Digital Commons Network^™

A Feasibility Study: Forest Carbon Stocks And Stock Change Of The White Mountain National Forest, Erica Jane Cate

Master's Theses and Capstones

Interest has heightened for forest managers to account for the impacts of management activities on forest carbon sequestration. This study was designed to assess the feasibility of developing estimates of WMNF forest carbon based on the available information. The yield curves, inventory data and resulting carbon projections were dependent on a number of assumptions and subject to various sources of error and bias. Thus, they should not be relied on as definitive estimates and forecasts, or used as a basis for policy recommendations. Under the specific approaches used in this study, forest carbon stocks appear to be accumulating in the …

Effects Of Physical And Chemical Disturbance On Stream Ecosystem Structure And Function, Elena M. Traister

Doctoral Dissertations

A variety of natural and anthropogenic disturbances influence the structure and function of stream ecosystems. While past investigations have focused on the response of community indicators to stream disturbances, functional indicators may also be helpful for assessing stream ecosystem health. To date, few studies have compared the response of structural and functional indicators to ecosystem-level disturbances. I separately measured the effects of long-term acidification, a large-scale avulsion, and the individual and combined effects of physical streambed disturbance and altered refugia availability on stream structural and functional metrics.

I found that acidification was associated with changes in macroinvertebrate communities including reduced …

Hydrologic And Nutrient Dynamics In An Agriculturally Influenced New England Floodplain, Michelle Galvin

Master's Theses and Capstones

Non point-source pollution from agricultural activity is a major cause of water quality degradation. In particular, nutrient loading can lead to eutrophication and related anoxia in rivers, streams and lakes. Floodplains adjacent to these water bodies are sites of active nutrient cycling that can mediate the flux of nutrients to and from these water bodies. This study examines the hydrologic and nutrient dynamics of an agriculturally-influenced creek and floodplain in Lee, New Hampshire. Chemical mixing models were used to assess cycling of nutrients in response to flooding. The floodplain acted primarily as a sink for phosphate (PO43-), ammonium (NH4+) and …

Identifying Temporal Patterns And Controlling Factors In Methane Ebullition At Sallie's Fen, A Temperate Peatland Site, Using Automated Chambers, Jordan Goodrich

Master's Theses and Capstones

Despite leading to a potentially significant positive climate feedback, the processes controlling wetland methane fluxes remain relatively poorly understood. Automated chambers were employed in a temperate peatland site to quantify the timing and magnitude of methane ebullition (bubbling), one of the three pathways for wetland methane flux. The resulting datasets offer high temporal coverage of both components of this flux pathway, allowing for the first analysis of ebullition variability on seasonal, synoptic and diel timescales. The seasonal peak in ebullition occurred in August, likely due to high methane production rates and low methane solubility, both driven by temperature. Synoptic scale …

Modeling Permafrost Stability In Peatlands With Climate Change And Disturbance, Claire Treat

Master's Theses and Capstones

Boreal and arctic regions are predicted to warm faster and more severely than temperate latitudes. They contain large stocks of below- ground soil carbon in peatlands and frozen soil, and the flux of the soil C to the atmosphere may be a strong feedback to climate change.

Increases in air temperature due to climate change will increase surface soil temperatures, soil temperatures at depth, active layer depths, and growing season length, but not degrade permafrost by 2100 at this site. Both wildfire and climate change increase active layer depths by 25 cm, but effects of wildfire diminish following vegetation recovery.

Variation In Foliar Nitrogen And Albedo In Response To Nitrogen Fertilization And Elevated Carbon Dioxide, Haley F. Wicklein

Master's Theses and Capstones

It has recently been demonstrated that foliar nitrogen is positively correlated with surface albedo over a broad range of plant functional types. However, the mechanism(s) driving the nitrogen-albedo relationship remain elusive. This study investigated leaf spectral properties from three deciduous species subjected to either nitrogen or CO2 fertilization and compared results to measured chemical and structural properties. We measured reflectance and transmittance, foliar nitrogen, leaf mass per unit area, water content, and d13C values for stacks of 1, 2, 4, and 8 leaves. Nitrogen was the best predictor of leaf-level albedo of the traits that we measured. There were no …