Janette R. Thompson

Root system morphology of Quercus rubra L. planting stock and 3-year field performance in Iowa

On 3 sites, 3-year performance of 1+0 northern red oak (Quercus rubra L.) seedlings was evaluated with respect to initial root system grade. Seven hundred twenty nursery-run bareroot northern red oak seedlings were graded according to numbers of large (>1mm) first-order lateral roots and outplanted in spring 1987 on eight 90-tree plots distributed among three sites in central Iowa. Survival, height growth, and diameter growth were significantly greater for seedlings with 10 or more large first-order lateral roots than for seedlings with 4 or fewer. Seedling survival and growth were significantly and positively related to initial root grade. First-year height growth, however, was significantly and negatively correlated with initial height. Combined results for seedling survival and growth indicated that red oak seedlings with five or more large first-order lateral roots have a greater probability of success both in terms of survival and early growth than do those with four or fewer first-order lateral roots.

Effect of density control and undercutting on root morphology of 1+0 bareroot hardwood seedlings: five-year field performance of root-graded stock in the central USA

The Hardwood Quality Nursery Cooperative (bareroot forest nurseries in 5 midwestern states) initiated a series of studies in 1987 to evaluate red oak (Quercus rubra L.), and black walnut (Juglans nigra L.) seedling performance as a function of cultural treatments and seedling root system morphology.Seedlings were grown at three densities (32, 64, and 128 stems m-2for red oak; 32, 64, and 96 stems m-2for black walnut), and half of the density plots were undercut. Seedlings received fertilizer, weeding, and irrigation treatments customary to their respective nurseries. Seedlings were lifted, measured, and outplanted in their respective states as completely random individual tree plots during spring 1988. Survival, height, and diameter were evaluated annually through 1992.Seedling height, diameter, and number of permanent first-order lateral roots (FOLR) decreased with increasing bed density. At a given density, undercutting produced smaller seedlings (for both height and diameter) that had greater numbers of FOLR. Numbers of FOLR influenced seedling performance after outplanting. Red oak seedlings with at least 5 FOLR and black walnut with at least 7 FOLR had better survival and growth than seedlings with fewer roots.

Factors related to tree growth across urban-rural gradients in the Midwest, USA

Several environmental factors influence tree growth at any site. The objective of this study was to examine the relationship between biotic and abiotic factors and tree growth rate (mean ring width averaged over the last 10 years) in settings ranging from urban to rural. Six “clusters”, each with five communities and two rural parks, were sampled in Illinois, Iowa, Minnesota, Missouri, and Wisconsin, for a total sample of 320 trees. Within each community, trees in parks, and along residential and commercial streets were sampled. Five species were sampled: silver maple (Acer saccharinum L.), honeylocust, (Gleditisia triacanthos L.), hackberry (Celtis occidentalis L.), black maple (Acer nigrum Michx F.), and basswood (Tilia americana L.). Factors were investigated for three scenarios: (i) all trees sampled in all clusters, (ii) a single species, all clusters, and (iii) all species, a single cluster.Baseline variables (cluster, place population, site, species, and age) accounted for 49–71% of observed variation in growth rate. Combined biotic factors accounted for 5 to 6% of observed variation. For all species in a single cluster, combined abiotic factors accounted for 11% of observed variation. Biotic factors related to growth rate detected using multivariate analyses included number of other trees within 9 m, presence of disease and insects, and human-induced mechanical injury. Abiotic factors that were related to tree growth included presence of pavement and core bulk density. For trees in rural parks, number of other trees within 20 m, and for trees in both rural and community parks, number of other trees within 9 m of sample trees were associated with decreased growth rate.

Land Use, Stream Habitat and Benthic Invertebrate Assemblages in a Highly Altered Iowa Watershed

Abstract Knowledge of relationships between land cover (i.e., land use) and abiotic and biotic features of headwater streams enhances our ability to predict and effectively assess conditions in a variety of aquatic ecosystems. We evaluated land use effects on stream condition in an Iowa watershed dominated by intensive row crop agriculture and low- intensity urban development by quantifying relationships among land cover, stream invertebrate assemblages and other stream biophysical characteristics (i.e., invertebrate habitat) at 29 sites. On average, 81% of subbasin land cover was agricultural and 6% of land cover was urban across study sites. High nitrate concentrations (range  =  5.6–29.0 mg/L) and high relative abundance of oligochaetes and chironomid midges reflected degraded conditions at all sites. However, agriculture and urban land use appeared to have different effects on stream features. Nitrate concentrations were positively related to agricultural land cover, and turbidity and nitrate concentrations were negatively related to urban land cover (P ≤ 0.05). Invertebrate densities and taxonomic diversity (i.e., total taxa richness, % EPT) were also positively related to agricultural land cover and negatively related to urban land cover. Regardless of land use, highest invertebrate abundance and taxonomic diversity occurred at sites with abundant coarse particulate organic matter, plants and coarse inorganic substrate. Relationships between land cover and invertebrate variables were strong at both local and subbasin measurement scales. Based on invertebrate assemblages, which integrate multiple instream features, we conclude that urban land use had greater adverse effect on stream condition than agriculture in our study watershed. Although impacts of urbanization on stream invertebrates frequently exceed effects of agriculture, this has not previously been demonstrated in Iowa or other Midwestern landscapes so heavily dominated by agriculture.

