Nathalie Chardon

Ph.D Student

My research focuses on what determines species range limits and how such geographic distributions respond to climatic changes and other human impacts. I am currently studying populations of the arctic/alpine cushion plant Silene acaulis (Carophyllaceae) across portions of its range in the North American Rocky Mountains and the European Alps in order to answer questions about its range limits. Specifically, I am interested in the effect of disturbance on the elevational range limits of S. acaulis, and how such effects interact with regional climate, microhabitat climate, and position within the range. I aim to discern if disturbance, by alleviating biotic competition or compounding the effects of harsh alpine climate, expands or constrains the elevational range of S. acaulis. Using the demography dataset for the species from Drs. Daniel Doak and William Morris (Duke University), I am able infer population performance across a wide spectrum of this species’ range with plant size structure surveys. This approach allows me to understand the effect of disturbance on a population-level scale, and how this varies within and between the North American and European continents.

In an effort to geographically map the distribution of S. acaulis with the help of the public, I worked with the Computer Science department and INSTAAR at the University of Colorado, Boulder to design a smart phone app. This app can recognize S. acaulis via a picture taken by the user, and GPS location as well as the identifying picture are uploaded to a server. The app also has a useful alpine plant field guide for the flora on Niwot Ridge LTER. We launched this citizen science project in Spring 2015, and this app is free for download on

Before starting my graduate studies, I worked in California montane ecosystems, under the supervision of Dr. David Ackerly and Dr. William Cornwell in the Ackerly lab (University of California, Berkeley) where I studied the geographic and climatic limits of Coulter pines (Pinus coulteri). I also worked for the USDA Forest Service in Nevada, conducting endangered plant surveys in proposed recreation areas throughout the Great Basin and the Sierra Nevada Mountains. In Montana, I worked in riparian ecosystems quantifying the effects of ungulate grazing on stream bank flora as part of a long-term project focused on restoring endangered cutthroat and bullhead trout habitat.