1. Biofuel production from cellulosic feedstocks may increase during the next century.To be sustainable, this production should protect environmental quality and biodiversity. Fertilized mixed-species prairie can deliver substantial quantities of cellulosic ethanol per unit land area with minimal losses of NO 3 -N in drainage water, but the long-term maintenance of biodiversity in such systems has been uncertain.2. We report how nitrogen, phosphorus, and potassium fertilizer application, precipitation, and time affected the species composition and productivity of reconstructed prairie communities harvested annually as biofuel feedstocks over a 9-year period.3. Results indicated that both precipitation and fertilizer application drove aboveground biomass production, with the greatest response to fertilizer occurring in wetter than average years. Fertilization reduced species richness, but increased species evenness. Consequently, Simpson's diversity index did not differ between the fertilized and unfertilized communities, though it declined in both communities over time. 4.A total of 59 plant species was recorded, with eight of them explaining most of the differences in vegetation cover between the fertilized and unfertilized treatments.After 9 years, the high fertility community was dominated by the C4 grass Andropogon gerardii, the C3 grass Elymus canadensis, and the non-leguminous forbs Heliopsis helianthoides, Helianthus maximiliani, and Monarda fistulosa, whereas the low fertility community was dominated by the C4 grasses A. gerardii and Sorghastrum nutans, the C3 grass E. canadensis, and the non-leguminous forb M.fistulosa. Fertilization increased the abundance of flowering forbs available to pollinators in the early, middle and late portions of the growing season. Synthesis and applications.Results of our study suggest that maintenance of reasonably high levels of productivity and biodiversity are possible in fertilized prairie communities harvested annually for bioenergy, with plant cover more evenly distributed among different functional groups. In the future, if policy and markets favour biofuels and better delivery of ecosystem services from harvested land, prairie-based feedstocks could become part of a renewable energy portfolio that fosters biodiversity and contributes to the provision of floral resources for pollinators. K E Y W O R D Sbiofuel, cellulosic ethanol, community dynamics, prairie vegetation, productivity, soil fertility, species diversity, succession | 331Journal of Applied Ecology KORDBACHEH Et Al.

As landscapes have become increasingly dominated by intensive agricultural production, plant diversity has declined steeply along with communities of pollinating insects including bees. Semi-natural habitats, such as field edge meadows and hedgerows, can be maintained to provide a diversity of flowering plants that can increase floral resources required by bees. An additional habitat enhancement practice is that of sowing strips of native prairie vegetation within row-cropped fields. In this study, conducted in Iowa, USA, we found that increases in both the abundance and diversity of floral resources in strips of native prairie vegetation within agricultural production fields greatly and positively influenced the bee community. The benefits to the bee community were important for both common and uncommon species and the effect may be strongest early in the season. Using networks of co-occurrence between plant and bee species, we were able to identify two native prairie plants, Ratibida pinnata and Zizia aurea , as potentially keystone resources that can be used to support native bees. When we evaluated the effect of reconstructed prairie strips on bees in the context of the surrounding landscape, we found that these conservation practices had positive effects on bees in agriculturally-dominated areas and that these effects were detectable in low to high complexity landscapes with 8–69% natural habitat. In landscapes dominated by crops with few pollen and nectar resources the inclusion of native prairie strips can buffer the decline of bees and effectively increase bee abundance and diversity.

The experiment was conducted under a controlled environment to study the effects of different temperature regimes (15/10°C, 20/15°C, and 25/20°C day/night) and sowing depths (0, 2, 4, and 6 cm) on the seedling emergence and early growth (height gain) of wheat (cv. Marvdasht) and wild barley (Hordeum spontaneum).The cumulative emergence and plant height gain over time were modeled with the use of a logistic function. For a particular temperature regime, the maximum percentage emergence (Emax) of wheat was higher than that of wild barley across all sowing depths. The maximum and minimum Emax values for both species occurred at 20/15°C and 25/20°C, respectively.The time taken to reach 50% of the Emax (i.e. E50) increased with the sowing depth in both species under all temperature regimes. The E50 of wild barley was greater than that of wheat for all temperature regimes, with maximum differences observed at 20/15°C. The greatest maximum plant height (Hmax) was observed at the surface planting for both plants. The Hmax was reduced at temperatures either lower or higher than 20/15°C, with a more notable reduction in wild barley.At all temperature regimes, the time taken to reach 50% of the Hmax (i.e. H50) increased linearly with the sowing depth but, at higher temperatures, the accelerated growth rate reduced the H50.The wild barley seedling emergence and height gain rate, as expressed relative to those of wheat, revealed the highest superiority of wheat over wild barley at 25/20°C and the sowing depth of 4 cm.

Diamond grinding is a concrete pavement maintenance technique, and concrete grinding residue (CGR) is the byproduct. Concrete grinding residue deposited along roadsides affects soil chemical properties, but impacts of CGR on soil physical properties and plant growth are rarely studied. In this study, a controlled field experiment was performed to determine the influence of CGR on selected soil physical properties (i.e., bulk density [r b ], saturated hydraulic conductivity [K s ], and water infiltrability [I t ]) and on plant biomass and plant coverage under four application rates (0, 2.24, 4.48, and 8.96 kg m −2 ). Field measurements were performed before the CGR applications, and 1, 7, and 12 mo after the CGR applications. No significant CGR effects on soil physical properties were detected. The r b was relatively stable for all of the treatments, whereas some nonsignificant variations (e.g., 10-30% of mean K s values and mean I t values among four CGR rates) were found. Plant biomass with a CGR rate of 2.24 kg m −2 tended to be 10 to 40% larger than biomass in the control treatment, whereas plant biomass with a CGR rate of 8.96 kg m −2 tended to be ?10% smaller than the control treatment. Concrete grinding residue had no significant effects on plant coverage, richness, Simpson's diversity, and evenness. Thus, CGR applications up to 8.96 kg m −2 did not significantly affect soil physical properties and plant growth in this controlled field study. This study can serve as a reference for results obtained from roadsides in Minnesota and Iowa that receive CGR applications.Abbreviations: CGR, concrete grinding residue; EC, electrical conductivity; RCBD, randomized complete block design.

Concrete grinding residue (CGR) is a byproduct of diamond grinding, a road surface maintenance technique. Direct deposition of CGR along roadsides may influence plant growth, which has not been fully studied. Particularly, systematic experiments of CGR effects on selected common prairie species growth under controlled environments are rarely reported. Thus, in this study, a greenhouse experiment was performed to determine CGR effects on seedling emergence and aboveground biomass for four roadside prairie species: Indian grass, Canada wild rye, partridge pea, and wild bergamot. Nicollet loam and Hanlon fine sandy loam were used, and CGR of 4 rates, 0, 2.24, 4.48, and 8.96 kg m−2, were applied in two ways, either mixed with the soil or applied on the soil surface. Multiple comparisons indicate that CGR produced mixed impacts on seedling emergence, depending on plant species, while aboveground biomass is not significantly influenced by CGR in general. ANOVA analysis with stepwise linear regression indicates that CGR had no uniform effects on seedling emergence, and CGR impacts should be studied for specific plant species and soil types. In conclusion, while CGR may lead to negative environmental issues on roadside plants depending on the plant species and soil types, if aboveground biomass is a major consideration, CGR effects are negligible. This study provides reference information for regulating CGR depositions along roadsides. Future studies may focus on investigating the relationship between CGR effects on seedling emergence and species succession in actual roadside environments.