Learning about restoration of urban ecosystems: a case study integrating public participation, stormwater management, and ecological research

Restoration of ecosystem functions in urban environments is made challenging by 1) a public that often lacks understanding of ecological principles, 2) inadequate evidence of the effectiveness of restoration practices, and 3) difficulty integrating social and biophysical factors in studies of urban ecosystems. This paper describes a case study in which potential solutions to these challenges were explored. We facilitated collaborative learning through public participation in the design and implementation of an urban riparian buffer along a headwater stream in a neighborhood park, a process that was informed by ecological research. Learning outcomes were evaluated using surveys and qualitative assessment of discussion. Results indicated that participants’ knowledge about water quality problems associated with urbanization, stormwater, and nonpoint-source pollution increased, familiarity with stormwater management practices increased, and perceptions about the importance of stream ecosystem functions changed. In-stream monitoring of sediment delivery, as well as direct measurements of buffer infiltration capacity, provided early evidence of buffer effectiveness in prevention of sediment inputs to the stream and absorption of runoff from surrounding surfaces. This study provides a useful model for integration of collaborative learning through participation, ecological restoration, and ecological research in an urban setting. Elements deemed essential to success of this model included an opportunity for dialog focused on a specific natural feature, sustained interaction between participants and researchers, opportunities for hands-on participation by urban residents, and flexibility in restoration practice installation.

Vegetative buffers for fan emissions from poultry farms: 2. ammonia, dust and foliar nitrogen

This study evaluated the potential of trees planted around commercial poultry farms to trap ammonia (NH3) and dust or particulate matter (PM). Norway spruce, Spike hybrid poplar, hybrid willow, and Streamco purpleosier willow were planted on five commercial farms from 2003 to 2004. Plant foliage was sampled in front of the exhaust fans and at a control distance away from the fans on one turkey, two laying hen, and two broiler chicken farms between June and July 2006. Samples were analyzed for dry matter (DM), nitrogen (N), and PM content. In addition, NH3 concentrations were measured downwind of the exhaust fans among the trees and at a control distance using NH3 passive dosi–tubes. Foliage samples were taken and analyzed separately based on plant species. The two layer farms had both spruce and poplar plantings whereas the two broiler farms had hybrid willow and Streamco willow plantings which allowed sampling and species comparisons with the effect of plant location (control vs. fan). The results showed that NH3 concentration h− 1 was reduced by distance from housing fans (P ≤ 0.0001), especially between 0 m (12.01 ppm), 11.4 m (2.59 ppm), 15 m (2.03 ppm), and 30 m (0.31 ppm). Foliar N of plants near the fans was greater than those sampled away from the fans for poplar (3.87 vs. 2.56%; P ≤ 0.0005) and hybrid willow (3.41 vs. 3.02%; P ≤ 0.05). The trends for foliar N in spruce (1.91 vs. 1.77%; P = 0.26) and Streamco willow (3.85 vs. 3.33; P = 0.07) were not significant. Pooling results of the four plant species indicated greater N concentration from foliage sampled near the fans than of that away from the fans (3.27 vs. 2.67%; P ≤ 0.0001). Foliar DM concentration was not affected by plant location, and when pooled the foliar DM of the four plant species near the fans was 51.3% in comparison with 48.5% at a control distance. There was a significant effect of plant location on foliar N and DM on the two layer farms with greater N and DM adjacent to fans than at a control distance (2.95 vs. 2.15% N and 45.4 vs. 38.2% DM, respectively). There were also significant plant species effects on foliar N and DM with poplar retaining greater N (3.22 vs. 1.88%) and DM (43.7 vs. 39.9%) than spruce. The interaction of location by species (P ≤ 0.005) indicated that poplar was more responsive in terms of foliar N, but less responsive for DM than spruce. The effect of location and species on foliar N and DM were not clear among the two willow species on the broiler farms. Plant location had no effect on plant foliar PM weight, but plant species significantly influenced the ability of the plant foliage to trap PM with spruce and hybrid willow showing greater potential than poplar and Streamco willow for PM2.5(0.0054, 0.0054, 0.0005, and 0.0016 mg cm− 2; P ≤ 0.05) and total PM (0.0309, 0.0102, 0.0038, and 0.0046 mg cm− 2, respectively; P ≤ 0.001). Spruce trapped more dust compared to the other three species (hybrid willow, poplar, and Streamco willow) for PM10 (0.0248 vs. 0.0036 mg cm− 2; P ≤ 0.0001) and PM> 10 (0.0033 vs. 0.0003 mg cm− 2; P = 0.052). This study indicates that poplar, hybrid willow, and Streamco willow are appropriate species to absorb poultry house aerial NH3–N, whereas spruce and hybrid willow are effective traps for dust and its associated odors.

