<p> Nitrogen (N) fixing trees are commonly used to promote forest restoration in disturbed areas because they can quickly recreate forest canopy structure. That structure in turn is hypothesized to attract animal seed dispersers and create enough shade to reduce undesirable species (particularly grasses). Yet N-fixers tend to increase soil N availability, which could facilitate the spread of nitrophilous invasive species. This dissertation evaluates the long-term consequences for understory community composition of establishing three N-fixing tree species (<i>Acacia koa, Sophora chrysophylla</i>, and <i>Morella faya</i>) after exotic grass-fueled fire in the seasonally dry subtropical woodland in Hawaii. To understand the restoration potential of these species, I compared discrete single-species stands of N-fixing trees in burned areas to both an intact native woodland and burned, open sites with no tree cover. Although N-fixing species are often assumed to be ecologically similar, trait variation among N-fixing trees in this system was strong enough to differentiate understory communities among stands of the three N-fixer species. To understand the mechanisms driving differences in understory composition among site types, particularly among N-fixing trees, I characterized the abiotic environment created by these species in terms of light and N availability, both of which were important drivers of understory community composition. High light and N availability were associated with greater exotic species cover and unique exotic species. Surprisingly, N availability was highest and N cycled fastest beneath the relatively slow-growing <i>S. chrysophylla </i> despite having much lower litter-N inputs than the faster-growing <i> A. koa</i> and <i>M. faya</i>. In this study, fast N-cycling was associated with high specific leaf area, high foliar N content and low foliar lignin:N. These traits are consistent with fast leaf economic spectrum traits in the general ecological literature, but this approach has not previously been applied to distinguish among N-fixing trees. Native Hawaiian dry forest understory recovery, particularly that of woody species, was limited throughout the burned area regardless of canopy cover. To determine what limits native shrub recovery, I sampled the seed bank and recorded natural seedling germination. I also planted native seedlings into the understory of all site types and either removed or left intact the invasive grass grasses present in the understory. I found that native shrubs were limited by both seed availability and competition with exotic grasses. Although outplant survival did not vary by N-fixer species identity, differences in the mechanisms by which each N-fixing species limited native seedling survival likely play a role in understory community assembly long-term. When restoration occurs in the context of secondary succession, prioritizing the creation of forest structure using N-fixing trees, particularly open-canopied fast-cycling species, such as <i>S. chrysophylla</i>, could make full community recovery more difficult by promoting rather than suppressing exotic grasses.</p><p>

The input of emerging pollutants into the natural environment is of considerable concern due to their potential implications for the health and development of humans and wildlife. Knowledge of the occurrence and removal (by sewage treatment) of these chemicals is limited and there is a need for these to be investigated if the transport and fate of these chemicals is to be better understood. To develop our understanding, reliable, accurate and precise measurements of these compounds at the very low (often sub-nanogram) concentrations at which they may be found, and may still be toxic, is crucial. However, as a result of the increasing international concern, increasing research attention has led to a large number of analytical techniques described as being suitable for the analysis of these compounds; this fragmentation and lack of collaborative focus is likely to have resulted in a lack of refinement of the techniques employed. In this research, a number of these proposed analytical and sample pre-treatment techniques have been assessed, both by internal experimentation and through inter-calibration with collaborating laboratories, to identify which techniques are best suited to further development for research in this area, and have subsequently been optimised, to examine the removal efficacy of traditional and novel sewage treatment techniques, and to monitor EDC and Pharmaceutical concentrations in several UK rivers. Monitoring of the river Ray, Swindon, UK over a period of three years, using spot-sampling and 24-hour and 7-day integrated sampling, combined with solid-phase extraction (SPE) followed mass spectrometric analyses, showed stable EDC and pharmaceutical levels, typical of comparable rivers throughout the EU, but with a significant reduction in concentrations after the installation of a granular activated charcoal plant at the Rodbourne Sewage Treatment Works (STW) of which the river Ray is a conduit. These results were in agreement with results from analyses biological assays, such as yeast estrogen screening performed independently by another laboratory.

