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Multiple Element Limitation in Northern Hardwood
responsible for this project seek to clarify relationships between stand
age and the cycling of Calcium between biotic and abiotic pools in the
northern hardwood forest. The work involves a chronosequence of thirteen
stands for extensive research located throughout the
Mountain National Forest, six of which are at
Experimental Forest in Bartlett, NH, and one of which is at
Brook Experimental Forest in Woodstock, NH. More intensive research
will be conducted in nine stands at the Bartlett Experimental Forest.
Our overall objectives
are to describe differences in Ca cycling with stand age, and to determine
the source of Ca mobilized from mineral soil in young stands. We will
test our hypotheses using two experimental approaches: an extensive
one involving 13 stands that we have previously studied, and an intensive
one using replicate stands of three ages at a single site.
There is growing
concern that base cations are being depleted from forest soils in the
northeastern United States as a result of acid rain (Baes and McLaughlin
1984, Shortle and Bondietti 1992, Likens et al. 1998). These losses
from soil are likely to be compounded by timber harvesting and the associated
loss of nutrients, with Ca the element most likely to become limiting
(Federer et al. 1989). Recent studies have reported dramatic declines
in pools of exchangeable base cations (Johnson et al. 1994, Knoepp and
Swank 1994, Huntington et al. 2000). The loss of cations in general
and Ca in particular over past decades is thought to have adversely
affected forest productivity and health in eastern North America (Baes
and McLaughlin 1984, Shortle and Bondietti 1992) and Europe (Ulrich
et al. 1980, Graveland et al. 1994).
such as acid rain may not be the only factors influencing changes in
soil Ca over time. We suggest that forest age needs to be considered
when interpreting Ca cycling patterns. Our Ca budgets indicate that
young northern hardwood stands (<30 yrs old) transfer Ca from mineral
soil into aboveground vegetation, forest floor, and drainage water,
whereas older stands are in approximate steady state. This suggests
that young stands tap a pool of soil Ca that is not as available to
older stands. Identification of this pool is essential to predicting
the consequences of acid rain and forest management on ecosystem productivity.
Our proposed research will explore the effect of forest age on Ca cycling
in the northern hardwood forest. Our objectives are to describe differences
in Ca cycling in stands of different ages, and to determine the sources
of Ca mobilized from mineral soil as a function of stand age.
The proposed study
addresses the question of Ca depletion in northeastern forests, which
is critically important for both policy formulation and forest management.
At the nearby Hubbard Brook Experimental Forest, exchangeable Ca in
soil is predicted to be depleted in less than one harvest cycle, which
means that either the productivity of re-growing forests will very soon
be limited by Ca availability (Likens et al. 1998), or forests obtain
Ca from previously unrecognized pools. The proposed experiment will
improve our ability to predict the long-term implications of acid precipitation
in the context of forest succession.
traditionally put biology in a black box, minimizing the importance
of biotic processes to geochemistry, while ecologists have put weathering
in a black box, often ascribing to it whatever flux was necessary to
balance a budget. The lack of a dialectic between weathering and biotic
processes has limited our understanding of how nutrient cycling relates
to ecosystem productivity and environmental stress.
In this proposal,
we will make measurements that will allow us to define the importance
of biotic processes on altering weathering and Ca availability. Understanding
the importance of this interaction is key to defining sustainable forest
management practices. We need to know how intensively we can manage
northern hardwood forests before nutrient depletion limits forest productivity.
The proposed research will contribute to identifying sustainable forestry
practices in the northern hardwood forests of the northeastern United
non-silicate mineral sources of Ca (apatite and calcite) to northeastern
forest soils is important in calculations of Ca depletion because these
Ca sources do not contain Na, which is often used to estimate the rate
of Ca release by weathering. For example, Likens et al. (1998) calculated
Ca weathering release based on stream sodium fluxes and an assumed Ca/Na
weathering release ratio of 0.24 to 0.33. If non-sodium-bearing minerals
contribute significant amounts of Ca to the soil, as we suggest, then
rates of plant available Ca depletion could be significantly overestimated.
In addition to the
intellectual impacts of the study, this project will provide long-term
infrastructure for studies of succession and forest age in the northern
hardwood forest. Previous advances in our understanding of long-term
changes in ecosystem structure and function have relied heavily on chronosequence
studies. Such studies are subject not only to random sources of error
but also systematic ones: changes in technology and markets for wood
products have altered the nature of harvest treatments over time (Arthur
and Yanai 2000, Yanai et al. 2000). The proximity and similarity of
our experimental study area to the Hubbard Brook Experimental Forest
will magnify its utility to a broad spectrum of researchers.
This text was adapted from NSF Grant
Proposal # DEB 0235650, "Biotic Control of Calcium Supply: Distinguishing Sources to Regrowing Forests." Yanai, Hamburg, Arthur, Blum, 2003.
Blum, J., A.A. Dasch, S.P. Hamburg, R.D.Yanai, and M.A. Arthur. 2008. Use of foliar
Ca/Sr discrimination and 87Sr/86Sr ratios to determine soil Ca sources to sugar
maple foliage in a northern hardwood forest. Biogeochemistry
Yanai, R.D., J.D. Blum, S.P. Hamburg, M.A. Arthur, C.A. Nezat, T.G.
Siccama. 2005. New insights into calcium depletion in northeastern
forests. Journal of Forestry. 103: 14-20.
R.P. Phillips, M.A. Arthur, T.G. Siccama, and E. Hane. 2005. Spatial and temporal variation in
calcium and aluminum in northern hardwood forest floors. Water, Air,
and Soil Pollution. 160: 109-118.
S,P., R.D. Yanai,
M.A. Arthur, J.D. Blum and T.G. Siccama. 2003. Biotic
control of calcium cycling in northern hardwood forests: acid rain and
aging forests. Ecosystems 6: 399-404.
further information, feel free to contact any of the following people involved in the project:
Principal Investigators and Collaborators:
University of Kentucky
University of Michigan
Miami University of Ohio
Rochester Institute of Technology
University of New Hampshire
SUNY College of Environmental Science and Forestry