Table of Contents Catherine K. Singer and Chris A. Martin Effect of Landscape Mulches on Desert Landscape Microclimates ...................................................................... 230 Abstract. Effects of three landscape mulches: 1) composted ponderosa pine residue; 2) uncomposted shredded landscape tree trimmings; and 3) screened decomposing granite, were compared over the course of 2 years (2004 to 2005) for their ability to modify air and soil landscape microclimates in Phoenix, Arizona, U.S. Temperatures at the surface of the two organic mulches were generally higher during the day and lower at night than at the surface of either decomposing granite or soil without a mulch cover. During nighttime hours, decomposing granite mulch or soil without a mulch cover emitted more long wave radiation than the two organic mulches. Conductive heat transfer through the organic mulches was generally lower than through decomposing granite. Daytime temperatures of soil at 5 and 30 cm (2 and 12 in) depths were gener- ally lower beneath the two organic mulches than under decomposing granite mulch or soil without any landscape mulch cover. Soil covered with organic mulch evaporated less water than soil without mulch. Under desert conditions, the two organic mulches were more effective at moder- ating heat gain and water loss from soil than decomposing granite mulch because of an increased resistance to heat transfer and evaporation. Key Words. Soil Heat Flux; Soil Water Evaporation; Temperature. Richard H. Yahner, Richard T. Yahner, and Bradley D. Ross Plant Species Richness on a Transmission Right-of-Way in Southeastern Pennsylvania, U.S. Using Integrated Vegetation Management ................................................. 238 Abstract. The Green Lane Research and Demonstration Area, Montgomery County, Pennsylvania, U.S., has been studied each year since 1987, making this 21-year-old project extremely valuable as a source of information on the effects of mechanical and herbicidal maintenance on flora and fauna along an electric transmission right-of-way (ROW). In this article, our objective was to document plant species richness among treatment units and in relation to wire and border zones on the ROW. We noted the presence of plant species from late May through mid- August in 2005 and 2006 and observed 114 vascular plant species in the ten treatment units; 35 (31%) of these species were exotic. Twenty- seven (24%) species were widespread on the ROW and seven of these (26%) were exotic. The total number of species per unit ranged from 46 (40%) species in handcut units to 57 (50%) in stem–foliage spray units. Of the total number of species, 103 (90%) and 81 (71%) occurred in wire and border zones, respectively. The number of exotic species was higher in wire zones (33 [29%]) than in border zones (22 [19%]). Key Words. Exotic Species; Herbicides; Integrated Vegetation Management; Rights-of-Way; Southeastern Pennsylvania; Species Richness; Tree Control; Vegetation. Richard Stalter and Dwight Kincaid A 70-Year History of Arborescent Vegetation of Inwood Park, Manhattan, New York, U.S. ................................ 245 Abstract. The arborescent vegetation located at three sites within Inwood Park, Manhattan, New York, U.S. was sampled by the quadrat method in October 2004 and May 2005 and compared with the trees present in the same quadrats on a map of trees at Inwood Park prepared by the federal Works Program Administration in 1935. Tulip poplar (Liriodendron tulipifera) was the dominant tree at the Moist Valley and South Slope sites in 1935 and 2005, whereas oak (Quercus) was the dominant genus at Dry Ridge in 1935 and 2005. Dogwood (Cornus florida) was the dominant subcanopy tree in 1935; it was unimportant in 2005, a victim of dogwood anthracnose. In terms of ecologic dominance, there has been no change in the first ranked genera at these sites in the past 70 years. Mean tree diameter (diameter at breast height) has increased from 32.3 cm (12.9 in) to 41.8 cm (16.7 in). The three sites have experienced a parallel pattern of increase in tree size from 1935 to 2005. Nonnative trees were not important in Inwood Park in 2005. Key Words. Inwood Park; Manhattan; New York City; Urban Forests. Betsy A. Goodrich, Ronda D. Koski, and William R. Jacobi Roadside Vegetation Health Condition and Magnesium Chloride (MgCl2 ) Dust Suppressant Use in Two Colorado, U.S. Counties ....................................... 252 Abstract. Many abiotic and biotic factors affect the health of roadside vegetation, including the application of magnesium chloride (MgCl2 ) dust suppression products. Three hundred seventy kilometers (230 mi) of forested, shrubland, meadow, rangeland, riparian, and wetland road- side habitats were surveyed along major nonpaved roads in two Colorado counties. Dominant species composition and visible damages of woody road- side vegetation were quantified. The majority (72.3% to 79.3%) of roadside vegetation surveyed was considered healthy (less than 5% damage to crown or stem), depending on slope position from the road. Severely damaged (greater than 50% damage) vegetation ranged from 6.4% to 11.4% of roadside cover, with the most severely damaged vegetation occurring downslope from the road. Percent of plants with severe or moderate damage increased with increasing MgCl2 the distribution of MgCl2 Key Words. Aspen; Lodgepole Pine; Magnesium Chloride (MgCl2 application rates for roadside aspen, Engelmann spruce, and lodgepole and ponderosa pines. Further research is needed to determine ions, nutrients, and interactions between MgCl2 and incidence of potential biotic damage agents in roadside soils and plants. ); Ponderosa Pine; Road Dust Control; Road Stabilization. ©2008 | International Society of Arboriculture | ISSN:1935-5297
July 2008
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