För att bemöta krav och rekommendationer som ställs på avfallsinsamlingen behöver den nuvarande manuella insamlingen förändras, eller bytas ut. Ett alternativ är att genomföra åtgärder så att en manuell insamling med avfallskärl placerade i soprum kan fortsätta och tömmas med hjälp av traditionella sopbilar. Ett andra alternativ är att ersätta den manuella insamlingen med en stationär sopsug. Denna rapporthar som syfte att undersöka implikationerna av en sådan förändring. För att konkretisera syftet används tre frågeställningar: Vilka aktörer kan påverka, och påverkas av, en förändrad insamling av hushållsavfall, och vilken relation har de till varandra? Vad finns det för hot i aktörsnätverket och hur kan det utvecklas för att minska dem? Hur påverkas den yttre miljön av en installation av sopsug i en befintlig stadsdel? Dessa tre frågeställningar utreds och besvaras med hjälp av en litteraturstudie, en intervjustudie och en fallstudie. För att kartlägga vilka aktörer som finns i avfallsinsamlingens nätverk används en metod som kallas Customer Value Chain Analysis och för att bedöma miljöpåverkan används metoden Livscykelanalys. De viktiga aktörer som identifieras för den framtida avfallsinsamlingens nätverket är hushåll, fastighetsägare, Stockholm Vatten Avfall AB(SVAB), Envac AB, kommunfullmäktige, allmänheten och branschorganisationer. De hot som finns i nätverket är dels vad som händer om entreprenörers renhållningspersonal börjar ställa hårdare krav på arbetsmiljön så att den nuvarande insamlingen stoppas, men även hushållens förmåga att göra rätt eftersom att kvalitén på avfallsinsamlingen till stor del hänger på att de gör rätt. Dessutom ses det som ett hot att fastighetsägarnas värdeskapande inte är helt klarlagt och det är osäkert om kommunfullmäktige ser värdet i en förändrad avfalls-insamling. Dessa hot kan bemötas genom att arbeta för ett mer konsekvent kravställande på arbetsmiljö, undersöka möjligheten för SVAB att ansvara för informationen till hushåll, tydliggöra alternativen för fastighetsägare och sprida kunskap till kommunfullmäktige. För att bedöma miljöpåverkan av en sopsug i innerstaden görs en fallstudie av ett område på Södermalm i Stockholm som kallas Norra Sofia. En livscykelanalys görs för ett års avfallsinsamling för de 9500 personer som bor i området. Tre miljöpåverkanskategorier undersöks; försurning, global uppvärmning och övergödning. Resultatet av livscykelanalysen visar att sopsugens bidrag till försurning och övergödning är mindre än den manuellas. Beräkningen av de två miljöpåverkans-kategorierna har inneburit stora förenklingar och det finns en stor osäkerhet i de resultaten. Miljöpåverkanskategorin global uppvärmning däremot har en större säkerhet i beräkningarna och resultatet för denna visar att en sopsug leder till ungefär lika stora utsläpp av växthusgaser som den alternativa manuella insamlingen.

Hundreds of thousands of organizations have chosen to boost their competitive position by demonstrating compliance to the ISO 14001 Environmental Management System standard. In order for these standards to become credible policy options, they must ensure the capacity to build an industrial morality and to institutionalize responsibility. Relying on a series of in-depth interviews with environmental auditors, this dissertation contributes to a deeper empirical understanding of these regulatory instruments by, first, exploring how the adoption of an EMS promotes self-regulatory capacity and contributes toward effective environmental protection, and second, discussing the limitations of its accountability structure and the threats to the credibility of the standard. / This project highlights several misconceptions associated with the role of ISO 14001, and explains why both public and private sectors hold conflicting and inappropriate expectations regarding the certification process. According to the environmental auditors interviewed, the standard has helped thousands of committed organizations to effectively improve their self-regulatory capacity as well as their environmental performance. Yet, organizations with no intrinsic motivation can take advantage of the flexibility granted by the standard and the limitations of the conformity assessment process, to obtain an empty environmental certificate. ISO 14001 is a process standard that can help both 'environmental leaders and laggards', but that cannot differentiate organizations based on their level of environmental performance. Because of that, ISO 14001 is increasingly perceived as a socially unacceptable certification system. This project concludes that ISO 14001 is a double edge regulatory instrument that aims both to foster self-regulatory powers, and to act as a market signaling agent. The problem lies in the fact that these two facets of the standard are actually detrimental to each other, perpetuating a cycle that contributes to the discredit of the standard and of the auditing community. In the future, ISO 14001 needs to adjust its non-prescriptive nature and its accountability mechanism, to the character of the organizations seeking certification. In alternative, a new generation of certification programs is emerging, building upon the ISO 14001 standard with an extra layer of requirements, and with a more meaningful role for the environmental auditor.

