Environmental Studies

Lauren Sanchez ‘11: Changes in Leaf Area Index (LAI) due to Ice Storm Damage at Harvard Forest

Discuss this project in MiddLab
Session: Slow Growth- MBH 216 at 10:45 a.m. from the Undergraduate Research Spring Symposium
Faculty Sponsor: Steve Trombulak, Biology
Major: Enviromental Studies and Biology
Research Support: US Department of Energy

Terrestrial ecosystems play an integral role in the global carbon balance, potentially functioning as carbon sinks that fluctuate through time and seasonal changes. The net ecosystem exchange of these ecosystems has been heavily studied at the Harvard Forest Environmental Measurements Site (HFEMS) and has shown an increase in carbon sequestration over the past two decades. My study was conducted to analyze various impacts of the ice storm that struck New England in December 2008 with respect to the forest carbon flux. Several methods, including the eddy covariance technique, measuring downed woody biomass, and determining leaf area index (LAI) values, were used to evaluate and quantify the ice storm impacts. Several significant relationships were found in changes in LAI values, highlighting the importance of these measurements and analyses. The implications of these results also emphasize the importance of these forest measurements, given their role in the global carbon cycle.

Chris Free ‘10: The Population-level Impact of Density-dependent Seedling Mortality of Big-leaf Mahogany (Swietenia macrophylla)

Discuss this project in MiddLab
Session: Slow Growth- MBH 216 at 9:45 a.m. from the Undergraduate Research Spring Symposium
Faculty Sponsor: Matt Landis, Biology
Major: Environmental Studies/Biology
Research Support: Senior Work Fund

A high mortality of seeds and seedlings has been documented in areas of high conspecific adult density as a result of increased predation and disease. Although this phenomenon has received significant attention in the scientific literature, the long-term evolutionary and ecological impact of density-dependent seedling mortality remains poorly understood. The purpose of the present study is to determine the population-level impact of density-dependent seedling mortality on heavily exploited big-leaf mahogany (Swietenia macrophylla). The study was conducted by developing a spatially explicit individual-based model to examine the population size and distribution differences in mahogany populations grown with and without density-dependent seedling mortality. The heavy exploitation and threatened status of big-leaf mahogany highlight the importance of understanding density-dependent interactions in the develo p.m.ent of more robust predictive models and management plans.