Abstract
For this study, we characterized the dependence of fire counts (FCs) on soil moisture (SM) at global and sub-global scales using 15 years of remote sensing data. We argue that this mathematical relationship serves as an effective way to predict fire because it is a proxy for the semi-quantitative fire–productivity relationship that describes the tradeoff between fuel availability and climate as constraints on fire activity. We partitioned the globe into land-use and land-cover (LULC) categories of forest, grass, cropland, and pasture to investigate how the fire–soil moisture (fire–SM) behavior varies as a function of LULC. We also partitioned the globe into four broadly defined biomes (Boreal, Grassland-Savanna, Temperate, and Tropical) to study the dependence of fire–SM behavior on LULC across those biomes. The forest and grass LULC fire–SM curves are qualitatively similar to the fire–productivity relationship with a peak in fire activity at intermediate SM, a steep decline in fire activity at low SM (productivity constraint), and gradual decline as SM increases (climate constraint), but our analysis highlights how forests and grasses differ across biomes as well. Pasture and cropland LULC are a distinctly human use of the landscape, and fires detected on those LULC types include intentional fires. Cropland fire–SM curves are similar to those for grass LULC, but pasture fires are evident at higher SM values than other LULC. This suggests a departure from the expected climate constraint when burning is happening at non-optimal flammability conditions. Using over a decade of remote sensing data, our results show that quantifying fires relative to a single physical climate variable (soil moisture) is possible on both cultivated and uncultivated landscapes. Linking fire to observable soil moisture conditions for different land-cover types has important applications in fire management and fire modeling.
Highlights
Present day fires burn 350–450 million hectares globally per year [1,2], and release about2.5 petagrams of carbon into the atmosphere annually [3]
We suggest that the fire–soil moisture relationships we derive are analogous to the fire–productivity relationship [22,25,26], and evaluate how the fire–SM relationship varies across land-use and land-cover (LULC) in large sub-regions of the globe
We attempted to understand whether the fire–productivity relationship [22,25,26] is evident when studying 15 years of remotely sensed monthly fire counts (FCs) and near-surface soil moisture (SM) at the global scale, arguing that SM itself should reflect both fuel and climate constraints on fire activity
Summary
Present day fires burn 350–450 million hectares globally per year [1,2], and release about2.5 petagrams of carbon into the atmosphere annually [3]. Fire models strive to simulate the spatial and temporal distribution of global fire by modeling the dependence of fire occurrence and spread on the underlying environmental variables [4,5,6], while observationally based data from satellites, paleoproxies, and historical records inform how we understand interactions among fire, climate, and human activity and help to refine approaches within fire models [7,8]. (e.g., [4,15,16,17,18,19,20]), precipitation [21], temperature (e.g., [4,14,22,23,24]), and net primary production (NPP) [4,22,24,25] To varying degrees, these environmental factors determine the combustibility and fuel load of any landscape. In the classical approach to fire science, an ignition source either in the form of lightning or a human (combined with the environmental factors) is required to generate a fire start
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
