Complex Response of White Pines to Past Environmental Variability Increases Understanding of Future Vulnerability

Abstract

Ecological niche models predict plant responses to climate change by circumscribing species distributions within a multivariate environmental framework. Most projections based on modern bioclimatic correlations imply that high-elevation species are likely to be extirpated from their current ranges as a result of rising growing-season temperatures in the coming decades. Paleoecological data spanning the last 15,000 years from the Greater Yellowstone region describe the response of vegetation to past climate variability and suggest that white pines, a taxon of special concern in the region, have been surprisingly resilient to high summer temperature and fire activity in the past. Moreover, the fossil record suggests that winter conditions and biotic interactions have been critical limiting variables for high-elevation conifers in the past and will likely be so in the future. This long-term perspective offers insights on species responses to a broader range of climate and associated ecosystem changes than can be observed at present and should be part of resource management and conservation planning for the future.

Past vegetation dynamics in the Yellowstone region highlight the vulnerability of mountain systems to climate change

“…Differences in the spatial and temporal patterns of genera with similar climate tolerances (e.g. Picea and Abies ) as well as the dominance of P. contorta in central Yellowstone region attest to the role of disturbance, soil fertility and competition in shaping vegetation at the local scale (Iglesias et al., ; Krause & Whitlock, ).…”

“…Open, Parkland and Forest Cover) derived from the sequentially partitioning of the modern pollen dataset; and (c) SCDs between fossil pollen samples and the youngest sample of each record, which are interpreted as a proxy of the local vegetation trajectory. The pollen‐based vegetation reconstruction is compared with a published composite of six charcoal records from different elevations in the GYE (Iglesias et al., ) and July and January insolation anomalies to provide insights on past ecological changes in light of large‐scale changes in climate (Figure ).…”

Climate Change

“…In the greater Yellowstone ecosystem, regional analysis of charcoal records describe broad trends in climate, fire, and vegetation change over the past 15,000 years (Iglesias et al, 2015). These data indicate that highest fire activity in the region occurred between 12,000 and 10,000 cal year BP, when summers were warmer than today, winters were colder, and winter precipitation was generally high.…”

Complex Challenges of Maintaining Whitebark Pine in Greater Yellowstone under Climate Change: A Call for Innovative Research, Management, and Policy Approaches

“…This persistence of WBP in the GYE since the last glacial maximum suggests that the species can tolerate a much wider range of climatic variation than its current distribution would suggest, particularly under lower levels of competition from other tree species. A caveat of this study, however, is that pollen of WBP cannot be separated from the closely related limber pine (P. flexilis) that tolerates much warmer conditions than WBP and the presence of limber pine in GYE during the Holocene is poorly known [75].…”