Article Figures & Data
Tables
- Table 1.
Communities in Iowa where trees were sampled by location (quadrant) and by community population level. The total number of sample trees in each community is indicated parenthetically following the community name. In all communities, trees sampled were located in public spaces, except for West Okoboji, where residential trees were evaluated.
Community population category Quadrant Northeast Northwest Southeast Southwest >10,000 Waterloo (58) Sioux City (57) Iowa City (36) Ankeny (46)
Des Moines (141)2,000–10,000 Maquoketa (35) Webster City (57) Pella (46) Johnston (48) Eldora (70) Rock Valley (50) North Liberty (57) Clarinda (61) <2,000 Calmar (25) West Okoboji (27) Delta (14) Lenox (22) Colesburg (32) Holstein (34) Baxter (6) Treynor (10) - Table 2.
Taxa represented in the sample of new community trees in Iowa, number of specimens of each, and communities in which they were part of the sample. Malus spp. and Fraxinus pennsylvanica were the only taxa sampled in all communities.
Species (group) Number of trees in 1998 Number of communities species was sampled in Abies concolor Lindl. 10 1 Acer × freemannii 12 4 Acer tataricum L. subsp. ginnala Maxim. 8 2 Acer nigrum Michx. 7 3 Acer platanoides L. 36 10 Acer rubrum L. 47 10 Acer saccharinum L. 9 7 Acer saccharum Marsh. 46 11 Amelanchier arborea Michx. 7 2 Betula nigra L. 20 5 Celtis occidentalis L. 22 5 Cercis canadensis L. 8 2 Craetagus phaenopyrum L. 17 5 Cornus florida L. 3 1 Fraxinus americana L. 17 4 Fraxinus pennsylvanica Marsh. 107 21 Gingko biloba L. 2 2 Gleditsia triacanthos L. var inermis Willd. 33 7 Gymnocladus dioicus L. 1 1 Koelreuteria paniculata 1 1 Malus spp. 215 21 Picea glauca Moench 16 5 Picea mariana Mill. 12 1 Picea pungens Englm. 2 2 Pinus strobus L. 5 1 Pinus sylvestris L. 24 2 Populus alba × P. grandidentata 8 1 Prunus spp. 12 5 Pyrus spp. 25 5 Quercus alba L. 2 2 Quercus bicolor Willd. 8 3 Quercus macrocarpa Michx. 11 9 Quercus palustris Muenchh. 8 4 Quercus rubra L. 30 10 Salix babylonica L. 1 1 Syringa reticulata 27 5 Thuja occidentalis L. 9 2 Tilia americana L. 49 10 Tilia cordata Mill. 4 3 Ulmus americana cv. Liberty 1 1 - Table 3.
Values of the reciprocal of Simpson’s Diversity Index (SDI) and tree survival, for each community (one large, two medium, and two small communities) and by quadrant. Standard errors for marginal means of Simpson’s index are included. No significant differences were detected for either diversity or survival between quadrants or by community size.
Community population category Quadrant Average for community size Standard error of marginal mean (SDI) NE NW SE SW >10,000 Diversity 7.06 8.14 2.68 3.81 6.94* 5.81 1.53 Survival (%) 84 84 94 89 98* 92 2,000–10,000 Diversity 12.42 2.69 6.75 6.79 5.16 3.83 6.84 13.48 7.24 1.16 Survival (%) 91 91 100 98 87 90 87 92 92 <2,000 Diversity 4.08 4.76 9.10 7.70 6.88 2.46 1.50 4.00 5.06 1.16 Survival (%) 92 89 100 59 94 85 100 90 88 Average for quadrant Diversity 7.11 5.00 4.93 7.12 Survival (%) 89 88 94 93 Standard error of SDI marginal mean 1.54 1.54 1.54 1.34 ↵*Two large communities were sampled in the southwest quadrant.
- Table 4.
Percentage of sample population represented by the ten most common taxa, their individual survival rates, and mean height, diameter, and crown width with related standard errors as measured in spring 2000. Together these taxa make up approximately 70% of the sample population.
Taxa % of population % survival Height, m (S.E.) Diameter, mm (S.E.) Crown, m (S.E.) Crabapple 24 91 3.6 (0.6) 56 (19) 2.8 (0.7) Green ash 12 88 5.6 (1.2) 83 (31) 3.2 (0.9) Red maple 5 73 4.8 (1.3) 60 (14) 2.3 (0.6) Sugar maple 5 78 5.1 (1.4) 65 (32) 2.4 (0.9) Basswood 5 73 4.8 (0.9) 80 (15) 2.8 (0.6) Norway maple 4 89 5.1 (1.0) 78 (24) 2.9 (0.9) Honeylocust 4 88 5.3 (0.6) 79 (9) 4.1 (0.8) Red oak 3 88 4.5 (1.2) 60 (17) 2.7 (0.6) Japanese tree lilac 3 100 2.8 (0.5) 41 (15) 1.5 (0.2) Ornamental pear 3 78 5.0 (1.1) 78 (18) 2.9 (0.9) - Table 5.
Ranges and averages for incremental height and diameter growth rates for recently planted trees measured in Iowa and growth rates reported in the literature (sources noted as footnotes below table) for young trees.
Height (cm yr–1) Diameter (mm yr–1) Range Average Range Average Measured in Iowa 17–53 29 5.0–13.0 8.0 Published 5–60z 27 3.8–16.0y 7.9 ↵zIncludes data for shoot extension from Kjelgren and Clark 1992 (sweetgum trees in Seattle); Rhoads et al. 1981 (several species in Philadelphia); and Buckstrup and Bassuk 2000 (hackberry, hophornbeam, and swamp white oak in Ithaca, New York), and estimates for height growth of young trees from Frelich 1992 (12 species, Minneapolis).
↵yIncludes data from Neal and Whitlow 1997 (willow oak in Washington, D.C.); Rhoades and Stipes 1999 (nine different species in Virginia); Kjelgren and Clark 1992 (as above); Frelich 1992 (as above), Jo and McPherson 1995 (several young hardwood species in Chicago); and Nowak et al. 1990 (black locust, southern magnolia, and London plane tree in California).
- Table 6.
Total estimated pollution removal (kg yr–1) and associated monetary value (dollars yr–1) for 879 street trees in Iowa during nonprecipitation periods (dry deposition) in 2000. Monetary value of pollution removal by trees was estimated using the median externality values for the United States for each pollutant (Murray et al. 1994). Externality values for ozone were set to equal the value for NO2.
Pollutant Removal (kg yr–1) Value (US$ yr–1) Ozone 10.2 68.6 Particulate matter < 10 μz 6.4 28.8 Nitrogen dioxidey 2.5 16.7 Sulfur dioxide 1.7 2.8 Carbon monoxide 0.4 0.4 Total 21.2 117.3 ↵zAssumes 50% re-suspension of particles.
↵yBecause there was no complete data set on nitrogen dioxide (NO2) concentrations in Iowa, estimates of NO2 removal by trees in Iowa were based on removal rates for trees in Omaha, Nebraska in 1994 (0.73 g/m2 of canopy cover). This estimate is reasonable due to geographical proximity of Omaha to Iowa; also, removal rates in Omaha were relatively low compared to data from other cities in the United States.