Contact Info:
Amanda Ash
Department of Geological Sciences
University of Michigan
425 East University
Ann Arbor, MI 48109-1063
phone: (734) 763-9368
fax: (734) 763-4690
email: asha@umich.edu

Date Prepared: November 2002

Objectives

Tree rings provide an important chemical archive that may record information about nutrient cycling and ecosystem function prior to the onset of acidification. However, some basic assumptions concerning the validity of using dendrochemical analyses to track environmental perturbations remain to be tested. This study will examine:
1. The variation in foliar, bole wood, branch, and root chemistry within an individual, including the extent to which Ca in sap exchanges with Ca in older growth increments. And, whether the changes in chemistry through time of different organs follow a similar trend.
2. Natural variation in chemistry within species and variation in chemistry among species growing on similar soils but having different physiological demands and constraints.
3. Whether or not Ca/Sr ratios are modified during uptake by trees using the W1 calcium addition experiment.

Approach

For each of these collections, we will measure elemental concentrations and strontium isotope ratios in all vegetation samples to investigate the sources of plant-available calcium through time and to evaluate the fidelity of the dendrochemical record.

Within- individual variation
Collections were made in the fall of 2002 by Tim Fahey, Ian Halm, and crew. In the calcium application area of W1, one individual each of yellow birch (Betula alleghaniensis), sugar maple (Acer saccharum), and American beech (Fagus grandifolia) were sampled. In Bear Brook, a control area, one individual each of Betula alleghaniensis, Fagus grandifolia, balsam fir (Abies balsamea), paper birch (Betula papyrifera), and red spruce (Picea rubens), and two individuals of Acer saccharum were sampled. Foliage, branches, five root orders, and 4-5 core samples of bole wood at 10-foot intervals (using a Swedish hammer) were collected for each individual. Analysis of samples from this collection will help elucidate, in a systematic manner, how much chemical variation there is among different organs within an individual.

Graduate Advisor, Dr. Joel Blum coring a sugar maple Photo by Steve Peters

Interspecific variation and Ca/Sr uptake
During the summer of 2002, individuals of Acer saccharum, Fagus grandifolia, Betula alleghaniensis, Picea rubens, and Abies balsamea, were sampled for foliage and for bole wood, using an 18 inch, 0.200" diameter increment borer. For conifers, both the current year's and previous years' needles were collected. Collections were made in each of the four elevation zones of W1 and in the control area to the west and north of W1. Evaluation of bolewood and foliar chemistry from each species will clarify sources of interspecific variation as they pertain to physiology and environment. Study of this collection will further clarify the variation in vegetational chemistry within species between wollastonite application and non-application areas to elucidate the extent to which the Ca/Sr ratios in plant tissue accurately reflect nutrient available sources of Ca/Sr.

Point Source study: Samples from Acer saccharum, Fagus grandifolia, Betula alleghaniensis, Picea rubens, Abies balsamea, Fraxinus Americana, Dryopteris intermedia, and Onoclea sensibilis all growing on one boulder were sampled for foliage, wood, and roots. Samples of moss, the thick leaf litter matt, and the granodioritic boulder were also taken. All plant tissues will be analyzed for elemental concentrations and strontium isotope ratios and compared with the chemical composition of the boulder and leaf litter on which they were growing. Patterns of interspecific variation and intraspecific variation within plant organs will be studied with respect to available nutrient sources.