There is the potential for a positive feedback to climate from changes in portions of the circumpolar taiga-tundra ecotone (TTE). Rapid warming has put the TTE in northern Siberia at the leading edge of such change, where recent observations suggest shifts in vegetation structure that are subtle but certain, and which vary widely based on site conditions. An understanding of how current spaceborne remote sensing tools characterize TTE vegetation structure in Siberia at fine scales is needed in light of observed changes and the central role of TTE vegetation structure patterns in determining ecological processes in the HNL and global change scenarios. The goal of this research is to evaluate the uncertainty of current and planned spaceborne remote sensing for monitoring vegetation structure across sparse forest gradients, integrate spaceborne measurements of vegetation characteristics in a data fusion approach, and apply this approach to evaluate forest patch height and its uncertainty within the TTE of northern Siberia. This uncertainty is examined in light of a conceptual model of regional vegetation structure to assess the potential of spaceborne maps for depicting TTE patterns and TTE forest structure vulnerability.