Climate change puts the invasive Japanese honeysuckle (Lonicera japonica) on the move in the southern forestlands of the United States

Abstract

Invasions of nonnative species have multiple implications, including modification of biogeochemical cycles, inhibition of natural regeneration of native species, and loss of ecosystem biodiversity and productivity. Japanese honeysuckle (Lonicera japonica Thunb.) is a vigorous invader of the southern forestlands of the United States (U.S.). Our objectives were to document changes in the distribution of Japanese honeysuckle since the turn of the century, identify climatic variables correlated with its successful invasion, and project its potential future distribution under climate change. To accomplish this, we analyzed the most recent U.S. Forest Service field measurements of Japanese honeysuckle in the southern U.S. Our analysis indicated that the number of sampled plots invaded by Japanese honeysuckle from 2009 to 2017 increased by approximately 53% compared to plots sampled from 2000 to 2008, and the mean percent coverage of Japanese honeysuckle in sampled plots increased significantly. Results of boosted regression tree analysis indicated that probability of invasion was correlated with six climatic variables, including annual precipitation, annual mean temperature, max temperature of warmest month, mean diurnal range, temperature annual range, and isothermality. The states projected to be most at risk to invasion under the historical climate were Kentucky, Arkansas, Tennessee, North Carolina, Mississippi, Alabama, Georgia, and South Carolina. Future projections imply a northward shift of predominant species presence, with the most likely affected states being Kentucky, Virginia, Tennessee, North Carolina, Alabama, and Georgia. Our model provides important insights into the management of Japanese honeysuckle in the southern forestlands of the U.S. By identifying current and potential future high-risk and low-risk areas, our results can aid forest managers in developing long term monitoring and control strategies for effectively slowing Japanese honeysuckle range expansion and mitigating its effects.