Replication Data for: Ice age refugium shows potential of geohistorical data to guide modern conservation efforts

This repository contains the code and data required to replicate Figures 3, 4, S1, and S2 for the manuscript entitled \"Ice age refugium shows potential of geohistorical data to guide modern conservation efforts.\" Also contains the code required to perform the Monte Carlo simulation used to calculate the probability of a refugium explaining the regional decline and recovery in spruce incidence. Manuscript summary: Many biologists regard refugia as locations that shelter a population during an environmental crisis, thus facilitating post-crisis ecological recovery. However, identifying refugia based on short-term contraction and survivorship alone is problematic as this approach fails to account for whether the species survives and recovers in the long-term. Protecting refugia that are unstable in the long-term could lead to wasted conservation efforts and the species’ extinction. Here, we present a novel method for identifying geohistorical refugia that emphasizes a population’s long-term success and post-crisis recovery. To test this method’s utility, we present a case-study using pollen data for three ecologically distinct plant taxa from lake cores over the past 20 kyr in northern Alaska, USA. Using Monte Carlo methods, we found a statistically significant decrease in spruce incidence across the study region between 13.0 – 10.0 ka. During this interval, spruce persisted at relatively high abundance in one locality that may have provided the cool, humid conditions necessary for spruce survival during an interval of warmer, drier regional climate. This locality acted as the center for post-crisis re-expansion after the warm, dry conditions passed, indicating that this location was likely a refugium. If successful geohistorical refugia can be identified, subsequent analyses should aim to identify which environmental conditions allowed the population to survive within the refugium and re-expand after the crisis, thus providing critical information for policymakers when identifying locations for successful, long-term protected areas in the face of the ongoing biodiversity crisis.