Martin F. Quigley

Cadmium and Copper Uptake and Translocation in Five Willow (Salix L.) Species

ABSTRACT The efficacy for phytoremediation of five willow species was tested by experimental copper and cadmium uptake in a greenhouse hydroponic system. Five treatments included two concentrations (5 and 25 μM for each metal) and a control. Metal concentrations in solution as well as solution uptake were monitored. Metal resistance was assessed through effects on the dry weight of roots and shoots. The willow species tested were generally resistant of increased Cu and Cd content. Metal accumulation was found in all plant organs of all species. Growth and transpiration were not decreased by 5 μM of copper and 25 μM of cadmium in the solution for most species. 25 μM copper caused injury and reduced the dry weight for all species after 21 d. Salix nigra was highly resistant of both Cu and Cd and accumulated more metals than other species. Future field study should be conducted to confirm the findings and feasibility of the phytoremediation technology using those species.

Street trees and rural conspecifics: Will long-lived trees reach full size in urban conditions?

Urban conditions are known to affect tree growth, but not all trees respond similarly to presumed stress. I test a hypothesis that successional status of hardwood tree species, rather than taxon, will differentially affect tree size relative to age, in forest versus street plantings. In central Ohio, USA, samples (N = 230) representing 15 native tree species were matched for size between rural woodlot and city street-side conditions. Their girth was measured and their age determined by a count of annual growth rings. Age and size data were analyzed by a general linear model. Most urban trees had smaller trunk diameters than rural conspecifics of the same age. However, trees of early and mid-successional ecologies, despite smaller girth, showed no reduction in growth rate over time. Late successional species appeared to be affected by proximity to impervious areas, showing reduced growth rates, and by inference,reduced ultimate size.

Effects of Typha latifolia transpiration and harvesting on nitrate concentrations in surface water of wetland microcosms.

AbtractThis experiment tested the hypothesis that the movement of water into the soil due to macrophyte transpiration stimulates nitrate removal from wetlands. The short-term impacts of biomass harvesting upon the ability of wetlands to reduce nitrate concentrations were also investigated. Different amounts of biomass were harvested fromTypha latifolia specimens to create three treatments of varying transpiration rates. Harvesting and the resulting different rates of transpiration explained between 10 and 38% of the variation in nitrate reduction during the 10-day experiment and had significant effects upon nitrate concentrations. Greater rates of harvesting and lower rates of transpiration resulted in decreased reductions of nitrate in the surface water of the microcosms. During the first four days of the experiment, 70% and 85% rates of aboveground harvesting reduced transpiration by 63% and 91%, respectively. These changes led to respective decreases in nitrate reduction of 16% and 31% compared to unharvested treatments. Differences in nitrate reduction between the treatments were minimal in the later days of the experiment as nitrate concentrations decreased. Results support the hypothesis that water movement due to plant uptake contributes, to nitrogen removal and offers a partial explanation for increased nitrogen removal in vegetated wetland treatment systems. Decreased reduction of nitrate with greater harvesting demonstrates potential negative impacts on water quality improvement when using wetlands as bio-energy production systems.

EFFECT OF A WOODY (SALIX NIGRA) AND AN HERBACEOUS (JUNCUS EFFUSUS) MACROPHYTE SPECIES ON METHANE DYNAMICS AND DENITRIFICATION

Wetlands improve water quality through denitrification, but these ecosystems are also an important source of the greenhouse gas, methane. The objective of this research was to determine the effect of two common macrophyte species (Juncus effusus and Salix nigra) on denitrification and on the methane cycle. The research was conducted in a newly constructed wetland on the Columbus campus of The Ohio State University during two growing seasons. In the wetland, some plots were left unplanted, while others were planted with Salix or Juncus species (i.e., 3 treatments; n = 15 per treatment). For each treatment, we quantified concentrations of methane at two depths (15 and 25 cm) in the sediment, emissions of methane from the sediment and through the plants, and denitrification rates. During most of the second growing season, both species had a limited effect on denitrification and methanogenesis. The effects of the plants became evident by the end of the second growing season and during the third growing season. During the third growing season, Salix species enhanced the release of the greenhouse gas methane to the atmosphere, while Juncus limited the emission of methane. In comparison to the unplanted plots, the long-term removal of nitrate by denitrification was favored in the plots planted with Juncus and was not affected by Salix. Our study provides evidence that certain plants (such as Juncus) can be planted in constructed wetlands to favor denitrification, while buffering methane emission.

