Donald H. DeHayes

Acid Rain Impacts on Calcium Nutrition and Forest Health

Forest ecosystems throughout the world are exposed to acid rain, a complex solution consisting largely of H+, SO42-, NH4+, and NO3- pollutant ions derived from sulfur and nitrogen oxides. Although the public in the United States may view acid deposition as a localized pollution issue specific to certain regions of North America and northern Europe, recent evidence of acidic deposition throughout much of Asia, including tropical forest regions, has demonstrated that acid deposition is actually a global phenomenon (Abate 1995).

Forest Responses to Changing Climate: Lessons from the Past and Uncertainty for the Future

The earth’s climate has undergone dramatic and long-term changes through natural processes many millennia before humans influenced global climate. Considerable evidence indicates that increasing concentrations of carbon dioxide and other greenhouse gases in the earth’s atmosphere will lead to near-term warming, perhaps as much as 2 to 4°C in northeastern North America. Given that the distribution of vegetation on earth has varied with past climate change, it is reasonable to expect that future climate change will affect forest composition and distribution. For reasons both ecological and economic, it is desirable to understand and be able to predict the extent and nature of the changes that might be expected in northern forests in response to climate warming.

Physiological and Environmental Causes of Freezing Injury in Red Spruce

For many, concerns about the implications of “environmental change” conjure up scenarios of forest responses to global warming, enrichment of greenhouse gases, such as carbon dioxide and methane, and the northward migration of maladapted forests. From that perspective, the primary focus of this chapter, that is, causes of freezing injury to red spruce (Picea rubens Sarg.), may seem somewhat counterintuitive and inconsistent with the overall theme of the book. However, the dramatically increased incidence of freezing injury to northern montane red spruce forests over the past four decades is, in fact, largely a function of human-induced environmental change. “Environmental change” in the context of this chapter includes both changing climatic patterns and chemical changes in the atmospheric, forest canopy, and/or soil environment that may directly or indirectly result from atmospheric wet (precipitation or cloud water) or dry (direct deposition of gases or aerosols) deposition.

Relative quantification of membrane-associated calcium in red spruce mesophyll cells

Abstract We describe a method for localizing and comparing relative amounts of plasma membrane-associated calcium ions (mCa) in complex tissues and verify the procedure for mesophyll cells of red spruce (Picea rubens Sarg.) needles. This technique incorporates epifluorescence microscopy using the fluorescent probe chlorotetracycline (CTC) with computer image processing and analysis. Using an appropriate standardization for image brightness, the procedure allows relative quantitative comparison of CTC-fluorescence in the plasma membrane-cell wall region that corresponds to relative amounts of mCa. The technique effectively discerned mCa differences among red spruce needle sections exposed to treatments designed to alter mCa levels in vitro. Estimates of mCa for nine red spruce seedlings, were highly repeatable over a 6 week period in late summer. This repeatability verifies that the described methods produce reliable and reproducible estimates of foliar mCa in woody plant foliage. By incorporating image analysis, this technique allows for relative quantitative estimates of mCa specific to the physiologically-important and labile pool of Ca associated with the plasma membrane-wall complex. Such measurements have not previously been reported for woody plant tissues and thus may provide new insights into the relative roles and responsiveness of mCa vs total foliar Ca pools.

Management of exotic timber trees in temperate regions of eastern North America: an assessment.

Abstract Based on data in the forestry literature and experiences at Kellogg Forest in southwest lower Michigan and Jericho Research Forest in northwest Vermont, the potential of various exotic conifers and hardwoods as timber trees in temperate eastern North America is assessed. Site adaptability, preferred seed sources and pest problems of several promising exotics are discussed and growth comparisons between exotic and native timber trees are made. It is suggested that wood production on many sites could be improved by planting exotics such as Norway spruce, the larches, Scotch pine, and English oak. However, further comparison trials with natives and exotics are needed before wide-scale planting of exotics can be recommended.