The history of widespread decrease in oak dominance exemplified in a grassland-forest landscape.

摘要: Regionally-distinctive open oak forest ecosystems have been replaced either by intensive agriculture and grazing fields or denser forests throughout eastern North America Europe. To quantify changes in tree communities density the Missouri Plains, a grassland–forest landscape, we used historical surveys from 1815 to 1864 current 2004 2008. estimate for communities, Morisita plotless estimator applied corrections surveyor bias. forests, Random Forests, an ensemble regression method, predict densities known values at plots using terrain soil predictors. Oak species decreased 62% of composition 30% black white oaks historically were dominant across 93% landscape currently 42% landscape. Current was approximately two times greater than densities, demonstrating loss savanna woodlands transition dense structure. Average diameters smaller past, but mean basal area stocking remained similar over time because increase forests. Nevertheless, there spatial differences; along rivers increased away rivers. are being other replacement range Quercus. Long-term commitment combinations prescribed burning silvicultural prescriptions more xeric sites may be necessary recruitment. Restoration is time-sensitive issue restoration will become increasingly costly as lost overstory surrounding matrix becomes dominated non-oak species.