as equivalent CO2 (CO2e), from planned fires in four sites in a south-eastern Australian forest. Emission estimates were calculated using measurements of fuel load and carbon content of different fuel types, before and after burning, and determination of fuel-specific emission factors. Median estimates of emissions for the four sites ranged from 20 to 139 Mg CO2e ha-1. Variability in estimates was a consequence of different burning efficiencies of each fuel type from the four sites. Higher emissions resulted from more fine fuel (twigs, decomposing matter, near-surface live and leaf litter) or coarse woody debris (CWD; \> 25 mm diameter) being consumed. In order to assess the effect of declining information quantity and the inclusion of coarse woody debris when estimating emissions, Monte Carlo simulations were used to create seven scenarios where input parameters values were replaced by probability density functions. Calculation methods were (1) all measured data were constrained between measured maximum and minimum values for each variable; (2) as in (1) except the proportion of carbon within a fuel type was constrained between 0 and 1; (3) as in (2) but losses of mass caused by fire were replaced with burning efficiency factors constrained between 0 and 1; and (4) emissions were calculated using default values in the Australian National Greenhouse Accounts (NGA), National Inventory Report 2011, as appropriate for our sites. Effects of including CWD in calculations were assessed for calculation Method 1, 2 and 3 but not for Method 4 as the NGA does not consider this fuel type. Simulations demonstrate that the probability of estimating true median emissions declines strongly as the amount of information available declines. Including CWD in scenarios increased uncertainty in calculations because CWD is the most variable contributor to fuel load. Inclusion of CWD in scenarios generally increased the amount of carbon lost. We discuss implications of these simulations and how emissions from prescribed burns in temperate Australian forests could be improved.

}, doi = {10.5194/bg-12-257-2015}, url = {http://www.biogeosciences.net/12/257/2015/bg-12-257-2015-discussion.html}, author = {Malcolm Possell and Jenkins, Meaghan E. and Bell, Tina and Adams, Mark A.} } @article {BF-2587, title = {Respiratory quotients and Q10 of soil respiration in sub-alpine Australia reflect influences of vegetation types}, journal = {Soil Biology and Biochemistry}, year = {2011}, month = {3/2011}, abstract = {Identifying and quantifying attributes that help predict rates of heterotrophic soil respiration is a key issue. Similarly, assessing the temperature sensitivity (Q10) of soil C is critical to establishing if increases in Mean Annual Temperature will serve to further increase atmospheric CO2. Using organic soils from three sub-alpine communities that differ significantly in structure, species composition and productivity, we measured the respiratory quotient (RQ = rates of CO2 efflux/rates of O2 uptake) and temperature sensitivity of heterotrophic respiration during long-term (120 days) incubation. As a directly measurable parameter, RQ is free of empirical assumptions and provides an additional tool that can be used in conjunction with constants derived from fitted Arrhenius or exponential equations, to help understand shifts in microbial use of C substrates and how changes in vegetation might affect soil processes. Q10 did not change significantly over the course of a 120-day incubation for any of our studied soils. RQs varied with vegetation type and were consistently lower in grassland soils than woodland soils. RQs also varied during long-term incubations and declined consistently with time for grassland soils. RQs declined towards the end of the 120-day incubation for woodland soils. The generally low Ea for these soils from sub-alpine vegetation types in Australia, and the fairly rapid decline in RQ during incubation, suggest the likely greater temperature sensitivity of recalcitrant C relative to labile C could provide a strong positive feedback to increases in Mean Annual Temperature.}, doi = {10.1016/j.soilbio.2011.02.017}, author = {Jenkins, Meaghan E. and Adams, Mark A.} } @mastersthesis {BF-1173, title = {Carbon cycling in Sub-alpine Ecosystems.}, year = {2010}, school = {The University of New South Wales}, type = {Phd Thesis}, address = {Sydney}, author = {Jenkins, Meaghan E.} }