Fire impacts soil hydrology and biogeochemistry at both near (hours to days) and long (decades to centuries) time scales. Burns, especially in soils with high organic carbon stocks like peatlands, induce a loss of absolute soil carbon stock. Additionally, fire can alter the chemical makeup of the organic matter, potentially making it more resistant to decomposition. On the shorter timescales, fire can also change the water repellent properties or hydrophobicity of the soil, leading to an increased risk of debris flows and floods.
In this session, we will focus on the varying data needs for assessing the effects of burns across time scales, from informing emergency response managers in the immediate post-burn days, to monitoring post-burn recovery, to managing carbon in a landscape decades out.
Speaker abstracts (in order of presentation):
James MacKinnon (NASA GSFC)
Machine learning methods for detecting wildfires This talk shows the innovative use of deep neural networks, a type of machine learning, to detect wildfires in MODIS multispectral data. This effort attained a very high classification accuracy showing that neural networks could be useful in a scientific context, especially when dealing with sparse events such as fire anomalies. Furthermore, we laid the groundwork to continue beyond binary fire classification towards being able to detect the "state," or intensity of the fire, eventually allowing for more accurate fire modeling. With this knowledge, we developed software to enable neural networks to run on even the typically compute-limited spaceflight-rated computers, and tested it by building a drone payload equipped with a flight computer analog and flew it over controlled burns to prove its efficacy.
Kathe Todd-Brown (U. FL Gainesville)
An overview of effects of fire on ecosystemsFire is a defining characteristic of many ecosystems worldwide, and, as the climate warms, both fire frequency and severity are expected to increase. In addition to the effects of smoke on the climate and human health, there are less apparent effects of fire on the terrestrial ecosystem. From alterations in the local soil properties to changes in the carbon budget as organic carbon is combusted into CO2 and pyrogenic carbon, fire is deeply impactful to the local landscape. The long-term climate implication of fire on the terrestrial carbon budget is a tension between carbon lost to the atmosphere as carbon dioxide and sequestered in the soil as recalcitrant pyrogenic carbon. Here we present a new model to simulate the interaction between ecosystem growth, decomposition, and fire on carbon dynamics. We find that the carbon lost to burned carbon dioxide will always be recovered, if there is any recalcitrant pyrogenic carbon generated by the fires. The time scale of this recovery, however, is highly variable and often not relevant to land managers. This model highlights key data gaps at the annual and decadal time scales. Quantifying and predicting the loss of soil, litter, and vegetation carbon in an individual fire event is a key unknown. Relatedly, the amount of pyrogenic carbon generated by fire events is another near-term data needed to better constrain this model. Finally, on the longer time scales, the degree of recalcitrancy of pyrogenic carbon is a critical unknown.
Daniel Fuka (VA Tech)Rapidly improving the spatial representation of soil properties using topographically derived initialization with a proposed workflow for new data integration
Topography exerts critical controls on many hydrologic, geomorphologic, biophysical, and forest fire processes. However, in modeling these systems, the current use of topographic data neglects opportunities to account for topographic controls on processes such as soil genesis, soil moisture distributions, and hydrological response; all factors that significantly characterize the post-fire effects and potential risks of the new landscape. In this presentation, we demonstrate a workflow that takes advantage of data brokering to combine the most recent topographic data and best available soil maps to increase the resolution and representational accuracy of spatial soil morphologic and hydrologic attributes: texture, depth, saturated conductivity, bulk density, porosity, and the water capacities at field and wilting point tensions. We show several proofs of concept and initial performance test the values of the topographically adjusted soil parameters against those from the NRCS SSURGO (Soil Survey Geographic database). Finally, we pose the potential for a quickly configurable opensource data brokering system (NSF BALTO) to be used to make available the most recently updated topographic and soils characteristics, so this workflow can rapidly re-characterize and increase the resolution of post-fire landscapes.
Dalia Kirschbaum (NASA GSFC)
Towards characterization of global post-fire debris flow hazardPost-fire debris flows commonly occur in the western United States, but the extent of this hazard is little known in other regions. These events occur when rain falls on the ground with little vegetative cover and hydrophobic soils—two common side effects of wildfire. The storms that trigger post-fire debris flows are typically high-intensity, short-duration events. Thus, a first step towards global modeling of this hazard is to evaluate the ability of GPM IMERG and other global precipitation data to detect these storms. The second step is to determine the effectiveness of MCD64 and other globally available predictors in identifying locations susceptible to debris flows. Finally, rainfall and other variables can be combined into a single global model of post-fire debris flow occurrence. This research can show both where post-fire debris flows are currently most probable, as well as where the historical impact has been greatest.
How to Prepare for this Session:PresentationsView Recording: https://youtu.be/I89om-kBYB0Takeaways- Modeling and detecting fires and fire impacts is changing (e.g. neural networks, carbon modeling) and needs to continue to improve
- There are many data needs to be able to operationalize post-fire debris flow and soil modeling
- Fires severely change ecosystems and soils and we do not really understand the exact changes yet, need more research in this area
