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 Compaction
and Soil Strength on the Establishment of Four Australian Landscape Trees
Karen D. Smith, Peter B. May, and Gregory M. Moore
Abstract. Two experiments were conducted to test the hypothesis that trees able to establish in urban soils will have a higher-than-average tolerance to the higher mechanical impedance and soil strength of compacted soils. Experiment 1 tested the ability of the roots of Corymbia maculata (spotted gum, syn. Eucalyptus maculata), Lophostemon confertus (brush box), Corymbia ficifolia (red flowering gum, syn. Eucalyptus ficifolia), and Agonis flexuosa (willow myrtle) seedlings to penetrate a sandy loam soil compacted to bulk densities of 1.4 and 1.8 mg m?3 at 13% gravimetric moisture content. While roots of all species were able to penetrate the soil at the higher bulk density, total root penetration depth was reduced by 60% in all four species. Experiment 2 tested the ability of Corymbia maculata and C. ficifolia to penetrate soil compacted at bulk densities 1.4, 1.6, and 1.8 mg m?3 at two moisture levels, 7% and 10% gravimetric moisture. At 7% moisture, both species were able to penetrate soil compacted to 1.4 and 1.6 mg m?3, but neither species was able to successfully penetrate soil compacted to 1.8 mg m?3. At 10% moisture, both species were able to penetrate soil compacted to 1.4 and 1.6 mg m?3. They also were able to successfully penetrate soil compacted to 1.8 mg m?3, although with significantly less depth of penetration than at the two lower bulk densities.
Tree Moisture Stress and Insect
Damage in Urban Areas in Relation to Heat Island Effects
Bert M. Cregg and Mary Ellen Dix
Abstract. We monitored crown air temperature, volumetric soil
moisture, leaf water potential, rates of gas exchange, and insect pests
of green ash (Fraxinus pennsylvanica ‘Marshall’s Seedless’), Austrian
pine (Pinus nigra Arnold), and northern red oak (Quercus rubra
L.) trees during a relatively hot summer in Lincoln, Nebraska, U.S. Air
temperatures and vapor pressure deficits (VPD) were much higher in trees
growing downtown than in nearby trees growing on the University of Nebraska
campus. Increased VPDs and reduced soil moisture decreased pre-dawn water
potential and gas exchange of ash and oak trees on the downtown site compared
to trees on campus. Green ash trees downtown had more damage from lilac
borers (Podosesia syringae (Harris) (Sesiidae)) than did trees on
campus. Aphids (Aphidiae) and lace bugs (Tingidae Corythucha arcuata (Say))
appeared to be more numerous on oak trees growing downtown than on those
growing on campus. Cultural treatments that improve soil moisture availability,
such as irrigating, increasing planter size, and mulching, are especially
critical on heat island sites and may reduce tree stress, pest damage,
and mortality.
Differential Feeding by
Adult Japanese Beetles on Foliage of Birch (Betula) Species and
Hybrids
Frank S. Santamour, Jr.
Abstract. Assessment of the relative resistance of various birches
to foliar feeding by adult Japanese beetles was complicated by the insects’
marked preference for leaves on spur shoots, as opposed to long-shoot leaves,
on many trees. Based on the limited numbers of trees tested, the susceptible
(most preferred) taxa were Betula alleghaniensis, B. davurica, B. nigra,
B. nigra ‘Heritage’, B. papyrifera, B. populifolia, B. pubescens,
B. uber, and B. utilis var. jacquemontii, although some
resistant individuals of B. papyrifera and B. populifolia
were found. Resistant taxa included B. lenta, B. maximowicziana, B.
pendula, and B. platyphylla var. japonica. There was
some indication that the factors influencing beetle feeding preferences
were inherited.
Effect of Vegetation Maintenance
of an Electric Transmission Right-of-Way on Reptile and Amphibian Populations
Richard H. Yahner, William C. Bramble, and W. Richard Byrnes
Abstract. A 2-year study of reptile and amphibian populations was conducted on a 230-kV transmission line right-of-way (ROW) of GPU Energy in the Allegheny Mountain Physiographic Province, Centre County, Pennsylvania, U.S., from June through October 1998 and March through October 1999. The objective was to compare the diversity and relative abundance of reptiles and amphibians between the ROW versus the adjacent forest, among five treatment units on the ROW, and between wire and borders zones on treatments on the ROW. Nine species were recorded during the study, with the three most common species being redback salamanders (Plethodon cinereus), northern redbelly snakes (Storeria occipitomaculata occipitomaculata), and northern ringneck snakes (Diadophis punctatus edwardsii). All nine species occurred on the ROW, but only redback salamanders and Jefferson salamanders (Ambystoma jeffersonianum) were found in the adjacent forest. The diversity and relative abundance ranged from six species in the stem-foliage unit to three species in the handcutting unit. Eight and six species, respectively, were noted in the wire and border zones of the ROW. However, 81% of the observations in wire zones were those of snakes, whereas 85% of the observations in border zones were salamanders. The ROW contained a much more diverse community of reptiles and amphibians than the adjacent forest. Forest-management practices can have negative impacts on populations of amphibians and reptiles. Thus, this study provides important information on forest-management practices required for the conservation of reptiles and amphibians.
Effect of Nursery Production
Method, Irrigation, and Inoculation with Mycorrhizae-Forming Fungi on Establishment
of Quercus virginiana
Edward F. Gilman
Abstract. Live oak (Quercus virginiana) trees were grown to about a 2.5 in. (6 cm) caliper in various container and field production systems, then transplanted to a landscape with and without mycorrhizae-forming spores under two irrigation regimes. Trees grew at nearly the same rate in the nurseries, regardless of production method. However, root distribution was altered. Low-profile, air root-pruning containers had less roots on the outside surface of the root ball than did traditional plastic containers. Application of mycorrhizae-forming fungi to the backfill soil at planting in a landscape had no impact on live oak the first 30 months after planting. However, nursery production method and irrigation frequency following planting had a huge influence on tree survival. Irrigating 2.5 in. (6 cm) caliper live oak for only 6 weeks after planting in spring in a slightly drier than normal year resulted in 43% tree death rate. Irrigating twice each week through the first summer after planting in spring kept all trees alive. Under limited irrigation conditions, trees from containers died sooner and more trees died than field-grown, B&B trees. Root-pruned, field-grown, B&B trees survived better than all others following transplanting. Trees planted from all nursery production methods survived and grew similarly, provided they were irrigated regularly through the first growing season. Under limited irrigation, landscape managers would obtain the most live trees by planting root-pruned, field-grown, B&B nursery stock.
The Dendro-Psychoses of J.O. Quantz
Robert Sommer
Abstract. J.O. Quantz was an early Canadian psychologist who
published an intriguing article on the origins of human attachment to trees.
Based on anthropological sources and interviews with children, the paper
is a forerunner of current evolutionary theories of tree preference.