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Projects available for independent study (e.g., FOR498, or honor's thesis, ESF499)

The following opportunities for undergraduate student research related to Multiple Element Limitation in Northern Hardwood Ecosystems ( are currently available in Ruth Yanai’s lab.  Contact Heather Engelman ( for additional information.

1.  We are measuring the response of forests to nutrient limitation, by adding nitrogen, phosphorus, and calcium to 13 northern hardwood stands across northern New Hampshire.   We collected leaves from trees of five species; these require ashing, digesting, and chemical analysis.  Has nitrogen pollution caused forests to become N-saturated and P-limited?  Kara.

2.  We collected quantitative samples of leaf litter arthropods from all 13 of our sites.  Sorting these arthropods to order (or possibly to family) would help to answer a number of questions about the effect of nutrient additions (N, P, Ca) on the brown food web.  Theo

3.  Roots of yellow birch (ectomycorrhizal) and red maple (arbuscular mycorrhizal) were used to compare nutrient uptake in N & P treatment plots.  Since ectomycorrhizae are thought to be involved in N uptake, we expect them to be reduced in plots where N is added.  Likewise, since  arbuscular mycorrhizae are thought to be involved in P uptake, we expect them to be reduced in plots where P is added.

a. The ectomycorrhizal species associated with yellow birch roots will be characterized using DNA extractions and PCR.

b.  The arbuscular mycorrhizae associated with red maple roots will be analyzed for colonization by clearing, staining, and scoring AM features under a compound microscope.

4.  American beech seedlings of varying age classes were collected in N, P, and Ca treatment plots. Ectomycorrhizae species diversity and abundance will be quantified across nutrient treatment plots using DNA extractions and PCR. We expect to see differences in ectomycorrhizal species composition and abundance across treatment plots due to varying functional roles of EM fungi in uptake of N, P, and Ca.

For research apprenticeships (EFB 298), we can offer a variety of activities in the lab, including sorting roots from soil samples for the MELNHE project, weighing leaf litter, and entering and managing data.

Projects that have been put aside, but could be resumed:

Title: Phosphorus concentrations in forest streams in response to flow and harvesting


Type of work: laboratory, data analysis, and manuscript writing


Qualifications: experience with technical writing, SAS, and Excel


Background:Concentrations of P in streams draining forested catchments are so low (ppb) as to be below the detection limit of analytical techniques used for monitoring P in agricultural settings (ppm).  Patterns of P concentration and discharge from streams in forests are therefore poorly known, although P is a limiting nutrient to aquatic organisms.


Project Description: We have a large collection of stream water samples from the Catskill Mountains of NY State and access to similar samples from the White Mountains of New Hampshire.  These samples allow questions to be posed concerning the relation of P concentration to discharge (based on samples collected during storm events) and the effects of forest harvest (comparisons of clearcutting, partial cutting, or no cutting). The project would be based in the Soil Fertility Laboratory at SUNY-ESF.  The first challenge will be to get the method running again; it used to work for us, but the last person who tried it could not get a good standards curve.  Visiting other labs in Syracuse that successfully measure P at  ppb concentrations might be an important step.


Title:  The Extent and Cause of Regeneration Failure of Sugar Maple

Type of work: laboratory, data analysis, and manuscript writing


Qualifications: experience with technical writing, SAS, and Excel


Background:  Sugar maple is the most abundant species in the northern hardwood forest, the most widespread forest type in the Northern Forest. Where sugar maple has failed to regenerate in recent years (Jenkins 1997, Beaudet et al. 1999, Didier and Porter 2003), causes have not been fully ascertained. Factors commonly suggested include competition from interfering plants (Hane 2003), herbivory (Didier and Porter 2003, Gardescu 2003), and soil calcium depletion due to acid rain (Jenkins 1997). These causes must yet be evaluated in conjunction with natural factors such as the availability of a seed source and degree of overstory shading.


Project Description:   We will assess the current status of sugar maple regeneration across the region, and compare present conditions to those recorded in the past through the USFS Forest Inventory and Analysis (FIA), the North American Maple Project (NAMP), and surveys by the Wilderness Conservation Society (WCS). We will evaluate the importance of factors such as stand age, canopy density, interfering plants (e.g., beech and ferns), deer browsing, landscape position, and soil conditions  (e.g., drainage class, acidity, and calcium availability) for explaining spatial patterns in the distribution of sugar maple regeneration.  Additionally, we will evaluate the use of sugar maple regeneration as a bio-indicator of soil acidification and associated loss of biodiversity. 



Title: Comparison of Nutrient Uptake Models (FORTRAN programming) 


Type of work: FORTRAN programming


Qualifications: Experience with FORTRAN, modeling


Background: This project compares two approaches to modeling nutrient uptake at the root surface: a steady-state approach (Nye and Tinker, Yanai, Smethurst and Comerford), which fails to represent initial conditions, and a time-dependent approach (Barber, Cushman), which makes assumptions about initial conditions and doesn't allow time-varying input.  A third model simulates uptake using a finite-difference approach, rather than an analytical solution. 


Project Description:       

The problem is that the time step of the finite difference model must be very small when the rate of solute flux is large relative to the compartment size.  To run the entire model at this time step would be prohibitively slow.  The next task, therefore, is to embed the model in a shell that would optimize the time step for each soil compartment as the model runs.  Three sets of model parameters have been developed, representing Mg, K, and P uptake by red spruce seedlings.  The analytical models have already been run.  The comparison of models should be publishable if only the programming problem of optimizing the time step can be solved.   The model thus far.


Relevant Papers:


Yanai, R.D. 1994.  A steady-state model of nutrient uptake improved to account for newly-grown roots.  Soil. Sci. Soc. Am. J. 58: 1562-1571.


William, M., and R. Yanai.  1996.  Multi-dimensional sensitivity analysis and ecological implications of a nutrient uptake model.  Plant and Soil 180: 311-324.


Yanai, R.D., H. Majdi, and B.B. Park. 2003.  Measured and modeled nutrient concentrations in

bulk and rhizosphere soil in a Norway spruce stand.  Plant Soil 257: 133-142.


Title: Trace Metal Cycling 

Type of work: data analysis

Qualifications: open to anyone

Background: We have data on trace metals in various components of northern hardwood forest ecosystems.  These data are generated when samples of plant tissues or soils are analyzed for other purposes, and they represent an untapped source of information about elements that are not much studied.  Zinc is a micronutrient that is required in trace amounts by plants, but some species (notably birch species) have high concentrations of Zn, for unknown reasons.  We have leaf litter concentrations by species in 13 stands of different ages, along with forest floor concentrations; for 6 of these stands, we will also have soils data.  Similarly, manganese is an element that is little studied, though it has been implicated in sugar maple decline.


Other Projects: Please feel free to develop a research topic that would fit your interests and relate to or expand upon our current research.

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