Research is needed to ensure proper cotton N fertilization in various production practices without the detrimental effects of excess fertilization on yield and the environment. The objectives were i) to evaluate the effect of residual N on the uptake efficiency of cotton-applied N when following corn in rotation, ii) evaluate the potential for using leaf blade analysis and preset N thresholds to trigger foliar applications of N to cotton grown on clay soils and iii) evaluate the effect of preplant N on early root and shoot growth and N assimilation of cotton grown on a clay soil. Nitrogen rates of 0, 56 and 112 kg N ha^-1 as double labeled 5 atom% ¹⁵N NH₄NO₃^- were applied to cotton grown on Commerce silt loam (fine-silty, mixed, nonacid, thermic Aeric Fluvaquent) following previous corn N rates of 0, 168 and 280 kg N ha^-1. Total dry matter accumulation, total N assimilation and seedcotton yield on the upper third of the plant increased as corn- and cotton-applied N increased. Recovery of labeled N ranged from 40-53% in 1999 and 30-58% in 2000 and was highest following 0 or 168 kg N ha^-1 previous corn-applied N in both years. More plant N assimilation was soil-derived in both years following 280 kg corn-applied N ha^-1. Application of 112 kg N ha^-1 resulted in the most ¹⁵N assimilated but uptake efficiency was the lowest. Seedcotton yields of cotton grown on Sharkey clay (very fine, montmorillonitic, non-acid, thermic, Vertic Haplaquepts) using 44 or 67 kg soil-applied N ha^-1 along with foliar N as needed averaged 622 kg ha^-1 less than the recommended soil-applied rate of 134 kg N ha^-1 although N use efficiency was 34% higher. The lower yield occurred because of fewer bolls on the second and third fruiting positions of upper sympodial branches. Preplant N rate increased dry matter partitioning to shoots with potentially larger N reserves. This provided ample vegetative growth, more branching and production of fruiting sites, and provided adequate assimilate to meet this increased demand. Increased cotton yield appeared to be the result of N accumulation and not greater root growth.

Adsorption-desorption and transport behavior of pesticides are important processes that influence the amount retained by the soil and that which is susceptible to runoff or movement within the soil profile. Kinetic batch experiments were used to study the adsorption-desorption behavior of metolachlor (a non-ionic herbicide) and deltamethrin (a pyrethroid insectcide) in soils, and atrazine (a triazine) in sugarcane mulch residue. Miscible displacement experiments under steady flow conditions were carried out to examine the mobility of these pesticides in soils. Metolachlor adsorption and desorption by Sharkey clay soil(Very-fine, smectitic, thermic Chromic Epiaquerts) and Commerce silty loam soil (Fine-silty, mixed, superactive, nonacid, thermic Fluvaquentic Epiaquepts) soil were strongly kinetic. The Kd values of metolachlor adsorption for Sharkey were significantly higher than for Commerce. After six desorption steps, the average metolachlor desorbed was 30.5% and 43.9% for Sharkey and Commerce, respectively, and was dependent on the initial input concentration. Adsorption and desorption of atrazine by sugarcane mulch exhibited extensive kinetic behavior. Adsorption isotherms appeared linear for all reaction times. A linear multireaction model which accounted for reversible equilibrium and kinetic retention along with a consecutive irreversible reaction described both adsorption and desorption of atrazine retention results (r2=0.99). Deltamethrin retention by soils was strong, and positively related with cation-exchange capacity (CEC) and negatively related with soil pH. Deltamethrin recovery was dependent upon the initial input concentration, and did not exceed 10.2% of the total amount adsorbed for all the four soils (Sharkey clay, Mahan sand loam, Vacherie silty loam and Mhoon silt clay loam) representing a wide range of organic matter and clay contents. Extremely low mobility and thus strong retention for deltamethrin in the soil columns were observed. A new hysteresis coefficient based upon the difference in the area between adsorption and desorption isotherms was proposed. This coefficient was capable of quantifying hysteresis for both types of desorption isotherms: traditional desorption isotherms and time-dependent desorption isotherms. Results suggested that when an isotherm is measured based upon laboratory adsorption-desorption experiments or field measurements, equal reaction times should be maintained.

