## 1 Introduction  
Over the past several decades, increases in wildland fire frequency, size, and severity have had major influences on ecological, economic, and social systems [1,2]. Of the 26.8 million hectares that burned in eleven western US states between 1984 and 2011, 70.9% (19.0 million hectares) were located in grasslands and shrublands as recorded by the Monitoring Trends in Burn Severity (MTBS) project [3]. Despite the prevalence of fires in these western US shrubland/grassland ecosystems, relatively limited research has been done to assess the fire behavior characteristics of these ecosystems and the long-term shrubland/grassland changes that are occurring throughout the region. There is a pressing need to better assess and evaluate the changes of the shrubland/grassland ecosystems and their relationships with fire occurrence and risks [4]. Such assessment can provide managers with critical information for improved management in the shrubland/grassland ecosystems to maintain ecosystem sustainability and to help reduce the negative impacts of wildfires. The Landscape Fire and Resource Management Planning Tools Project (LANDFIRE) [5,6] was established in association with the National Fire Plan by the U.S. Department of Agriculture Forest Service and the Department of Interior. This landscape-scale fire, ecosystem, and fuel assessment project generates and distributes nationwide 30-meter-resolution data products for fire hazard reduction, incident planning and support, and resource management. The existing LANDFIRE database includes vegetation composition and structure, surface and canopy fuel characteristics, historical fire regimes, and ecosystem status. LANDFIRE provides the most recent nationally consistent and detailed reference conditions for the existing vegetation cover and fire fuel structures, and the data are relevant and accessible to land managers. While LANDFIRE data have many potential uses and applications, one known area of weakness relates to how LANDFIRE characterizes shrublands and grasslands. Some of the shrubland/grassland mapping and fuel characterization problems are a direct result of lack of field reference information, and LANDFIRE is very dependent upon the availability of accurate and current field information [5,7]. Shrublands and grasslands tend to have less readily available field information than forests, which tend to be relatively data rich. Another aspect of shrublands and grasslands that has been problematic for LANDFIRE relates to the intra- and interannual spectral, phenological, and ecological variability inherent to these systems. Shrubland/grassland ecosystems change much from year to year, and from season to season, thereby making it difficult to accurately characterize fire fuels for any one given point in time. The combination of (1) the lack of field information and (2) the complexity of fire fuel characteristics in these regions has made applications of LANDFIRE data in shrubland/grassland ecosystems challenging. LANDFIRE fuel data layers can be used for spatially explicit modeling of fire behavior and spread to support fire management decision making. Historically, the LANDFIRE fuel layers have been static, with periodic updates, but for the most part, the intra- and interannual variability in fuel loads have not been well represented. As discussed by [PERSON], et al. [8], the reasons for the difficulties in being able to effectively characterize shrublands and grasslands for fire applications are varied and many, but a large part of the problem revolves around the high degree of intra- and interannual variability in fuel characteristics in these areas, necessitating higher level understanding of the dynamics of these systems [8]. It is clear that more frequent observations will help to develop better understanding of the conditions that influence grassland and shrubland fuel characteristics and consequently wildland fire behavior and spread.