PhD Research at Aarhus University

For my PhD, I am using digital soil mapping techniques to determine bio-physical regions in Denmark. My project is embedded within Danish research and development project “ProvenanceDK”. The aim is to characterize terroir-like regional entities by integrating soil properties with topographic and landform attributes together with information on climate variation across Denmark. I am using machine learning, both supervised and unsupervised, with gridded and point data to characterize Denmark into different regions.

My work has three main components. The first is to combine soil, climate, and topography to generate physical regions that can be assessed for crop suitability or environmental risks. The second is to create a crop suitability map for winter wheat using random forest and compare to a previous winter wheat yield map based on a pedotransfer function. The third is to compare current spring barley yields to the productivity maps created in 1688 and 1844.

Terron Workflow

The first part of my work is based on creating terrons. Terrons are defined as areas similar in soil and landscape. There are two approaches to terron mapping. The first was proposed in 2005 by Carré and McBratney, using soil profile data, and the second was by Malone et al. in 2014, using gridded data. My work is to develop a workflow that will automate terron class creation using gridded data. I will post my manuscript and code once it has been accepted.

As I develop my project further, I will add more details on the two other components.

Master’s Research at the University of Idaho

The goal of my Master’s thesis was to understand how variation in habitat can promote species richness and trait diversity. The first objective of this project was to link how island ontogeny shapes the number of species found on islands. The second objective was to quantify the association between habitat features and variation in morphology and physiology of species. I am interested in using GIS techniques in biology to help with management decisions in conservation. To view my thesis, please click here.

Species Richness

By using the data available at the Charles Darwin Foundation Datazone, I could test the topographic complexity assumptions that are made in the General Dynamic Model (GDM) of Oceanic Island Biogeography. The assumption is that topographic complexity will follow a hump-shaped curve through an island’s ontogeny. I was testing to see if this assumption is true in the Galapagos and if topographic complexity is incorporated into the model, which measure of complexity should be used. Since there are many different ways to measure topographic complexity, I wanted to know if there is a single measure that should be used to model all taxonomic groups in the Galapagos or if each taxonomic group has a different measure depending on how each group interacts with the landscape.

Trait Diversity

To understand how trait diversity is linked to the habitat where species are found, a well-studied adaptive radiation of the Galapagos islands was used. The endemic land snails of the genus Naesiotus represent the most species rich adaptive radiation of the Galapagos islands with over 60 species currently described. Naesiotus inhabits most islands in the Galapagos from lower elevations that are hot and arid to higher elevations that are cool and humid. Along this environmental gradient, these species exhibit diverse shell sizes and shapes. Although work in this system using phylogenetically-controlled analyses has identified a strong link between shell morphology and ecology, a thorough study of physiological variation within and among species is needed to identify the proximate mechanisms and ultimate causes responsible for ecological diversification. I was linking morphological and physiological changes with environmental variation which will help in understanding why an adaptation would arise and why a lineage has diversified.

The word clouds above were generated from my manuscripts and thesis chapters. This page also has some of my favorite animal photos and a video I made on the fascinating things I saw while in the Galapagos. You can also watch this video on youtube by clicking here.