The hydraulic architecture of parallel veined monocots is fundamentally different from the branched networks of dicot leaves. The functional significance of this difference on leaf level gas exchange is not well understood. In order to investigate how the hydraulic architecture of monocots affect gas exchange we measured the axial hydraulic conductivity and leaf level gas exchange from the base to tip of 7 grass species. Stomatal conductance (g_s) and photosynthesis (A) increased but hydraulic conductivity (K_h) declined along the length of the blade.

Coastal bays, which are typically shallow, located in the photic zone, and have little freshwater input, respond differently to nutrient enrichment than deeper estuaries. Because of the diversity of benthic and pelagic autotrophs they support, coastal bays are capable of modulating the effects of nutrient enrichment, derived from both allochthonous and autochthonous sources. We describe a study performed in Hog Island Bay, Virginia, located along an eutrophication gradient on the Delmarva Peninsula, to determine sources, sinks, and fates of nitrogen (N).

We are in the process of developing a Calculus for the LIfe Sciences to serve biology majors at our institution. We have begun developing Excel labs and homework assignments in the biological contexts such as the lung, population modeling, and logistic growth. We are intersted in your feedback on these assessments in their draft stages. We also welcome any input about the course. What skills from calculus would help biology majors in their future academic endeavors?

This poster will present the draft assessments and provide space for feedback.

Iron (Fe) is abundant among trace elements in forest ecosystems and important in the development and function of soils. We constructed a biogeochemical budget for Fe to better understand the behavior of Fe and its role in the development of Spodosols (podsolization). Fluxes of reduced (ferrous, Fe(II)) and oxidized (ferric, Fe(III)) iron draining through the soil profile were calculated.

Responses of plants to grazing are better understood, and more predictable, than those of consumers in grassland ecosystems of the North American Great Plains. In 2003, we began a large-scale, replicated experiment to examine the effects of grazing on ground-dwelling beetles (Tenebrionidae), an important consumer community in shortgrass steppe of north-central Colorado, USA. We sought to determine whether modifications of the intensity and seasonality of livestock grazing alter the structure and diversity of beetle communities compared to traditional grazing regimes.

The north slope of the Brooks Range has been glaciated several times since the Late Tertiary, resulting in a landscape with glacial sediments of various ages (modern to ca. 2 million years old) in close proximity. We used space as a substitute for time to investigate how terrain age affects biological attributes of streams in the Toolik Lake region of Arctic Alaska. Similar studies have been limited to successional sequences of streams on terrains deglaciated for up to only 200 years. We extended this model to streams draining terrains that have been deglaciated for up to ca.

Climate change, residential development, and timber harvesting are likely to be the primary disturbance agents affecting the forests of Massachusetts in the coming decades. One source of uncertainty is the potential rise of a forest biomass energy industry and the ensuing increases in harvesting to meet demand for feedstock. Under Massachusetts’ Renewable Portfolio Standard, potential future demand for biomass electricity could be around 165 MW, which would require up to 2 million Mg of woody biomass annually.

Increased woody plant cover in grasslands is a global phenomenon and a critical threat to conservation of grasslands and their biodiversity. Changes in land management, such as reduced fire frequency, can increase woody plant abundance, while other factors such as increased CO₂ concentration, N deposition, and habitat fragmentation might be contributing factors.

Microbes are of critical importance but are a poorly understood component of arctic stream ecosystems. They are responsible for recycling organic matter and regenerating nutrients that are essential to the food webs of aquatic ecosystems. We tested the hypothesis that differences in highly contrasting parent lithologies (non-carbonate and ultramafic), stream habitat (sediments and rocks), and stream biogeochemistry influence the structure of bacterial biofilm communities in arctic streams.

Ecosystems worldwide are faced with climate change. In the northeastern United States, climate change is coupled with nitrogen deposition from air pollution. The objective of this study is to determine how soil warming and nitrogen deposition influence species richness, diversity, and abundance of vegetation in a northeastern forest. Our study site is the chronic Soil Warming and Nitrogen Fertilization experiment at the Harvard Forest Long Term Ecological Research site.