My Research

Master's Research

During my master’s research, I collected vegetation and forest structure data on 360 plots in the Big River Watershed and surrounding regions within Mendocino County, California in 2007. I measured dominance, density, frequency, and diversity of species in naturally regenerating coast redwood forests of different stand age following clearcut timber harvest and compared those results to vegetation surveys I conducted in coast redwood old-growth stands in the same region. I used ANOVA and regression analyses to demonstrate that several stand and understory parameters, including tree density, canopy cover, and understory richness, statistically approached old-growth levels without human intervention. I found significantly fewer exotic species in older stands, allowing native plant species to dominate. The findings of this project suggest restoration within regenerating redwood communities of the Big River Watershed may benefit from allowing natural succession.

Doctoral Research

For my dissertation, I researched edge effects over space and time on an old-growth tract in Upper Michigan, the Sylvania Wilderness Area. Spatially, I used 1.5 km vegetation transects that crossed the Sylvania Wilderness border. Temporally, I tracked microfossil changes in high-resolution (sub-decadal), freeze-cored paleorecords of the last 300 years from lakes that varied in disturbance history relative to Sylvania’s border. To test the spatial edge effect, I collaborated with statisticians to develop a change-point analysis using generalized linear mixed models (see https://github.com/kkhmichels/edgeeffect). To test the temporal edge effect, I worked with statisticians to develop a time series change point analysis using the third derivative (the “jerk”). I found spatial edge effects up to 625 m into the Sylvania Wilderness - the farthest edge effects documented in this region. Paleorecords showed that wilderness lakes are less affected by disturbances than non-wilderness lakes. I also noted strong responses in specific taxa - particularly in dinoflagellate cysts and aquatic taxa such as Isoetes - following disturbance. Effects from disturbances manifested quickly (within 10 years) and had a long-lasting effect on aquatic taxa (minimum of 45 years). The results of my dissertation suggest implementing a minimum 500 m buffer zone around land use disturbances, applying high-resolution sampling to proximate lakes, and tracking dinocyst abundance may help sustain long-term ecosystem trajectories.