Long‐term demography and spatial genetic structure reveal mechanisms of Sassafras albidum population persistence through clonality

PREMISE: Vegetative regeneration is a key mechanism of woody plant persistence in forest ecosystems, and the coupled roles of basal sprouting and clonal growth in shaping long-term population dynamics have been understudied. Basal sprouting replaces stems at fixed ramet locations, whereas clonal growth via root suckering produces spatially distinct ramets that promote genet-level persistence across space. Sassafras albidum, a clonal understory tree native to eastern North America, employs both mechanisms, making it an excellent system for evaluating how sprouting and clonality interact to structure populations. METHODS: We combined over two decades of demographic data with spatially explicit microsatellite analyses to examine population structure, spatial genetic organization, and persistence mechanisms in an upland oak-hickory forest on the Cumberland Plateau, Tennessee. RESULTS: . Clonal richness was low, indicating that most ramets were derived from clonal growth, yet clonal dominance was moderate to low, reflecting extensive intermingling of genets. Short and tall stems were spatially clustered and persistent through time, whereas intermediate stems were spatially and temporally unstable, revealing a demographic bottleneck. Genets differed markedly in their representation across size classes, indicating asynchronous demographic trajectories. CONCLUSIONS: We propose that the combined effects of basal sprouting and clonal growth generate persistent regenerative ramet locations, allowing genets to maintain advance regeneration across heterogeneous environments. These processes decouple stem turnover from genet turnover and facilitate long-term persistence in resource-poor upland forests.