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The longevity of a single 22.4 Mg·ha−1 application of dolomitic limestone at four northern hardwood stands was evaluated over 30 years (1986–2016) to determine whether changes in soils, foliage, and tree growth were sustained on the unglaciated Allegheny Plateau in northern Pennsylvania, USA. In limed plots, soils, sampled to 45–55 cm depth, and sugar maple (Acer saccharum Marsh.) and black cherry (Prunus serotina Ehrh.) foliage had significantly (P ≤ 0.05) greater concentrations of calcium (Ca) and magnesium (Mg) through 2016 compared with samples from unlimed plots. Ca and Mg capitals (g·m−2) in the Oi through A horizons combined were greater on limed plots than unlimed plots, largely due to increases in the thickness and nutrient concentration in the A horizon. Over 30 years, sugar maple basal area increment (cm2·year−1 BAINC) was greater in limed plots (30.6 cm2·year−1 vs unlimed 13.3), American beech (Fagus grandifolia Ehrh.) BAINC was unaffected by lime application, and black cherry BAINC was reduced in limed plots compared with unlimed plots. The sustained effect of this one-time lime treatment shows the strong role of efficient nutrient cycling in forests and suggests that the benefits over a substantial portion of a stand rotation may increase the feasibility of operational liming. [ABSTRACT FROM AUTHOR]

Sugar maple (Acer saccharum Marsh.) decline disease, decreased growth, and regeneration failure have been related to a low supply of Ca and Mg. There is increased interest in augmenting cation availability via liming, but there is little information on the amounts of lime required and the longevity of the lime treatment. A single application of 22.4 Mg ha-1 of dolomitic limestone in 1985 at four forested sites in Potter County, PA has shown that soil, soil water, and sugar maple foliage chemistry are significantly altered by liming and the changes in soils and foliage persist as long as 21-yr post-treatment. By 2001, only 3 kg ha-1 of lime remained undissolved while increases in exchangeable Ca and Mg, and pH continued through 2006 at depths up to 35 to 45 cm. Exchangeable Mn and Al concentrations were significantly reduced by lime application, though effects were slower to develop at deeper depths. Soil solution chemistry from 1996 was highly variable but reflected the changed soil nutrients. On limed plots, sugar maple foliage had elevated concentrations of Ca and Mg in 2006 samples, indicating the persistence of the lime treatment. Comparison of Ca/Al ratios in soil solution, soils, and foliage show inconsistencies from previous published risk thresholds. Species-specific thresholds of Ca and Mg availability in soil and foliage have better potential management application and should be more rigorously tested as stress indicators. [ABSTRACT FROM AUTHOR]

Anomalous dark growth rings have been observed in black cherry (Prunus serotina) sawlogs from northwestern Pennsylvania making the logs unsuitable for veneer products. Thirty-six cross sections with dark rings, each traceable to one of ten stands, were obtained from a local mill and sections were dated and annual ring widths were measured. One or more dark rings were found in 30 of the 36 cross sections. The most frequent years in which dark rings formed were 1994, on 55% of cross sections, and 1995, on 72% of cross sections. Both years were coincident with widespread cherry scallop shell moth (Hydria prunivorata) outbreaks. GIS layers and maps obtained from the Allegheny National Forest were used to document cherry scallop shell moth defoliations in these stands. These rings show a darkened discoloration through all or portions of the annual ring without characteristics typical of gum spots or gum defects caused by traumatic injury from bark beetles or cambium miners. Microscopic examination of the rings revealed darkened fiber cell walls, but no other cellular abnormalities. Dark rings are more common in stands with a high proportion of the total basal area composed of black cherry. These stands also are more susceptible to repeated defoliations from cherry scallop shell moth. [ABSTRACT FROM AUTHOR]

