Sponsored Projects for Undergraduate Research

Project Description

            Euro-American activity in the post-settlement era of California brought about drastic changes to the climate, disturbance regime and forest structure of the state’s montane ecosystems. While the influence of colonialism is still present in neighboring Baja California, Mexico, its effect on Baja’s montane forests is less pronounced, making these systems an approximate reference system for Alta California’s conifer forests. This discrepancy provides an excellent opportunity to explore the effects of human influence on forests in the California – Northern Baja California region, which could aid managers and policymakers in both countries seeking to address restoration and fire-risk concerns.

            Forest demography, which describes the size and age structure of forests, affords a detailed framework with which to model changes in forest systems by incorporating an explicit time-element. However, the ability to reconstruct historic demographic trajectories in forests has long been limited by a lack of both data and appropriate statistical methodology. Recent advancements in the development of hierarchical integral projection models have taken care of the second concern, while our lab’s collection of a uniquely comprehensive dataset of tree-cores provides a remedy for the first. In a massive sampling effort, we collected, mounted and prepared over 3,000 tree cores from three four-hectare stands (two in the Sierra San Pedro Mártir in Baja California, Mexico, and one in the Eastern Sierra Nevada of Alta California).

By measuring and dating the rings in these cores we hope to reconstruct demographic histories for the three sites in order to estimate the growth, mortality and fecundity of trees in the study. We will then relate these estimates to reconstructed fire histories, as well as regional climate patterns in order to better understand how the relationships between them have changed over time. Finally, by comparing the relationships between fire, climate and demography in Baja California stands to those in the Alta California stand, we hope to contextualize the historic trajectory of these time-varying relationships within the divergent patterns of human influence in these two locations.

Number of Students Requested – 2

Undergraduates’ Role

            The undergraduates selected to participate in this project will measure and date the tree cores sampled from the three stands in the study. They will learn the basics of dendrochronology and tree morphology in order to identify ring characteristics and anomalies in the tree core samples. Students will learn to use the software CooRecorder to digitize and measure these samples. Finally, students will learn to employ cross-dating algorithms in R and the program COFECHA to build a complete database of the tree core samples. If interested, opportunities to continue working on the project in the statistical analysis phase may be available.

Undergraduates’ Qualifications

            Students who apply should be interested in ecology, climatology and/or forestry. Students must be independent, organized and motivated workers comfortable working with computers. Students with prior knowledge on tree morphology and forest ecology will be prioritized. Similarly, students with some experience in basic computer programming are preferred. However, this experience is not required, and interested students without a programming background are encouraged to apply.

Hours per Week:

            While the hours worked can be flexible, we prefer students who are willing to devote six or more hours per week to this project. Students who can afford less are still encouraged to apply provided they are explicit in their application about their time restrictions.