Agriculture and urbanization have fragmented landscapes and altered fire frequencies, thereby affecting seed dispersal and the abundance of fire-dependent species (Nowacki and Abrams 2008). However, actual climate change effects on the biota are uncertain, given lags in species migration, the longevity of trees, and the legacy of land-use practices both today and over past millennia (Thuiller et al. Here, modest shifts in climate may cause substantial shifts in the vegetation that will eventually occupy such sites. 2007).Ĭlimate change impacts may be particularly noticeable at ecotones with abrupt boundaries between contrasting vegetation types (e.g., Gosz 1992 Risser 1995). 1995 Schwilk and Keeley 2012), the substantial warming expected over the next century is predicted to have large effects on landscapes and species distributions (e.g., Bakkenes et al. Although concurrent changes in land use and fire regimes are often confounding factors in such studies (Archer et al. More recently, changes in plant phenology and distributions of species have been attributed to climate change (e.g., Menzel et al. Land-use change and the spread of exotic species have caused profound changes to the Earth's biota (Whitney 1994 Vitousek et al. We hypothesize that the differences between the future predictions from these two approaches are due in part to the inclusion of fire effects in MC1, and we highlight the importance of accounting for fire as managed by humans in assessing both historical species distributions and future climate change effects. This result contrasts with projections for ponderosa pine based on climatic niches, which suggest that its suitable habitat in the Black Hills will be greatly diminished by the middle of the 21st century. However, established ponderosa pine forests are relatively fire resistant, and areas that were initially wooded remained so over the 21st century for most of our future climate x fire management scenarios. Based on three downscaled general circulation model climate projections for the 21st century, we simulate greater frequencies of natural fire throughout the area due to substantial warming and, for two of the climate projections, lower relative humidity. Results show that fire frequency, as affected by humidity and temperature, is central to the simulation of historical prairies in the warmer lowlands versus woodlands in the cooler, moister highlands. For this purpose, we parameterized MC1 for ponderosa pine in the Black Hills, designating the revised model as MC1-WCNP. Here, we examine how the combination of climate and fire influence historical and future distributions of the ponderosa pine–prairie ecotone at the edge of the Black Hills in South Dakota, USA, as simulated by MC1, a dynamic global vegetation model that includes the effects of fire, climate, and atmospheric CO 2 concentration on vegetation dynamics. Natural and anthropogenic fires have shaped the distributions of many plant species, but their effects have seldom been included in future projections of species ranges. However, the mechanisms that would cause such shifts are uncertain.

Large shifts in species ranges have been predicted under future climate scenarios based primarily on niche-based species distribution models.

Ecotone fires