Larry H. McCormick

Growth response of northern red-oak and yellow- poplar seedlings to light, soil moisture and nutrients in relation to ecological strategy

Abstract Northern red oak ( Quercus rubra L.) and yellow-poplar ( Liriodendron tulipifera L.) were grown from seed in containers for two seasons in six environments consisting of three levels of edaphic richness (high-moisture/high-fertility, high-moisture/low-fertility, low-moisture/high-fertility) and two light intensities (100%, 20% full sun). Seedling height, dry weights of leaves, stems, and roots, and projected leaf and root surface areas were measured at the end of the second growing season. Low levels of light, moisture, and fertility significantly reduced growth of both species, and effects of low moisture and low fertility were greater in full sun than in shade. Total dry-weight of yellow poplar was 36% greater than that of red oak under combined high levels of light, moisture, and nutrients, while total dry-weight of oak was 38–126% greater than that of poplar where at least one resource was at a suboptimal level. Reductions in growth for yellow-poplar due to low levels of all resources were greater than those for red oak, indicating greater stress tolerance for oak. Yellow-poplar had significantly greater shoot: root ratio and greater partitioning of leaf and root mass to absorbing surfaces compared to red oak. The relative tolerance of red oak to low resource levels and morphology suggests adaption to moderately unproductive environments (stress-tolerant strategy), while the characteristics of yellow-poplar (opportunistic capture of plentiful resources, maintenance of large absorbing surfaces) suggests adaptation to more productive environments (competitive strategy). The growth strategy of red oak is discussed in relation to ecological requirements for regeneration.

Soil pH, extractable aluminum and tree growth on acid minesoils

Abstract Paper birch and hybrid poplar were grown in acid minesoils amended with different rates and types of lime. Growth of the trees was correlated with soil pH, Ca, Mg, K, P and three measures of extractable Al ‐ 1 N KCl, 0.01 M CaCl2 and H2O extractable Al. Correlations between soil pH and extractable Al and between the three measures of extractable Al were also determined. Soil pH accounted for the largest share of the total variation in root and shoot growth of both species over all soils. Correlations between tree growth and extractable Al for all soils combined were low and generally non‐significant. Significant correlations were obtained between soil pH and extractable Al and between the three measures of extractable Al, however, the relationships varied among soils.

Variation in mineral content of red maple sap across an atmospheric deposition gradient

Xylem sap was collected from red maple (Acer rubrum L.) trees during the spring of 1988 and 1989 at seven forest sites along an atmospheric deposition gradient in north central Pennsylvania and analyzed for pH and twelve mineral constituents. The objectives of the study were to examine the sources and patterns of variation in red maple sap chemistry across an atmospheric deposition gradient and to assess the feasibility of using sap analysis as an indicator of nutrient bioavailability. For most sap constituents, there was considerable spatial and temporal variation in concentration. Sources of variation included within and between site variation, date, and year of collection. The nature and extent of variation varied for different constituents. Site differences were similar in 1988 and 1989 for most sap constituents and for some constituents corresponded with differences in soil levels.