The occurrence, spatial distribution, and ecological importance of large trees--say, the top 1% by diameter--are infrequently quantified, as these trees are by definition rare and usually difficult to study. Here Lutz et al. report establishing the permanent Yosemite Forest Dynamics Plot (YFDP) in an old-growth conifer forest. In this >25 ha plot they measured biomass and spatial patterns of trees with diameters of at least 1 m, and found that these giants dominated aboveground biomass, and their spatial pattern differed from that of smaller trees. Traditional theories of self-thinning and competition could not satisfactorily explain the occurrence of the large trees. This--ecosystems where a large proportion of ecosystem services are performed by a few large trees--has significant implications for forest management. Lutz and colleagues' YFDP provides a strong foundation for future exploration of these implications.