In Pennsylvania, two hypotheses compete to explain the chronic oak ( spp.) regeneration problem: excessive deer browsing and soil cation depletion. We tested these hypotheses by evaluating the effect of forest liming and deer exclosure fencing on northern red oak ( L.) seedling growth and nutrition in five oak shelterwood stands in Pennsylvania over 6 years. In each stand, four planting plots were located inside a 2.4 m high woven wire fence and another four were established outside the fence. About 225 northern red oak acorns were planted in each plot in spring 2004. Dolomitic limestone was applied to randomly selected plots at rates of 0, 4.5, 9.0, and 13.5 Mg·ha-1 during May 2004. There were no statistically significant ( P ? 0.05) growth responses to lime applications. The only significant growth responses resulted from the fence versus no-fence treatment. A significant ( P < 0.003) fence × year interaction for seedling height and root collar diameter indicates differential impacts of deer browsing. By 2009, seedlings inside fences averaged 32 cm tall, while seedlings outside the fences averaged 17 cm. Similarly, root collar diameter averaged 6.6 mm outside the fences and 9.1 mm inside fences. [ABSTRACT FROM AUTHOR]

Sugar maple ( Acer saccharum Marsh.) is a keystone species in the northern hardwood forest, and decline episodes have negatively affected the growth and health of sugar maple in portions of its range over the past 50+ years. Crown health, growth, survival, and flower and seed production of sugar maple were negatively affected by a widespread decline event in the mid-1980s on the unglaciated Allegheny Plateau in northern Pennsylvania. A long-term liming study was initiated in 1985 to evaluate responses to a one-time application of 22.4 Mg·ha-1 of dolomitic limestone in four northern hardwood stands. Over the 23-year period ending in 2008, sugar maple basal area increment (BAINC) increased significantly ( P ≤ 0.05) in limed plots from 1995 through 2008, whereas American beech ( Fagus grandifolia Ehrh.) BAINC was unaffected. For black cherry ( Prunus serotina Ehrh.), the third principal overstory species, BAINC and survival were reduced in limed plots compared with unlimed plots. Foliar Ca and Mg remained significantly higher in sugar maple foliage sampled 21 years after lime application, showing persistence of the lime effect. These results show long-term species-specific responses to lime application. [ABSTRACT FROM AUTHOR]

Determines the effects of lime fertilization on sugar maple in Pennsylvania. Responses of tree vitality to lime additions; Changes in foliar and soil elements; Correlation between tree growth and crown vitality.

The overall objective of this field study was to determine if Pinus nigra (Austrian Pine) could serve as a useful biomonitor to evaluate multi-year concentrations of total mercury (tHg) in vegetation within southwestern Pennsylvania. Austrian Pine has been widely planted as an ornamental, and formerly as a Christmas tree, and is now naturalized within the region. We collected needle samples annually during October 2004-2010 at 15-21 locations within a 5000-km² study area. Because Austrian Pine trees typically retain needles for 3 years, we collected samples from 3 needle-age groups: current year (~0.5 y old in October), previous year (~1.5 y old), and third-year (-2.5 y old), and analyzed them for total mercury (tHg). Across all years and plots, mean tHg concentrations among the 3 needle ages were significantly (P < 0.05) different from each other. Mean tHg concentration was greatest in the 2.5-yr-old needles (25.9 ± 3.4 ng/g), less in 1.5-yr-old needles (20.2 ± 3.2 ng/g), and least in the 0.5-yr-old needles (11.3 ± 2.3 ng/g). The greatest mean tHg content in the oldest needles indicates that Austrian Pine may sequester atmospheric Hg in/on its needles. Although the tHg concentrations within all 3 needle ages declined slightly during 2004-2010, downward linear trends were not significant, possibly due to the short sampling period (7 years). Needle tHg concentrations were significantly less in the northeastern portion of the study area, located farthest downwind from industrial sources of tHg, and may represent background tHg levels for conifers in the region. Results from this study suggest that any biomonitoring program involving conifers should consider needle age when developing sampling protocols. In addition, results suggest that abscised older pine needles may contribute substantially to the tHg soil burden beneath conifer stands. This is the first report from North America regarding tHg concentrations in/on various-aged Austrian Pine needles. Austrian Pine may prove useful as a biomonitor when evaluating spatiotemporal patterns of tHg accumulation within vegetation in eastern North America. [ABSTRACT FROM AUTHOR]