John W. Groninger

The ecology, restoration, and management of southeastern floodplain ecosystems: A synthesis

Floodplain ecosystems of the southeastern United States provide numerous services to society, but hydrologic and geomorphic alterations, agricultural practices, water quality and availability, and urban development continue to challenge restorationists and managers at multiple spatial and temporal scales. These challenges are further exacerbated by tremendous uncertainty regarding climate and land use patterns and natural variability in these systems. The symposium from which the papers in 2009 ensued was organized to provide a critical evaluation of current natural resource restoration and management practices to support the sustainability of floodplain ecosystem functions in the southeastern United States. In this paper we synthesize these concepts and evaluate restoration and conservation techniques in light of our understanding of these ecosystems. We also discuss current and future challenges and attempt to identify new approaches that may facilitate the long-term sustainability of southeastern floodplain systems. We conclude that integration of disciplines and approaches is necessary to meet the floodplain conservation challenges of the coming century. Integration will not only include purposeful dialogue between interdisciplinary natural resource professionals, but it also is necessary to sincerely engage the public about goals, objectives, and desirable outcomes of floodplain ecosystem restoration.

Community Composition and Structural Changes in a Managed Illinois Ozark Hills Forest

Abstract Forest stand dynamics were evaluated in a previously managed Quercus-Carya-dominated forest inventoried in 1980 and 2000, a period during which all active forest management was suspended and fire suppression was complete. The diameter distribution superficially resembled a stable unevenaged structure. Over the course of the study, smaller diameter classes were increasingly dominated by shade tolerant species Acer saccharum and Fagus grandifolia across all landscape positions. Diameter distribution changes varied among Quercus species with Q. alba and Q. rubra basal area increasing 63 and 45%, respectively, and Q. velutina decreasing 25% in the >43.2 cm size class. Combined Q. alba, Q. rubra and Q. velutina density decreased 56% in the <27.9 cm size classes. Transition towards a mesophyte-dominated forest is occurring across all positions in this topographically-diverse landscape, although more slowly on the drier, less productive aspects and slope positions. These changes are comparable to those reported in undisturbed forests of similar overstory composition. The results suggest that sustaining a sizeable component of the presently dominant overstory species will require remedial management strategies that take into account the regeneration requirements of Quercus, Carya and other presently dominant taxa. The decrease in Q. velutina density in the >43.2 cm size class suggests a decline in the regeneration potential of this short lived species.

Performance of Grease Abatement Devices for Removal of Fat, Oil, and Grease

This study assessed the performance of a conventional grease abatement device and the impact of internal geometry modifications on fat, oil, and grease (FOG) removal efficiency. Analysis was performed using experimental results and computational fluid dynamics (CFD) on alternative inlet, outlet, and baffle wall designs. Numerical and experimental results indicated that the conventional two-compartment design leads to substantial FOG short circuiting when operated at a 20-min hydraulic retention time (HRT). Alterations to the inlet configuration and baffle wall arrangement yielded FOG removal enhancements with the 20-min HRT that approached removal performance levels obtained with the standard configurations at the 1-h HRT. CFD simulations effectively reproduced performance trends observed on the lab-scale with the exception of simulations using a distributive inlet tee, where CFD over predicted the removal performance.

Past land use, disturbance regime change, and vegetation response in a southern Illinois bottomland conservation area1

Abstract Forested bottomland conservation areas in the midwestern and southern United States are subject to an increasingly diverse range of demands for recreational use and other ecosystem services, many dependent upon the maintenance of specific plant communities. Historical land use and other disturbances have shaped present vegetation composition, but these impacts are poorly understood. This study examined historical land use records, dendrochronological evidence, and pre- and post-tornado vegetation, with and without salvage logging, to assess forest composition changes over approximately 125 years at Mermet Lake Conservation Area in southern Illinois. This site has land use history, vegetation cover, and a management mandate common to many large river bottomland forests in the Midwest and southern USA. The vegetation of the area prior to Euro-American settlement was primarily a forest dominated by Taxodium distichum (L.) Rich. and Nyssa aquatica L. A period of drainage and conversion to agriculture began ca. 1900 and was followed by public ownership as a conservation area since 1950. Management during this latter period was characterized by partial hydrologic restoration and complete fire suppression. The post-agriculture forest was dominated by oaks (Quercus spp.) with a transition to mixed mesophytic and bottomland hardwood forests. Following a tornado, composition and diversity within the developing stand varied along a wind intensity gradient but tended toward increasing dominance of mixed mesophytic species at the expense of Quercus. Subsequent partial salvage logging further increased vegetation complexity in response to mineral soil exposure and creation of microtopographic variation. Grading and seeding of skid trails following salvage operations produced compositionally distinct vegetation communities. Increasing prevalence of the invasive exotic Microstegium vimineum (Trin.) A. Camus., especially on salvaged plots, is expected to continue to impact vegetation communities at Mermet Lake. Our results suggest that historical alterations in site hydrologic conditions, from pre-drainage to drainage to partial hydrological restoration, in combination with associated land use changes, produced drastic changes in forest community composition over the last century. Managers of this and similar bottomland forest areas need to consider disturbance regime changes and appropriate silvicultural strategies needed to create or maintain the historical range of vegetation types associated with sometimes disparate conservation objectives

Water distribution systems and on-farm irrigation practices: limitations and consequences for Afghanistan's agricultural productivity

The absence of a reliable water supply to farmers is the single most important impediment to food security and agricultural expansion in Afghanistan. Agricultural water supply and distribution systems are reviewed, and a pragmatic strategy is outlined to increase water capital and to better utilize available water. The development and dissemination of on-farm practices that improve water management through community-based approaches represent the best opportunity for improving farmer livelihoods, maintaining social stability and developing a sound agriculture-based economy in the immediate future, independent of the success or failure of national water policies.

