## 4 Conclusions  
This study produced two significant achievements. Accounting for both the effects of weather and site conditions to compare every pixel to its expected mature forest equivalent improves the utility and interpretation of time series remote sensing data by moving toward ecosystem succession and stress assessment. A data intensive (15,049 random unburned locations stratified across multiple years) regression tree model was robust to a wide range of weather and site conditions and predicted undisturbed boreal forest productivity (growing season integral of NDVI) using long-term site potential (combination of surface geology, climate, elevation, _etc._) and weather (R\({}^{2}\) = 0.53, \(p<0.0001\)).  
Our study produced two major findings. First, peak ecosystem performance and landscape diversity occurred in stands that are 30-40 years old. Second, minor increases in productivity for future undisturbed boreal forest are expected (5.6% by 2040 and 8.7% by 2070) and are anticipated to be related to an increasing deciduous forest species composition. Future projections are for mature boreal forest and do not include fire or other disturbances and further assume future Yukon River Basin boreal ecosystems will be redistribution or a subset of the current ones.  
This study is unique because it provides monitoring based on deviation from what mature boreal forest productivity should be given site and weather conditions, which de-trended for interannual variations related to weather conditions and facilitated post-fire succession tracking. This study advances knowledge and informs management and field studies by identifying areas at 250 m resolution that are likely to be resilient or susceptible to change with a warming climate. This information is important to decision making related to climate implications, feedback, mitigation, and adaptation at global scales [20] and can inform land managers and users (native Alaskans) making adaptive management decisions. Future applications would be facilitated by improved input data layers including improved weather, permafrost, soil texture, and soil organic layer maps. We hope to apply this approach to identify abnormal successional paths from recent and future fires, which may reflect long-term ecosystem shifts.  
This study was funded by the U.S. Geological Survey programs of LandCarbon, Climate and Land Use Research, and Development, and Climate Effects Network. We thank [PERSON] for use of their Yukon Flats biomass data and [PERSON] (USGS EROS) for reviewing an earlier version of this manuscript. The authors would like thank the Canada Centre for Remote Sensing and Environment Canada for facilitating data contributions from several federal and territorial governments, and [PERSON] and [PERSON] who assisted with data processing.  
[PERSON] was responsible for experimental design and theory, implementation of EPA analysis, and writing. [PERSON] analyzed EPA results, conducted literature research, prepared figures, and assisted with writing. [PERSON] supported EPA analysis, provision of input layers (particularly related to Canada), and revision reviews. [PERSON] contributed analysis scripting used in EPA modeling and mapping, Canadian input layers, and version reviews. [PERSON] prepared input layers, constructed the merged land cover product, and organized two workshops on the analysis of the EPA data sets. [PERSON] extended the EPA analysis through the years 2007 and 2008 and edited revisions.  
The authors declare no conflict of interest.