Long-term patterns of biodiversity in the Northern Rocky Mountains: Landscape dynamics, conservation paleobiology, and historical ecology

Background/Question/Methods

Climate change and human land use in the Northern Rocky Mountains have influenced long-term patterns of biodiversity.  Processes leading to environmental change in this region are linked to significant questions related to global change, including species introduction and extinction, land use, and conservation policies. Evidence of late Quaternary environmental change prior to and since the presence of humans can be used in attempts to distinguish natural environmental variability from human (anthropogenic) impacts, in addition to evaluating the ways human activities are directly or indirectly linked to changes in the environment.  This study examines long-term patterns of biodiversity connected with landscape change and human activity in mountain ecosystems using an interdisciplinary environmental studies approach.  It integrates data from paleobiology, geoarchaeology, and historical ecology.  Methods included the collection of Quaternary fossils (mostly vertebrate remains) and artifacts from stratigraphic sequences, geomorphic field studies, and the use of historical and survey records.   

Results/Conclusions

Research results document changes in landscape and biotic communities during the late Quaternary.  Faunal assemblages dated by radiocarbon to before 10,000 years ago (the Younger Dryas or earlier) from Centennial Valley, Blacktail Cave, Indian Creek, MacHaffie, Sun River, and Sheep Rock Springs in Montana contain a mixture of extinct and extant fauna.  While demonstrating the long-term presence of some faunal elements, there is also evidence for the restructuring of biotic communities after the Younger Dryas.  During the late Pleistocene and for most of the Holocene, the temporal and spatial distribution of biotic communities appears to have been primarily the result of climate change.  Human resource use was initially connected with hunting and gathering (including the use of fire).  The intensity of human influence on biodiversity increased during the late Holocene.  During the 1800s long-term changes in landform processes and biodiversity resulted from human activities such as beaver trapping, mining, logging, grazing, agriculture, and changing settlement patterns.  For instance, in Idaho's Boise River watershed, management strategies initiated since the early 1900s, such as the reintroduction of extirpated ungulates (wapiti, Cervus elaphus) and carnivores (wolf, Canis lupus), have affected biodiversity. The Northern Rocky Mountains presently contain wildland-urban interface areas where human activities are influenced by the geoecologic setting, and intensification of human land use has contributed to environmental change.  Thus, changing patterns of biodiversity appear to be an outcome of long-term landscape dynamics linked to climate change and land use.