UVM Theses and Dissertations
Format:
Print
Author:
Halman, Joshua M.
Dept./Program:
Natural Resources
Year:
2013
Degree:
PhD
Abstract:
The northeastern United States has been subject to pollutant and acidic deposition for well over a half-century. These acidic inputs alter the soil nutrition of forests by lowering pH, increasing the mobility of phytotoxic aluminum (Al), and reducing essential base cation availability, most notably calcium (Ca), from ecosystems. Ca-depletion in the region has been associated with the impairment of tree health and the decline of multiple tree species, most notably red spruce (Picea rubens Sarg.). Although mechanistic connections between red spruce decline and Ca-depletion are well studied, the effects of Ca-depletion on other species in the region are less understood.
Many paper birch (Betula papyrifera Marsh.) crowns in the northeast were severely damaged by ice loading in January 1998. Crown condition, dieback and radial growth were assessed for mature trees throughout the Green Mountains, and associated soils were sampled for cation nutrition. All trees sampled were damaged by the ice storm, regardless of soil-Ca status. However, trees growing on soils with greater soilCa were able to rebound in radial growth following injury, while those trees growing in soils with low-Ca and high-AI levels continued to exhibit reduced radial growth. Because most sites were at higher altitudes, the contribution of elevation to changes in crown vigor and growth was assessed, but soil-Ca levels better explained observed patterns of vigor and growth.
In a long-term study at the Hubbard Brook Experimental Forest (HBEF; Thornton, NH), additions of Ca (to mimic pre-pollution conditions) and A1 (to mimic continued pollutant loading) were made beginning in 1995. In 2009, foliar nutrition and radial growth of sugar maple (Acer saccharum Marsh.) and American beech (Fagus grandifalia Ehrh.) were quantified to determine the differential impacts of treatments, arid to identify species-specific trends. Ca-treatment enabled sugar maples and American beech not in the overstory to rapidly increase growth following ice storm damage that opened canopies. Among American beech, however, A1-treatment resulted in the greatest increase in growth due to A1-associated increases in tree mortality in these plots. In the same plots, mature sugar maple physiology was evaluated. A1-treatment, and subsequent reductions in foliar Ca, resulted in greater cellular damage, impaired carbon (C) relations, reduced recovery from a defoliating event, and reduced reproductive success.
The research presented here provides further indications that regional Cadepletion has resulted in reductions to tree health for multiple species. Furthermore, this work identifies a variety of mechanisms by which Ca-depletion can hinder sugar maple physiology and dynamics with sympatric species, and introduces an additional species (paper birch) that is ill-equipped to deal with stress in the absence of adequate Ca-availability.
Many paper birch (Betula papyrifera Marsh.) crowns in the northeast were severely damaged by ice loading in January 1998. Crown condition, dieback and radial growth were assessed for mature trees throughout the Green Mountains, and associated soils were sampled for cation nutrition. All trees sampled were damaged by the ice storm, regardless of soil-Ca status. However, trees growing on soils with greater soilCa were able to rebound in radial growth following injury, while those trees growing in soils with low-Ca and high-AI levels continued to exhibit reduced radial growth. Because most sites were at higher altitudes, the contribution of elevation to changes in crown vigor and growth was assessed, but soil-Ca levels better explained observed patterns of vigor and growth.
In a long-term study at the Hubbard Brook Experimental Forest (HBEF; Thornton, NH), additions of Ca (to mimic pre-pollution conditions) and A1 (to mimic continued pollutant loading) were made beginning in 1995. In 2009, foliar nutrition and radial growth of sugar maple (Acer saccharum Marsh.) and American beech (Fagus grandifalia Ehrh.) were quantified to determine the differential impacts of treatments, arid to identify species-specific trends. Ca-treatment enabled sugar maples and American beech not in the overstory to rapidly increase growth following ice storm damage that opened canopies. Among American beech, however, A1-treatment resulted in the greatest increase in growth due to A1-associated increases in tree mortality in these plots. In the same plots, mature sugar maple physiology was evaluated. A1-treatment, and subsequent reductions in foliar Ca, resulted in greater cellular damage, impaired carbon (C) relations, reduced recovery from a defoliating event, and reduced reproductive success.
The research presented here provides further indications that regional Cadepletion has resulted in reductions to tree health for multiple species. Furthermore, this work identifies a variety of mechanisms by which Ca-depletion can hinder sugar maple physiology and dynamics with sympatric species, and introduces an additional species (paper birch) that is ill-equipped to deal with stress in the absence of adequate Ca-availability.