Select a title from the list below to see an abstract of the article. For information about ordering reprints of complete articles, contact ISA at (217) 355-9411 or isa@isa-arbor.com.
The Influence of Calcium Supplementation
on the Freezing Tolerance of Woody Plants
by Glynn C. Percival, Celia Boyle, and Lynn Baird
Abstract. The effects of calcium (Ca2+) supplementation on the freezing resistance of white poplar (Populus alba, frost hardy) and hornbeam (Carpinus betulus, frost sensitive) were studied by monitoring alterations in leaf fatty acids, chlorophyll fluorescence emissions, necrosis, mortality, and growth. Calcium supplementation had no significant effect on leaf fatty acids before, and from weeks 2 through 8 after, freezing. Percentages of the saturated fatty acid C16 were significantly higher in Ca2+-supplemented plants immediately following freezing (day 1) only. In P. alba, leaf chlorophyll fluorescence and necrosis values were significantly higher and lower than in controls immediately after freezing; readings from weeks 2 through 8 did not significantly differ from controls. Leaf chlorophyll fluorescence and necrosis values in C. betulus after freezing were significantly higher and lower than in controls throughout the experiment. Calcium concentrations were significantly higher in supplemented plants. Lower mortality rates and root and leaf electrolyte leakage values, and higher root, shoot, and leaf dry weights and leaf area recorded in Ca2+-supplemented plants indicate that freezing tolerance may be increased by application of Ca2+ fertilizer.
The Assessment of Tree Priority
at the United States Military Academy
by Thomas L. Green and Robert C. Jones
Abstract. The United States Military Academy at West Point, New York, attracts more than three million visitors each year. Trees dominate the 1,700-ac (700-ha) urban community that is part of a 16,000-ac (6,500-ha) heavily forested scenic hillside on the west bank of the Hudson River. A tree inventory was conducted in 1996 and 1997 to help develop a tree management program. This inventory included typical inventory elements used to determine maintenance priority: pruning, removal, and hazard assessment as well as species, size, and condition. This inventory, however, adds an additional element usually not found in other tree inventories--overall priority assessment. Overall tree priority values were determined by assigning specific values to each tree according to species, condition, specimen, function, heritage, memorial, historical, location, and special designation (tree trail), then adding the values together for a total priority value. Priority values can help the landscape manager better identify the trees that have the most significance on the property and provide the documentation necessary for better allocation of funds to preserve and protect those trees considered the most important. This method of priority assessment can also be used with any tree inventory for college campuses, parks, golf courses, cemeteries, and municipalities.
Effect of Herbicide Maintenance
of an Electric Transmission Line Right-of-Way on Butterfly Populations
by W.C. Bramble, R.H. Yahner, and W.R. Byrnes
Abstract. A study was carried out in 1997 of the butterfly populations on the right-of-way of a 230-kV transmission line of GPU Energy in the Allegheny Mountain Physiographic Province of central Pennsylvania. The objective was to determine if herbicide spray maintenance had produced an adverse impact on butterfly populations. Butterfly counts were made at 7 points in time during the growing season to coincide with flowering of important plant species. On the handcut control unit, there was a total of 14 butterfly species and 58 individuals present over the growing season. In contrast to this, there was a total of 20 butterfly species present on the high-volume basal spray unit, 19 species on the mowing plus herbicide spray unit MH-1, and 22 species on the mowing plus herbicide spray unit MH-3. The number of individual butterflies ranged from 172 to 186 on the 2 mowing plus herbicide spray units to 342 on the high-volume basal spray unit. These results indicate that herbicide spray maintenance had not produced an adverse effect on butterfly species and number of individuals compared to handcutting without herbicides.
Detection of Wood Decay in Blue Gum
and Elm: An Evaluation of the Resistograph® and the Portable Drill
by Laurence R. Costello and Stephen L. Quarles
Abstract. Decay and soundwood assessments made with the Resistograph® and the portable drill were compared with laboratory measurements of wood density. Sixteen Tasmanian blue gum (Eucalyptus globulus) and 5 Scotch elm (Ulmus glabra) were evaluated in the field, cut, sectioned along Resistograph and drill test paths, and measured for density. Resistograph measurements of soundwood depth agreed closely with density measurements in 85.5% of all cases for blue gum and 100% of all cases for elm. Portable drill measurements agreed closely with density measurements in 73% of cases for blue gum and 81% for elm. Drill evaluations varied considerably among operators. For both species, the Resistograph provided a higher level of consistency and reliability than the portable drill. For either method, familiarity with wood resistance patterns of the test species is critical for an accurate interpretation of decay presence or absence.
Effects of 3 Trunk Support
Systems on Growth of Young Pyrus calleryana Trees
by Pavel Svihra, David Burger, and Deborah Ellis
Abstract. Trunk support of newly planted Pyrus calleryana saplings (from 57-L [15-gal] containers, 280 cm [9 ft] tall) for 2 years with 2 stakes was compared with the TreeSaver™ Tree Anchoring System (3 rubber support straps anchoring each tree) and with a prototype of Bio-Tie (single-stake system holding each tree in an upright position with a flexible cord allowing for multidirectional movement of each tree). During the first year after installation, the double-staked trees grew taller than those supported with Tree Saver or Bio-Tie systems (P < 0.05). After the trunk supports were removed and the trees were allowed to sway normally in the third year, the differences in growth increase disappeared. The Bio-Tie-supported tree trunks developed significantly more taper than either Tree Saver or the 2 stakes and remained more tapered after the stem supports were removed.
Evidence for the Downward Movement
of Materials Injected into Trees
by Terry A. Tattar and Stacy J. Tattar
Abstract. Movement of the xylem-mobile dyes (acid fuchsin, saffranin
O, and gentian violet) after lower trunk or root flare injection was found
to occur both upward into the xylem of stems, twigs, and leaves and downward
into the xylem of woody roots, at most times of year when soil temperatures
equaled or exceeded 5°C (40°F). Similar patterns of movement of
xylem-mobile dyes were observed on the following species tested: American
chestnut, black birch, eastern hemlock, eastern white pine, red maple,
red oak, weeping willow, white ash, and white birch. Downward movement
of dye into root systems involved all ages of xylem tissues present within
a root, while upward movement was confined to the most recently formed
xylem growth ring. Evidence is presented of initial downward dye movement
followed by later upward movement within a 12-hour period. Our results
suggest that xylem-mobile materials injected into trees may be distributed
into stem, leaf and root tissues under most growing conditions.