PALEOECOLOGICAL INSIGHTS ON CONSERVATION OF BIODIVERSITY:A FOCUS ON SPECIES, ECOSYSTEMS, AND LANDSCAPES

Environmental changes of the Quaternary have driven changes in biodiversity at every level of organization from genetic variation within populations of individual species to gradients in composition of biotic communities and heterogeneity of vegetation mosaics across landscapes. In the southern Appalachian Mountains, increased seasonality of climate during the changeover from glacial to interglacial conditions in the late Pleistocene and Holocene resulted in landscape instability that fostered a fine‐grained, heterogeneous mosaic of habitats supporting a diverse biota. Ecotones between alpine, boreal, and temperate ecosystems in the Appalachians shifted dramatically through the Holocene in response to the passage of critical thresholds of temperature and changing disturbance regimes. Regional projections of future greenhouse‐gas‐induced climatic warming indicate that alpine tundra may be lost between 44° and 57° N and Picea rubens–Abies fraseri forests may become extinct in the southern Appalachians. Montane Picea rubens–Abies balsamea forests probably will be perpetuated between 44° and 49° N. Disjunct populations of alpine tundra species may persist below climatic treeline in small patches of open habitat. Biotic responses to late‐Quaternary environmental changes indicate that a primary conservation emphasis should be to predict the effects of changes in landscape‐level environmental processes on biodiversity.