Smooth cordgrass (S. alterniflora) is a perennial grass that dominates the salt marsh in tidal wetlands along the Atlantic and Gulf Coast of North America and has been used for preventing soil erosion and restoring wetlands. Accessions collected from south Louisiana were studied to investigate flowering phenology, pollen viability, crossability, and seed production. S. alterniflora exhibited protogynous flowering where stigmas exserted 2 to 5 days from the floret prior to anthesis. Pollen shed primarily between 8:00 and 10:00 AM. Pollens were viable with average germination of 69% and stigma was receptive after exsertion. Pollen germinated in 15 minutes and pollen tubes reached micropyle in 55 to 75 minutes after contacting stigma. Protogyny could be used to produce controlled hybrid without emasculation and it could reduce tedious labor required for making crosses. S. alterniflora was cross-pollinated with 52% seed set for cross-pollination and 26% for self-pollination. Flowering started in early July and ended by the middle of October with a flowering peak between early September and early October. During the flowering peak, seed set, kernel weight, and seed viability were positively correlated to flowering date while unfilled and total seeds/panicle were negatively correlated with flowering date. Kernel weight, flowering date, seed weight/panicle, and panicle height were positively correlated with seed set. Plant flowering during the peak period might produce better seed set and seed weight. Field investigation showed an average seed set of 47% with range from 0 to 94% for S. alterniflora, which provided large opportunity for selection. Several lines with improved characteristics were selected and would be valuable for recurrent selection program with an objective of developing improved S. alterniflora populations. However, short term breeding objective should be focused on selection of plants from native collection that have high percentage of seed set, germination, and broad adaptability.

Uniola paniculata (sea oats) has been used extensively to build artificial dunes as well as stabilize existing dunes along the southern Atlantic and Gulf of Mexico coasts of United States. A breeding program could enhance coastal restoration by developing improved plants for beach restoration. Our goal was to initiate a successful breeding program for sea oats adapted to low dune profiles, with high seed yield and germination, and superior vegetative biomass essential for reducing coastal erosion. The specific objectives were to: 1) examine effect of storage environment on sea oats seed germination; 2) determine time necessary for sea oats seeds to germinate; 3) determine sea oats seed moisture content; 4) determine pathogen incidence during germination; 5) determine survival and performance of vegetative sea oats plants and sea oats seedlings at beach environments with shallow dune profiles; 6) develop efficient methods to identify saturation tolerant sea oats lines; 7) determine sea oats seed yield in natural and artificial environments and 8) identify fungal and bacterial pathogens of sea oats seed. Sea oats seed stored in hermetically sealed jars at room temperature had highest average germination and seed germination was highest 21 days after germination. Sea oats seed moisture content, ranged from 6 to 16 %, and was negatively correlated with germination. Small sea oats seedlings had highest mortality however, seedling cost significantly less than vegetative plants. Increasing seedling densities could reduce production costs and result in acceptable survival rates accompanied with genetic diversity. We found that small seedlings flooded continuously to 14 cm depth in greenhouse for 3 months could predict sea oats survival in saturated beach conditions after 6 months. In 2007, 2009, 2010, and 2011 we determined sea oats seed yield in natural and artificial environments. Consistent seed yields were not obtained for either environment; however, sea oats seed were produced in artificial production nurseries. Finally, to determine seed pathogens colonizing sea oats seed, bacteria and fungi were isolated from sea oats seed harvested in 2011 and identified using both morphological and molecular techniques. The dominant bacterial genera colonizing sea oats seed were Bacillus and Enterobacter; while the dominant fungal genera were Fusarium and Curvularia.