Water for agriculture: challenges and opportunities in a war zone

Wars, drought and social collapse have greatly impaired land management and agriculture production systems in the southeastern Afghanistan provinces of Khost, Paktika and Paktya. This region has long existed with limited central government influence and remains particularly unstable. A complex physical and social geography, on-going warfare, severely limited mobility and policies poorly adapted to regional realities hamper development and reconstruction. On-farm water efficiency improvement, watershed-scale work restricted to small, socially homogeneous watersheds and word-of-mouth Afghan-to-Afghan technology dissemination are particularly important development strategies in this environment.

Reforestation Strategies Amid Social Instability: Lessons from Afghanistan

Foreign and domestic government agencies and other international organizations pursue reforestation programs in rural upper watershed areas of Afghanistan over the past decade to alleviate poverty, combat the insurgency and rehabilitate a depleted forest resource base. Popular programs incorporate cash-for-work to conduct hillside terracing, check dam construction and tree-planting for nut production, fuel wood, timber, dune stabilization, and erosion abatement. Programmatic approaches have varied as a function of accessibility, security and local objectives. Uncertain land tenure and use rights, weak local environmental management capacity, and a focus on agricultural production to meet immediate needs limit interest, nationally and locally. Unreliable security, a lack of high quality tree planting stock, limited technical knowledge and coordination among government agencies, and poor security hamper program expansion. Reforestation success would be most likely where these issues are least acute. The Afghan government should focus on supporting community based natural resource management, developing and disseminating improved conservation tree nursery strategies, and promoting watershed management schemes that incorporate forestry, range management and agronomic production. Reforestation practitioners could benefit from the human and material resources now present as part of the international war effort. Successes and failures encountered in Afghanistan should be considered in order to address similar problems in insecure regions elsewhere when reforestation may help reverse environmental degradation and contribute to broader social stabilization efforts.

Soil and Groundwater Nitrogen Response to Invasion by an Exotic Nitrogen-Fixing Shrub

Autumn-olive (Elaeagnus umbellata Thunb.) is an invasive, exotic shrub that has become naturalized in the eastern United States and can fix nitrogen (N) via a symbiotic relationship with the actinomycete Frankia. Fixed N could potentially influence nutrient cycling rates and N leaching into soil water and groundwater. In situ net N mineralization, net nitrification, and net ammonification rates, as well as soil water and groundwater nitrate N (NO(3)-N) and ammonium N (NH(4)-N) concentrations, were measured under autumn-olive-dominated and herbaceous open field areas in southern Illinois. Soil net N mineralization and net nitrification rates were higher under autumn-olive compared with open field (p < 0.05) and could be driven, in part, by the relatively low C/N ratio (11.41 +/- 0.29) of autumn-olive foliage and subsequent litter. Autumn-olive stands also had greater soil water NO(3)-N (p = 0.003), but soil water NH(4)-N concentrations were similar between autumn-olive and open field. Groundwater NO(3)-N and NH(4)-N concentrations were similar beneath both types of vegetation. Groundwater NO(3)-N concentrations did not reflect patterns in soil N mineralization and soil water NO(3)-N most likely due to a weak hydrologic connection between soil water and groundwater. The increased N levels in soil and soil water indicate that abandoned agroecosystems invaded by autumn-olive may be net sources of N to adjacent terrestrial and aquatic systems rather than net sinks.

Survival and Genet Growth and Development of Field-Planted Giant Cane (Arundinaria gigantea) over Time in Southern Illinois

Abstract The drastic loss of giant cane (Arundinaria gigantea) -dominated communities (canebrakes) in southeastern North America has spurred great interest in habitat restoration. We report on two giant cane restoration studies that investigate the effects of collection source, rhizome propagule morphological characteristics and type (greenhouse-grown containerized stock plants or bare rhizomes), site, and time on genet survival and growth. Survival over the two studies (after three and five years) differed by propagule collection source, was marginally greater when planting older containerized stock, and varied between sites. Although field survival tended to be somewhat greater for greenhouse-grown containerized stock in comparison to bare rhizomes, overall survival was similar for both stock types when accounting for mortality of planted rhizomes in the greenhouse. The number of culms, their height, and spread of the genets increased over time and differed by planting stock type in each study. At Beccas Tract, cane genet growth ranged from a mean of 1.4 ± 0.1 culms that were 41.7 ± 1.8 cm tall with essentially no spread after the first growing season to a mean of 80.6 ± 7.6 culms that were 99.8 ± 2.8 cm tall with a spread of 212.1 ± 19.6 cm after five years. Giant cane rhizome sections initially grown in a greenhouse or planted directly in the field can be used to establish canebrakes in a framework that is operationally feasible for large-scale restoration.

Effects of Diquat Applied to Exposed Roots of Black Willow

Practical and environmentally benign methods are continually being sought to chemically control tree root obstructions in municipal and agricultural drainage systems. In a greenhouse study designed to simulate sewer line conditions, diquat applications of 0.48 and 0.96 g ai/L resulted in partial and complete control, respectively, of treated roots of black willow (Salix nigra Marsh.). The higher rate significantly reduced the number and weight of new roots developing proximal to the area of herbicide exposure, suggesting that diquat was translocated. No damage to the shoot was observed, and diquat activity were unaffected by the presence of clay particles. These results suggest a previously undocumented mode of action for diquat that may have use in the management of tree root obstructions in municipal sewers and other drainage systems.