Community and population dynamics of spruce-fir forests on Whiteface Mountain, New York: recent trends, 1985-2000

We remeasured two sets of permanent plots in old-growth, spruce–fir forests on Whiteface Mountain to quantify ongoing vegetation dynamics at sites impacted by spruce decline. One set of plots was a stratified random sample of the vegetation in a subalpine watershed (Baldwin site). The other was selected to represent forest conditions in a high-elevation subset of the spruce–fir forest (Esther site). Between 1987 and 1997, there was a significant increase in aboveground tree biomass at Baldwin with the majority of the increment due to the growth of canopy-sized trees. This growth occurred with little change in either species composition or size structure. The annual mortality rate of 1.2%·year–1 for canopy-sized red spruce (Picea rubens Sarg.) in Baldwin almost matched the recruitment rate of 1.4 stems/ha per year. In addition, the relative growth rate of spruce was significantly faster than associated species. In contrast, spruce trees in Esther died at a rate of the 3.6%·year–1 (1985–1995), and survivors grew more slowly than other species. The most obvious community-level trend at Esther (1985–2000) was an increase in overall tree density with most of this increase due to ingrowth of small trees. The demography of the spruce population at Baldwin suggests that the decline is over for at least this population

In Situ Decomposition of Northern Hardwood Tree Boles: Decay Rates and Nutrient Dynamics in Wood and Bark

The decomposition of coarse woody debris contributes to forest nutrient sustainability and carbon balances, yet few field studies have been undertaken to investigate these relationships in northern hardwood forests. We used a paired-sample approach to study the decomposition of sugar maple (Acer saccharum Marsh.), American beech (Fagus grandifolia Erhr.), and yellow birch (Betula alleghaniensis Britt.) boles at the Hubbard Brook Experimental Forest in New Hampshire. Mass loss over 16 yr followed a first-order exponential decay pattern with half-lives ranging from 4.9 to 9.4 yr in bark, and 7.3 to 10.9 yr in wood. Nitrogen and phosphorus concentrations increased significantly during decomposition, resulting in sharp decreases in C:N and C:P ratios. We did not, however, observe significant net increases in the amount of N or P stored in decomposing boles, as reported in some other studies. Calcium concentration decreased by up to 50% in bark, but more than doubled in wood of all species. The retention of Ca in decomposing wood helps maintain Ca pools in this base-poor ecosystem. Together, the exponential model for mass loss and a combined power-exponential model for changes in nutrient concentrations were able to simulate nutrient dynamics in decomposing boles after clear-cutting in an adjacent watershed

Chemical Changes in Soil and Soil Solution after Calcium Silicate Addition to a Northern Hardwood Forest

Liming has been used to mitigate effects of acidic deposition in forest ecosystems. This study was designed to examine the effects of calcium (Ca) supply on the spatial patterns and the relations between soil and soil solution chemistry in a base-poor forest watershed. Watershed 1 at the Hubbard Brook Experimental Forest in New Hampshire, USA was experimentally treated with wollastonite (CaSiO3) in October, 1999. Exchangeable Ca (Ex-Ca), soil pHs (in 0.01 M CaCl2), effective cation exchange capacity (CECe), and effective base saturation (BSe) increased, while exchangeable acidity (Ex-Acid) decreased in organic soil horizons in 2000 and 2002. Mineral soils experienced either small increases in Ex-Ca, pHs, CECe, BSe, small decreases in Ex-Acid or no changes. Thus, most of the added Ca remained in the forest floor during the study period. Prior to the treatment the BSe decreased with increasing elevation in organic and mineral soil horizons. This spatial pattern changed significantly in the forest floor after the treatment, suggesting that soils at higher elevations were more responsive to the chemical addition than at lower elevations. Soil solutions draining the forest floor responded to the treatment by increases in concentrations of Ca, dissolved silica, pH, and acid neutralizing capacity (ANC), and a decrease in inorganic monomeric Al (Ali). Treatment effects diminished with increasing soil depth and decreasing elevation. Positive correlations between Ca/total monomeric Al (Alm) in soil solution and Ex-Ca/Ex-Al ratios in soil indicated that changes in the chemistry of soils significantly influenced the chemistry of soil water, and that Ca derived from the dissolution of wollastonite mitigated the mobilization of Al within the experimental watershed

Biotic Control of Calcium Cycling in Northern Hardwood Forests: Acid Rain and Aging Forests

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42435/1/30060399.pd

Long-term Trends from Ecosystem Research at the Hubbard Brook Experimental Forest

The Hubbard Brook Experimental Forest was established by the U.S. Forest Service in 1955 as a major center for hydrologic research in the Northeast. The Hubbard Brook Ecosystem Study originated 8 years later with the idea of using the small watershed approach to study element flux and cycling and the response of forest ecosystems to disturbance. Since that time, the research program at Hubbard Brook has expanded to include various physical, chemical and biological measurements collected by researchers from a number of cooperating institutions. Collaborative, long-term data are the keystone of the Hubbard Brook Ecosystem Study and have provided invaluable insight into how ecosystems respond to disturbances such as air pollution, climate change, forest disturbance, and forest management practices. This report highlights long- term ecological trends at Hubbard Brook, provides explanations for some of the trends, and lists references from the scientific literature for further reading

Influence of landscape position and vegetation on long-term weathering rates at the Hubbard Brook Experimental Forest, New Hampshire, USA

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155853/1/Nezat_et_al_2004_Influence_of_landscape.pd

The relative uptake of Ca and Sr into tree foliage using a whole-watershed calcium addition

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155859/1/Dasch_et_al_2006_Relative_uptake.pd

New insight into calcium depletion in northeastern forests

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155857/1/Yanai_et_al_2005_New_insights.pd