Nitrogen (N) is one of the most important and limiting nutrients in crop production. The best management practices for N fertilization is always challenging due to its dynamic system in the nature. Remote sensing has emerged as one of the most useful technologies in modern agriculture for non-invasive monitoring of plant N status. The objectives of this research were to 1) determine the effect of water background turbidity and depth on red and red-edge reflectance based prediction models for biomass and grain yield in rice, 2) evaluate agronomic parameters of different sugar cane varieties in response to variable levels of nitrogen supply, and 3) determine the effect of sugarcane varieties on the relationships between spectral reflectance and agronomic parameters. Rice experiments were variety (CL152 and CL261) x N trial established in Crowley, LA in 2011 and 2012. Sugarcane experiments were variety (L 99-226, L 01-283, and HoCP 96-540) x N trial established in St. Gabriel and Jeanerette, LA from 2010 through 2012. Spectral reflectance and agronomic parameters were collected each week for three consecutive weeks beginning two weeks before panicle differentiation in rice and for four consecutive weeks beginning three weeks after N fertilization in sugarcane. There was no significant effect of water background (turbid or clear) on the spectral reflectance at panicle differentiation, one week after panicle differentiation, and at 50 % heading (p <0.05). Water depth slightly influenced the reflectance at red waveband but this effect was not carried over when vegetation indices were computed. Use of red-edge based vegetation indices improved the estimation of biomass and grain yield in rice. The effect of variety on the accuracy of the yield prediction model varied depending on the transformation of reflectance within the red-edge and near infrared bands i.e., into normalized (NDVI) and simple ratio (SR) forms of vegetation indices. This result was associated with the behavior of near infrared wavebands on the geometrical structure of the plant canopy. There were no significant effects of variety on grain yield prediction models using derivative based red-edge indices. Our findings showed that red-edge based NDVI and SR are better predictors of rice grain yield than red-based NDVI and SR. Red-edge based NDVI or SR indices both have potential to predict rice grain yield and rice responsiveness to N fertilization. In sugarcane, the measured agronomic variables at early growth stage, i.e. biomass, tiller number, N content, height and FAI of three sugarcane varieties and their responses to N fertilizer were highly variable across year. The sugar yield response to N determined at harvest had stronger linear relationships with N response of biomass and N content at 4 to 5 weeks after N fertilization compared with N response of height and FAI. There were no differences in leaf spectral reflectance among varieties. In canopy level-spectral reflectance, wavebands at 450-500, 650-700, and 780-830 nm showed high correlation coefficient with agronomic parameters. The vegetation indices which have the potential for predicting biomass N uptake were red and red-edge based simple ratio and normalized difference vegetation index. Varietal effect on the models for estimating biomass and N uptake was significant only when red-based vegetation indices were used (p<0.05). Addition of plant height in the model substantially improved biomass and N uptake estimation while diminishing the effect of variety. Remote sensing technology can be a potential tool to estimate biomass and N uptake in rice and sugarcane. The delivered information from this technology is useful to improve mid-season N management.

Sustainability calls for policies that meet current societal needs without compromising the needs of future generations; thus, a dual relationship between human and natural resources is required. The main goal of the current research was to introduce up-to-date environmental techniques for sustainable natural resource utilization in semiarid and humid ecosystems in short and long term. To achieve this goal, two studies were implemented. First, sustainable land use management was evaluated in a newly reclaimed, semiarid region in the Bustan 3 area (341.27 km2), Egypt. To achieve sustainable management in this agro-ecosystem; detection of land cover change, assessment of the most sensitive areas to desertification, and evaluation of land capability for agricultural use were required. Using multi-temporal remotely-sensed data in the Bustan 3, the results indicated that this area had been drastically changed from 100% barren desert land to 79% agricultural land, due to successful land reclamation efforts in the 1990s. Although 70% of this area had a good capability for agricultural production, ¡­89% of the Bustan 3 area was critically sensitive to desertification. By applying suitable land management scenarios, the land capability for agricultural use could be increased. Second, a natural resource conservation program was examined by studying the effects of compost/mulch, as a best management practice, for soil erosion control on highway roadsides in Louisiana, USA (a humid region). Louisiana is plagued by widespread impairments to surface water quality. Total suspended solids (TSS) and associated turbidity in runoff water are considered the most problematic nonpoint source pollutant of Louisiana surface waters. At the plot scale, the effects of compost/mulch on soil and water resources were evaluated. Research results showed that the use of compost/mulch without tillage incorporation successfully conserved the topsoil on the roadsides, increased soil moisture retention, moderated soil temperature, and reduced the TSS, soil loss, runoff, and water flow rate. Tillage incorporation is not recommended since it decreased the compost/mulch effectiveness in reducing runoff and sediment losses. While the two studied areas, in semiarid and humid regions, were disparate in their characteristics, sustainable natural resource management was successfully achieved by using appropriate management practices in each case.