Treesearch

Cation loss from forest soils may be a contributing factor in some cases of sugar maple decline. We undertook three studies examining changes in base cations in forest floors.

Substantial amounts of calcium have been depleted from the soils of northern hardwood forests in northern New Engtand over the past 50 years. Portions of this depleted calcium have been incorporated into the biomass of the aggrading forests; however, significant amounts have been leached into drainage waters and lost from the ecosystem.

Evidence is accumulating that decline of sugar maple, Acer saccharum Marsh., in northern Pennsylvania may be related to overall site fertility as reflected in the chemistry of soil water and bolewood xylem. In this paper we discuss factors related to varying site fertility, including effects of soil liming, past glacialion, topographic position and soil acidification.

Some recent literature suggests that thinning should not be conducted immediately prior to, during, or immediately following an outbreak of defoliating insects. Although the individual effects of both defoliation and thinning are well documented in the literature, no study has assessed the combined effect of these two stressors. An outbreak of forest tent caterpillar, Malacosoma disstria Hbn., in the Tug Hill region of New York from 1990 to 1993 afforded the opportunity to assess the combined effects using a 2x2 factorial design.

Forest tent caterpillar (FTC) feeds on several species of deciduous trees (Stehr and Cook 1968), in northeastern North America, quaking aspen is the preferred host of this spring-feeding insect. FTC commonly defoliates several thousands of hectares of aspen stands each year in Quebec (Bordeleau 1990), although its secondary hosts seldom are attacked.

Sugar maple-dominated forest ecosystems in the northeastern U.S. have been receiving precipitation nitrogen (N) inputs of 15 -20 kg N ha1 year1 since at least the mid 1980s sustained chronic N inputs of this magnitude into nutrient-poor forest ecosystems may cause eutrophication and affect ecosystem functioning as well as the nutritional balance of mineral elements in the tree crown.

Forest decline in eastern Canada was particuiarly severe in the early 1980's and is still prevalent in some areas (Bowers and Hopkin 1997). Early public and scientific opinions on the causes of forest decline were often not based on sound scientific knowledge. Factors such as acidic precipitation and ozone were rnost often mentioned as direct causes of forest decline in the early stages. Although standards of nutrition for sugar maple (Acer saccharum Marsh.) were not known at the time, some common nutrient deficiencies were identified: K in the Eastern Townships, Mg on some sandy soils,...

Growth of sugar maple (Acer saccharum Marsh.) in 7 northern Vermont stands managed for sap production and 22 unmanaged stands distributed around the state was studied for the period 1953-1992 in relation to stand nutrition and other site factors.

Accuracy of traditional foiiar analysis of nutrient disorders in sugar maple (Acer saccharum Marsh) is limited by lack of validation and confounding by nutrient interactions. Vector nutrient diagnosis is relatively free of these problems. The technique is demonstrated retrospectively on four case studies. Diagnostic interpretations consistently suggest that decline incidence involves Ca and Mg deficiency induced by toxic accumulation of Mn.