Franklin Park: 150 years of changing design, disturbance, and impact on tree growth

Urban stresses are known to affect street trees growing in spatially restricted conditions, but even in relatively large parks the cumulative effects by construction, pedestrian uses, and impacts from temporary events may have deleterious long-term effects on plant health. In Columbus, Ohio, the 93 ac (42.3 ha) Franklin Park has been subjected to major construction events and site re-configuration about once per generation—at least six times in 150 years. The first recorded shade- and ornamental tree installations occurred between 1895 and 1910. Those trees, as well as those native to the park, were mapped in 1939, 1989, and again in 2000. Testing the hypothesis that cumulative disturbance reduces tree vigor and growth rate even in open-grown conditions, tree diameters were compared over the sixty year period between 1939 and 2000. Soil compaction and percolation were measured on a 50 m grid, and maps were overlain to determine where site disturbance,buildings, utility lines, paths and pavements had occurred since 1860. Only 8% of the parks surface escaped disturbance; undisturbed areas occurred only in isolated patches. For all trees, trunk diameter increase averaged 0.5 cm/year for 61 years. While late successional species (e.g., Quercus, Acer) had growth rates less than expected for open-grown specimens, many early successional species (Celtis, Populus) were less affected. Despite availability of soil nutrients and lack of canopy or understory competition, tree health was generally poor in all size classes and the majority of the trees present in 1939 were in decline by 2000.

Does mowing height influence alkaloid production in endophytic tall fescue and perennial ryegrass

The mutualistic symbiosis following infection of tall fescue, Festuca arundinacea, and perennial ryegrass, Lolium perenne, by fungal endophyte (Neotyphodium spp.) results in the production of alkaloids that are feeding deterrents or toxic to insects and livestock. If the levels of the alkaloids can be manipulated by cultural practices in the grasses that are used for home lawns and golf courses, this could alleviate the need for pesticide applications in urban environments. We evaluated the influence of mowing height on the levels of some alkaloids in a greenhouse experiment for two consecutive months. In tall fescue, levels of four of the nine alkaloids, including one presumptive alkaloid, showed increased levels with increasing the mowing height from 2.5 to 7.5 cm. The alkaloids were ergonovine, ergocryptine, perloline methyl ether, and an unidentified alkaloid designated as unknown C. In perennial ryegrass, three out of six alkaloids, perloline methyl ether, chanoclavine, and unknown A, showed similar increases. The alkaloid levels in perennial ryegrass showed more variability than those in tall fescue between the two sampling dates. It was clear in both grasses that the relative levels of the alkaloids varied with mowing height, as well as over time.

Emergy evaluation of food production in urban residential landscapes

To transform cities from heterotrophic into sustainable ecosystems many authors have called for increased food production, including home gardening, in urban areas. We conducted an emergy analysis of four model backyard landscape plots—a conventional ornamental landscape, an intensive organic garden, an edible landscape, and a forest garden—to assess the yield and sustainability of these systems. Data were collected during the 2001 growing season and extrapolated to make a five year projection. In the 2001 season, all plots had low Emergy Yield Ratios (EYR) of between 0.0003 and 0.17 and extremely low Emergy Sustainability Indices (SI). In the five year projection, all plots still had low EYRs of between 0.0008 and 0.33 and very low SIs. These low indices are due primarily to the high levels of economic inputs required for the installation and maintenance of these plots in an urban context. Analyses performed on larger systems (households, neighborhoods and cities) containing productive landscapes such as those studied here may produce different results. Installing food-producing landscapes in urban areas without altering the networks by which such landscapes are supplied, however, may not substantially alter the heterotrophic nature of cities.