Quantifying the Effects of Topographic Aspect on Water Content and Temperature in Fine Surface Fuel. Nyman, P., Metzen, D., Noske, P. J., Lane, P. N. J., & Sheridan, G. J. 24(8):1129+.
Quantifying the Effects of Topographic Aspect on Water Content and Temperature in Fine Surface Fuel [link]Paper  doi  abstract   bibtex   
This study quantifies the effects of topographic aspect on surface fine fuel moisture content (FFMC) in order to better represent landscape-scale variability in fire risk. Surface FFMC in a eucalypt forest was measured from December to May (180 days) on different aspects using a novel method for in situ monitoring of moisture content (GWClit) and temperature (Tlit) in litter. Daily mean GWClit varied systematically with aspect. North (0.07 ≤ GWClit ≤ 1.30 kg kg-1) and south (0.11 ≤ GWClit ≤ 1.83 kg kg-1) aspects were driest and wettest respectively, whereas east and west were somewhere in between. On the warmest day (38.9°C), the maximum Tlit on north (43.7°C) and south (29.8°C) aspects differed by 13.9°C. Aspect-driven variation in Tlit and GWClit is exacerbated by vegetation, which increases markedly in density with decreasing solar exposure. GWClit was below fibre saturation point ($<$0.35 kg kg-1) on 49 and 128 days on south and north aspects, respectively, demonstrating that fuels beds are often in different stages of drying and therefore subject to different hydrological processes depending on landscape position. This terrain-related variability in moisture dynamics strongly affects the spatial connectivity of fuels, and may be more important for predicting landscape-scale burn outcomes than sub-daily fluctuations at a point. [Excerpt: Conclusion] The study shows that spatial variation in surface FFMC at small scales (hundreds of metres) can be extremely large due to variation in solar exposure and aspect-driven differences in soil and vegetation properties. At the scale of bushfires the terrain-related variability in litter moisture influences the connectivity of fuels and may override the importance of small sub-daily fluctuations at a point. This issue of spatial variability in complex terrain represents an important area for future research that will complement recent advances in process-based modelling of fuel moisture. Key challenges for the future include: [::] untangling the effects of vegetation and slope orientation on solar radiation and litter temperature [::] linking vegetation structure and its effects on radiation to landscape metrics such as aridity and drainage position that drive ecosystem heterogeneity [::] developing and refining methods for in situ monitoring of moisture content in litter. [\n] [...]
@article{nymanQuantifyingEffectsTopographic2015,
  title = {Quantifying the Effects of Topographic Aspect on Water Content and Temperature in Fine Surface Fuel},
  author = {Nyman, Petter and Metzen, Daniel and Noske, Philip J. and Lane, Patrick N. J. and Sheridan, Gary J.},
  date = {2015},
  journaltitle = {International Journal of Wildland Fire},
  volume = {24},
  pages = {1129+},
  issn = {1049-8001},
  doi = {10.1071/wf14195},
  url = {https://doi.org/10.1071/wf14195},
  abstract = {This study quantifies the effects of topographic aspect on surface fine fuel moisture content (FFMC) in order to better represent landscape-scale variability in fire risk. Surface FFMC in a eucalypt forest was measured from December to May (180 days) on different aspects using a novel method for in situ monitoring of moisture content (GWClit) and temperature (Tlit) in litter. Daily mean GWClit varied systematically with aspect. North (0.07 ≤ GWClit ≤ 1.30 kg kg-1) and south (0.11 ≤ GWClit ≤ 1.83 kg kg-1) aspects were driest and wettest respectively, whereas east and west were somewhere in between. On the warmest day (38.9°C), the maximum Tlit on north (43.7°C) and south (29.8°C) aspects differed by 13.9°C. Aspect-driven variation in Tlit and GWClit is exacerbated by vegetation, which increases markedly in density with decreasing solar exposure. GWClit was below fibre saturation point ({$<$}0.35 kg kg-1) on 49 and 128 days on south and north aspects, respectively, demonstrating that fuels beds are often in different stages of drying and therefore subject to different hydrological processes depending on landscape position. This terrain-related variability in moisture dynamics strongly affects the spatial connectivity of fuels, and may be more important for predicting landscape-scale burn outcomes than sub-daily fluctuations at a point.

[Excerpt: Conclusion]

The study shows that spatial variation in surface FFMC at small scales (hundreds of metres) can be extremely large due to variation in solar exposure and aspect-driven differences in soil and vegetation properties. At the scale of bushfires the terrain-related variability in litter moisture influences the connectivity of fuels and may override the importance of small sub-daily fluctuations at a point. This issue of spatial variability in complex terrain represents an important area for future research that will complement recent advances in process-based modelling of fuel moisture. Key challenges for the future include:

[::] untangling the effects of vegetation and slope orientation on solar radiation and litter temperature

[::] linking vegetation structure and its effects on radiation to landscape metrics such as aridity and drainage position that drive ecosystem heterogeneity

[::] developing and refining methods for in situ monitoring of moisture content in litter.

[\textbackslash n] [...]},
  keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-14073948,~to-add-doi-URL,australia,disturbances,fine-fuel-moisture-content,forest-fires,solar-radiation,temperature,topography,wildfires},
  number = {8}
}
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