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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 (∼10–100 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 E a 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. [Copyright &y& Elsevier]

• It is often assumed that most biomass is consumed in fire. • However, often only "fine" biomass (<6 mm diameter) is consumed. • We present allometric equations to quantify the mass of fine fuel in shrubs. • Planned burns reduced fine fuel loads, but above-ground biomass losses were small. Accurate quantification of fine fuel loads (e.g. foliage and twigs) in forests is required for many fire behaviour models, and for assessing post-fire changes in carbon stocks and modelling smoke emissions. Fine fuels burn readily and are thus often targeted for fuel load assessments. Estimates of fine live fuel loads often rely on visual assessments or utilise allometric equations that relate stem diameter of plants to total above-ground biomass. Here, we develop allometric equations for shrubs that relate stem diameter to the portion of above-ground biomass comprised of fine fuel. Our study area is within the temperate eucalypt forests of south-eastern Australia. We present equations for (i) foliage; (ii) all biomass < 3 mm diameter; (iii) all biomass < 6 mm diameter; and (iv) all above-ground biomass. Simple power-law models were developed for five shrub species and saplings of two tree species. Models combining all species (RMSE = 0.03–0.0.06) worked similarly well to species-specific models (RMSE = 0.01–0.08). We then applied these all-species combined models to field observations of shrub stem diameters, measured before and after planned burns. In unburnt forest, the proportion of shrub biomass comprised of fine fuel varied considerably (from 6 to 58%). Fine fuel loads were positively related to total above-ground biomass (R 2 = 0.75) and basal area of shrubs (R 2 = 0.79). There was considerable variation in consumption of fine fuel. The median reduction in fine fuel load was 22.4%, whereas the median reduction in total above-ground biomass was only 2.3%. Our models of shrub fine fuels can be readily applied to field-based assessments or combined with existing models or remotely sensed estimates of above-ground biomass to model fine fuel loads over large heterogeneous study areas. [ABSTRACT FROM AUTHOR]

• We test inter-fire interval impacts on fauna and their habitat 15-years post-fire. • Most fauna and habitat variables were unaffected by inter-fire interval. • However, brush-tailed possums were more common at longer than shorter intervals. • Forests were dominated by large, tall trees in these areas. • Inter-fire interval can propagate indirect effects pathways long after wildfire. Attributes of the historical fire regime can influence fauna dynamics by moderating vegetation composition and the availability of appropriate habitat. Despite this, the indirect impacts of specific aspects of the long-term fire regime are often overlooked. Here we conduct a field survey at 27 sites in sub-alpine forests of Namadgi National Park (Australia) to determine if one aspect of the historical fire regime, inter-fire interval, influences vertebrate fauna and fauna habitat. Sites were stratified between three inter-fire interval categories (20, 65–70 and 83 years between the previous two fires) in areas last burned 15-years prior to the field survey. All other environmental attributes thought to impact vegetation dynamics were controlled for in the study design. Fauna activity was monitored for four weeks using trail cameras and 15 habitat attributes were assessed using field and remote-sensing survey techniques. Most fauna and habitat variables did not differ among the inter-fire interval categories. However, mountain brush-tail possum detections increased with inter-fire interval length, with 260% more observations within the older treatment when compared with the younger treatment. Large tree density, maximum tree height, and tree canopy cover were 40%, 38% and 12% higher within the older than younger treatment, respectively. Conversely, small tree density was 78% lower within the older treatment. Our results show a limited response of fauna to historical fire-return intervals of >20 years within a fire-prone forest, however also highlight that species-/habitat-specific responses do manifest via indirect effects pathways at longer fire return intervals. [ABSTRACT FROM AUTHOR]