Introduction

Hi, I’m David McPherson and I’m doing research this summer with Charles Center funding.

The American chestnut used to be a dominant species of eastern forests in the US. It composed a significant portion of the canopy, and its nuts provided food for a variety of creatures, from rodents to humans. The introduction of the chestnut blight, which eliminated the nearly all canopy American chestnut trees, pre-dates modern forest ecology, and consequentially the significant impact the species had on the forest is not known. The chestnut is a flagship tree species, and for decades numerous groups have been trying to find ways to develop blight-resistant trees to reintroduce to the wild. For the reintroduction of blight-resistant trees to succeed, it is necessary to understand the ecology behind the chestnut. Some populations in New England have, so far, been spared the blight due to both isolation and the cold winter temperatures. While the blight has a presence in some populations, it has not yet been able to completely upset the ecology of these forests as it has done in warmer climates. This unique situation enables the modern study of forests containing chestnut trees.

Understanding the effects of biotic and abiotic factors on chestnut reproduction, spread, and juvenile growth is essential to ensuring the success of reintroduction efforts. Mathematical models backed by ecological research provide an effective way to combine and make sense of data. The goal of my research will be to help provide reintroduction efforts with the information needed to ensure the expensive blight-resistant trees have the greatest chance of survival. My first goal this summer is to continue the development of a matrix model for population growth and expand on previous modeling efforts in the Plant Ecology Lab by incorporating such factors as herbivory, canopy-openness, soil conditions, and inter- and intra-specific density. My second goal is to travel to the New England field sites (one in Maine and one in Vermont) with Dr. Dalgleish as a member of her field crew to collect another year of demographic data at these sites.

I have a complete background in the field I am researching. In high school I gained experience working with plants in the field while assisting a Smithsonian researcher. In college I took a course on ecology, and from it I gleaned the basics on the topic. I then joined the Plant Ecology Lab at William and Mary, where we have weekly discussions on different topics in plant ecology. We have covered this specific project in detail, and talked about more general issues facing chestnut trees. I have taken numerous math courses, including, most relevantly, linear algebra and introductory statistics. My computer science courses involved programming, which introduced me to the general use of computer languages. I have also met independently with my professor to go over population modeling both in general and using the computer program R.

In the beginning of the summer I will focus on developing and parameterizing a matrix model using the 2 years of data already collected from the field site. I will be working closely with another undergraduate who was involved with collecting the chestnut data last summer. For a few weeks in July I will return to the population we are modeling to continue data collection. I will use this data to extend and improve the model currently in development. I will also have the opportunity to collect a second year of data from a second population and begin working on developing a separate model that can be used to contrast with the current one.

My goal for this summer research session is to have a working model for the Maine site. Ultimately, I aim to publish the model with help from Dr. Dalgleish. I also aim to present the work at local and regional meetings including the Annual Meeting of the American Chestnut Foundation. Upon returning to campus this fall, I will begin model development for the Vermont site using data collected in July.

I have a strong interest in plant ecology, but with the hustle and bustle of school I have only skimmed the surface and not had an opportunity to really delve into the topic. With the work this summer I will not have distractions and pressing deadlines unrelated to this topic, and I will be able to focus solely on the work at hand. Chestnut trees, specifically, have a special place in my heart, because I remember collecting and playing with the nuts as a young child, but I rarely see them around anymore. It is exciting for me to be able to assist in the reintroduction of this magnificent tree.