An analysis of trees in the Chicago region of Illinois reveals that this area has about 157,142,000 trees with tree and shrub canopy that covers 21.0 percent of the region. The most common tree species are European buckthorn, green ash, boxelder, black cherry, and American elm. Trees in the Chicago region currently store about 16.9 million tons of carbon (61.9 million tons CO 2) valued at $349 million. In addition, these trees remove about 677,000 tons of carbon per year (2.5 million tons CO 2 /year)

Background and Aims: A hybrid grapevine biparental mapping population was evaluated for resistance to grape phylloxera (Daktulosphaira vitifoliae Fitch) in the greenhouse and in the field. The family (n = 125) was derived from a cross of two University of Minnesota breeding selections from a complex pedigree with multiple Vitis species. Methods and Results: The vines were evaluated for foliar phylloxera severity using visual rating in the field for multiple years. In the greenhouse, a replicated experimental design was used to quantify phylloxera severity using different traits including number of galls per plant, area under the disease progress curve, proportion of leaves with galls, average number of galls per leaf and visual rating. The plants used in the greenhouse experiment were also visually rated for root infestation. Conclusions: Quantitative trait loci (QTL) mapping for the foliar resistance traits (reduced severity) routinely identified the region spanning~10 to 30 cM on linkage group (LG) 14 to be associated with resistance, and inherited from the mother parent MN1264. The plants used in the greenhouse experiment were also visually rated for root infestation, and subsequent QTL mapping identified regions on LG 5 of the maternal map and LG 10 of the paternal map (MN1246) associated with root resistance.Significance of the Study: The new QTLs identified in this report are potential novel sources of resistance and the first report of QTL for foliar phylloxera resistance in a hybrid grapegrowing region of North America. Molecular markers linked to resistance can be utilised in marker-assisted breeding.

The generation of a single low-frequency wave (LFW) pulse by a single group of waves incident on a beach is investigated by means of laboratory experiments and a numerical model. This simplified case allows the LFW to be measured in isolation, after the incident group has passed and before there is any reflection from the wavemaker. A beach consisting of two different slopes (1:100 and 1:20) was used, and runs were made with the water level on each slope. The results were simulated using a composite numerical model, with Boussinesq equations in the deeper water and nonlinear shallow water equations in the surf zone. For some calculations, a friction term was included. For the 1:20 slope, the outgoing LFW is well predicted even without the friction term. With a 1:100 slope, a friction factor of 0.01 gave a good result, in this case reducing the amplitude of the outgoing LFW by a factor of about 2 compared with the frictionless result. The nondimensional equations show that the friction term is insignificant if the beach slope is large compared with the friction factor. Runs of the surf zone part of the model show the outgoing LFW to be correlated with the swash motion. Its amplitude is largest if the duration of the wave group is similar to the swash period of the largest wave in the group. The model also showed a slightly stronger than linear dependence of LFW amplitude on incident wave amplitude.

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