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Analyses of pollen and spore distribution in samples taken in close stratigraphic succession from several sections of the Neogene Succor Creek, Stinking Water, and Trapper Creek floras indicate that the source-vegetation mosaic at each site was in a state of ecological disequilibrium. All these floras are preserved in volcaniclastic sediments, and in each case the presence of fossiliferous strata is closely linked in both space and time with local eruptive activity. The exposed stratigraphic sections appear to represent relatively short periods of time, probably less than 10,000 yr, excluding unrecognized diastems. In all cases, most of the time represented in the studied sections records successional vegetation rather than a mosaic of community types in equilibrium with the prevailing paleoclimate. In most cases, the ecological dynamics can be related to the disturbance or destruction of forests by local volcanic activity and/or fire, followed by distinctive serai stages, barring further disturbance, leading to the reestablishment of a diverse forest-community mosaic. Many of the megafossil collections from these floras have lacked sufficient stratigraphic control, and most represent a single serai stage or a mélange of serai stages. Reconstructing the megafossil assemblages that correspond to specific stages in the recovery continuum is rarely possible.

Pollen spectra characteristic of minimally disturbed communities are rare. Of the three floras studied, the Stinking Water represents the lowest paleoelevation and/or highest paleotemperature of forests dominated by broadleaved taxa throughout the area. Conifer stands were rare and confined to local topographic highs. The Succor Creek area supported a diverse array of broadleaved-dominated forests in the lowlands and conifer-dominated forests on adjacent low slopes, suggesting a cool but equable paleoclimate. The southern part of the Succor Creek area was probably higher and topographically more diverse than the northern part of the area. The Trapper Creek region was higher and/or cooler than the other sites and was dominated by coniferous forest. Broadleaved-dominated communities in the Trapper Creek area were significant only in the recovery intervals following disturbance.

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