An investigation of water nutrient levels associated with forest vegetation in highly altered landscapes

Stream pollution by nutrient loading is a chronic problem in the Midwest, United States, and greater impacts on water quality are expected as agricultural production and urban areas expand. Remnant riparian forests are critical for maintaining ecosystem functions in this landscape context, allowing water infiltration and capture of nutrients before they are lost from the system. Our objective was to identify linkages between riparian forest plant community composition and water quality in remnant forested headwater streams. We identified watersheds with embedded headwater streams in three land use categories: grazed, urban, and preserved. We assessed plant community composition and nutrient storage. We sampled the forest streams to monitor discharge rates and sediment, nitrogen (N), and phosphorus (P) loads. Herbaceous communities in preserved riparian forests had more native specialist species than urban or grazed sites. Plant N content was higher in preserved forests (17.6 kg ha−1 [15.7 lb ac−1]) than grazed (12.5 kg ha−1 [11.2 lb ac−1]) or urban forests (10.5 kg ha−1 [9.4 lb ac−1]). Conversely, stream water total N delivery was higher in urban watersheds (0.043 kg ha−1d−1[0.038 lb ac−1day−1]) than preserved (0.026 kg ha−1d−1 [0.023 lb ac−1day−1]) or grazed watersheds (0.02 kg ha−1d−1 [0.018 lb ac−1day−1]). Stream water nitrate (NO3-N) concentration and total P delivery were highest for streams in urban areas. The most pronounced differences for plant composition and stream discharge and pollutant loads were between preserved and urban forests. Seasonal patterns were variable. We detected a weak negative but seasonally important relationship between plant N content and stream water N. We did not detect a similar relationship for P, which may indicate saturation of this nutrient in the watershed system. Detailed knowledge about relationships between land use, plant community composition, and water quality outcomes could be used to target forest restoration efforts in landscapes highly impacted by humans.

Restoration of herbaceous woodland plants: persistence, growth, and reproductive success of local and non-local propagules

Restoring the forest herbaceous layer in remnant forests throughout the Midwestern United States (U.S.) is limited by the lack of seed and propagules for many plant species. As a result, restorationists often have limited material to work with and must seek out plant material at a regional rather than a local scale, without knowing whether regional provenances are ecologically appropriate. We conducted greenhouse and field experiments to examine persistence, growth, and reproduction of three herbaceous perennials (wild ginger, Virginia waterleaf, and James’ sedge) that could be used for restoration. The greenhouse experiment represented a common garden and was conducted to identify whether there were genetic differences in morphological characters between local plants and non-local transplants from commercial nurseries. The two-year field study was conducted to determine whether any genetic differences noted in the greenhouse persisted in a natural setting, and also to determine what planting density (two or five individuals in a 0.25 m2 plot) would be sufficient for the plants to establish. In the greenhouse, growth and reproductive measures for non-local plants were generally equal to or greater than those of local plants. However, we found the reverse for many traits, particularly related to reproduction, in the field during year two. In natural field conditions local plants had equal or greater vegetative growth and reproduction than non-local plants, although both had similar persistence. Further, similar persistence and growth in low- and high-density field plots suggested that a limited number of transplants would be adequate for successful establishment of non-local transplant stock.

Stakeholders’ Perceptions of Native Plants and Local Ecotypes in Ecological Restoration

Many scientists and land managers recommend using local ecotypes for restoration projects. However, there is not a scientific consensus on what constitutes “local.” To gain information about production and use of locally sourced plant material, we surveyed two stakeholder groups, conservation professionals and nursery professionals, to learn if there were differences between these stakeholder groups in terms of use, sale, or perception of native and local ecotype plant material. Our survey results indicated that both conservation and nursery professionals are aware of the ecological and functional value of native plant communities, and are also familiar with associated plant sourcing issues. However, nursery professionals provide less local ecotype and source-certified plant material in their businesses than would meet the need expressed by conservation professionals for these materials. Conservation professionals also indicated that their organizations did not necessarily have specific guidelines for sourcing local ecotype native plant material. Although nursery professionals are aware of restoration techniques and the usefulness of local ecotypes, this does not appear to translate into provision of larger quantities of native, local ecotype, or source-certified plant material. We found that members of both stakeholder groups rely on trusted authorities and professional training for information, presenting an opportunity to reach both groups through combined workshops to encourage communication and facilitate availability of native plants for restoration.

Integrating Wildlife Conservation into Urban Planning

Conservation of wildlife at the scale of cities and metropolitan areas, particularly for species that are “urban avoiders,” will require identification, restoration, or preservation of adequate areas of key habitats. Connections between these habitats and to their natural disturbance regimes, all within the context of rapidly changing urban landscapes, must also be maintained. This necessitates the integration of concepts, knowledge, and practice from landscape ecology, conservation biology, and urban planning to successfully engage in local and regional processes that support wildlife-friendly urban growth. In this chapter, we review the broad-scale effects of urbanization on wildlife and relevant principles from conservation biology and urban planning, and propose wildlife zoning within a green infrastructure framework to integrate wildlife conservation into urban planning. Two case studies describing regional-scale urban conservation efforts––the Sonoran Desert Conservation Plan, and the Chicago Wilderness––are offered as examples of integrative, collaborative efforts to conserve wildlife in large metropolitan areas.