Variability in plant community dynamics ultimately determines vegetation mosaics, stand structures, and species composition. Successional trajectories and plant growth are influenced by a number of factors including land use, fire, nonnative species, edaphic (soil) conditions, and climatic variability. Interactions among these factors can lead to alternative successional pathways and can push systems beyond ecological thresholds from which they may not recover without intensive human intervention. Dynamic vegetation traits in turn dictate fuel types, fuel loadings, and fuel continuity across landscapes. Fuel and fire models can be used to predict fire danger, fire behavior, and fire effects across landscapes, but poorly measured and dynamic fuelbed mosaics make these tasks difficult. Thus, a key to understanding and managing fire in large landscapes is to develop adequate spatial models of successional change and plant productivity that are coupled to quantitative measures of fuels. Sagebrush shrubland ecosystems in the Great Basin are a prime example of altered successional trajectories and dynamic fuel conditions. Although fire is a natural disturbance in sagebrush, post-fire environments are highly susceptible to the invasive plant-fire regime cycle. After fire, native shrub-steppe plants are often slow to regenerate, whereas nonnative annuals, especially cheatgrass (Bromus tectorum) and medusahead (Taeniatherum caput-medusae), can establish quickly and suppress native species growth and recolonization. Once fire-prone annuals become established, fire occurrence increases and further promotes nonnative dominance. The invasive plant-fire regime cycle also alters nutrient and hydrologic cycles, pushing ecosystems beyond ecological thresholds toward steady-state, fire-prone, nonnative communities. These changes affect millions of hectares in the Great Basin and increase fire risk, decrease biodiversity, degrade rangeland resources, and increase soil erosion. In many sagebrush landscapes, poorly quantified or constantly changing plant communities and fuel conditions hinder attempts by land managers to predict and control fire behavior, restore native communities, and provide ecosystem services. We propose to investigate and quantify the influence of land use (i.e. grazing), nonnative species, and altered fire regimes on successional pathways and associated fuel loads in Great Basin sagebrush ecosystems. The overarching goal of the proposed study is to develop an approach to better quantify and predict fuel loads and the effects of fuels manipulations in sagebrush habitats. To accomplish this goal we will address three primary questions: 1) What are current fuel loads along successional/invasion gradients in sagebrush ecological sites on the NCA focal area and throughout the Great Basin? 2) How do fuel reduction treatments and grazing influence fuels in invaded areas formerly dominated by sagebrush? 3) What are the fine-scale spatial patterns of fuels across landscapes and how can management actions be used to alter these patterns? We will use an integrated combination of stratified random field-sampling, experimental manipulation, and remote sensing analysis to achieve the following objectives: 1) develop growth and successional models coupled with fuel loadings for native and nonnative community types; 2) determine the influence of restoration treatments on fuel loads in highly degraded sagebrush landscapes and; 3) develop a spatially-explicit, predictive fuel load model that uses our successional models, field-sampled fuels data, and high-resolution, remotely-sensed data to characterize and quantify fuel loads and fuel patterns (e.g., continuity) across large landscapes. Successional models will be developed using existing data from an ongoing JFSP-funded project spanning the entire Great Basin (JFSP-Project ID:09-S-02-1) to infer comprehensive fuel conditions along a continuum of intact and degraded sagebrush.