The Christmas tree and greenery trade is a multi-million dollar industry in Atlantic Canada. Christmas trees grown in Nova Scotia are shipped internationally especially, to the United States. This thesis was set out to answer the over-arching hypothesis: pre- and post- harvest needle nutrient content influences post-harvest needle retention. Through a series of experiments it was shown that the pre-harvest needle P, Ca, Mg, Mn, Zn and B contents do not appear to be directly linked to post-harvest needle retention. Alternatively, the pre-harvest needle N, K, Cu and Fe contents significantly, but negatively influenced post-harvest needle retention. By maintaining needle N, K, Cu and Fe concentrations below 1.5 %, 0.55 %, 3.7 ppm and 35 ppm, respectively may extend needle retention in balsam fir. Xylem-fed nutrients negatively influenced needle retention. As well, foliar applications of calcium and zinc citrate did not promote needle retention at the concentrations used.

In June 2005, fieldwork was conducted during the spring snowmelt period at Cape Bounty, Melville Island, Nunavut to examine the relationships between snow accumulation, runoff, and nutrient fluxes in two High Arctic watersheds. The snowcover was quantified by means of eleven depth and three density measurements at 42 survey transects (100 m) distributed throughout the West and East watersheds. River discharge was monitored at the watershed outlets, where water samples were collected four times daily during the first ten days of melt and twice daily once flow receded. Water samples were also collected from headwater and tributary sites in the two watersheds, and samples were analyzed for DOC, DON and DIN (NH4+ and NO3-). An objective terrain classification weighted equally on slope, aspect and land surface curvature was applied to the two watersheds using an ISODATA unsupervised classification scheme to determine watershed SWE. The terrain model confirmed that topography likely explains greater SWE in the West watershed, and provides a method for reproducible estimates of watershed SWE in future years. However, improved methods for estimating SWE in channels and deep snowbanks are required to ensure accurate assessments of watershed SWE. The seasonal trends in DOC, DON, and DIN concentrations and specific fluxes are reported for both watersheds. The export of DON and DIN was strongly correlated with DOC in the West watershed, indicating that the flushing of terrestrial nutrients from surficial soils by snowmelt runoff governs nutrient export. Despite less watershed SWE (51%), the East watershed exported greater specific fluxes of DOC (33%) and DON (43%) during the melt season. This suggests that the East watershed had greater connectivity with OM sources early in the melt season. Furthermore, low DOC:DON ratios (< 15) in the East River indicate that a larger portion of DOM was likely derived from algal or microbial sources in the East watershed relative to the West watershed. The export of DIN was similar in the two watersheds, and results suggest that DIN export was likely controlled by watershed vegetation coverage and runoff volumes during snowmelt. / Thesis (Master, Geography) -- Queen's University, 2008-07-08 00:31:46.107

Hybrid physiological models are being increasingly used to assess productivity, carbon sequestration, water and nutrient use and environmental impacts of management decisions. Users include forest managers, politicians, environmental agencies and scientists. However a wider use of these models has been prevented as a result of an incomplete understanding of the mechanisms regulating carbon allocation, nutrient availability in soils and nutrient uptake by trees. On-going innovation in clonal forestry, genetic improvement and vegetation management techniques is also poorly represented in hybrid models. This thesis examines means to represent nutrition and genotype-nutrition interactions in productivity physiological hybrid models. Nutrient limitations and growth differences between genotypes were hypothesized to operate through key physiological processes: photosynthesis, carbon allocation and nutrient internal cycling. In order to accomplish the aims of the study both greenhouse and field experimentation were carried out. In a first experiment, responses of photosynthesis (A) to intercellular CO₂ concentration (Ci) were measured in a fast- and a slow-growing clone of Pinus radiata D. Don cultivated in a greenhouse in a factorial combination of nitrogen and phosphorus supply, and analyzed using the biochemical model of leaf photosynthesis described by Farquhar et al. (1980). There were significant positive linear relationships between the parameters, Vcmax, Jmax, Tp and both foliar nitrogen (Na) and phosphorus (Pa) concentration on an area basis. The study showed that the effects of nitrogen and phosphorus supply on photosynthesis were statistically independent and that the photosynthetic behaviour of the two clones was equivalent. In a similar study, gas exchange and chlorophyll fluorescence were simultaneously measured to determine internal transfer conductance (gm) based on the "constant J method". Transfer conductance may pose significant limitations to photosynthesis which may be differentially affected by nutrition and genotype in Pinus radiata. Values of gm were similar to those of stomatal conductance (gs) and their ratio (gm / gs) was not influenced by nutrient supply or clone being on average (±1 SE) 1.22 ±0.04. Relative mesophyll limitations (LM, 16%) to photosynthesis were marginally greater than those imposed by stomata (LS, 13%), and together smaller than the relative limitations posed to photosynthesis by biochemical processes (LB, 71%). The CO₂ concentration in the intercellular air spaces (Ci) was (±1 SE) 53 ±3 µmol mol-1 lower than in the atmosphere (Ca) while CO₂ concentration in the chloroplasts (Cc) was (±1 SE) 48 ±2 µmol mol-1 less than Ci. Values of LS, LM and LB and CO₂ diffusion gradients posed by gs (Ca-Ci) and gm (Ci-Cc) did not change with nutrient supply or clone. In a third experiment, one-year old Pinus radiata cuttings from four genotypes were cultivated in silica sand with a factorial combination of nitrogen (N0=1.43 and N1=7.14 mM) and phosphorus (P0=0.084 and P1=0.420 mM) supply for 24 months. N supply was enriched with ¹⁵N to 2.5⁰/₀₀ (labelled N) during the first year, then plants transferred to clean sand and cultivated for another year with ¹⁵N at levels close to natural abundance (0.3664899 atom percent ¹⁵N, δ¹⁵N 0.5115 ⁰/₀₀) provided by the source of N in nutrient solution applied during the second year. Recovery of labelled and unlabelled N was used to estimate N remobilization. N remobilization scaled with plant growth, N content and N and P supply. In relative terms, 65% of all stored N was remobilized in the high-nutrient supply regime compared to 42-48% at lower N and P addition rates. Most N remobilization occurred during spring-summer (77%), coincidently with the largest proportion of needle development (80%), indicating that N remobilization was driven by sink-strength. Foliage was by far the main source for internal cycling while roots were the main sink (40%). Clones exhibited differences in N remobilization capacity, but these differences were completely explained by the size of the N pool before remobilization took place, indicating that N remobilization performance was similar among clones. In a fourth study, four clones were cultivated in silica sand with a factorial combination of nitrogen and phosphorus supply for ten months, and patterns of carbon allocation examined using a carbon balance approach. Gross-primary productivity (GPP) scaled mainly with nitrogen but also with phosphorus supply. The fraction of GPP (GPP = ANPP + APR + TBCA) allocated to above-ground components (ANPP) increased with N and P supply at the expense of total-below ground C allocation (TBCA) with no apparent effect on the fraction of GPP partitioned to above-ground plant respiration (APR). Carbon use efficiency (NPP:GPP) scaled with nutrient supply, being 0.42 in the low-nutrient supply regime compared to 0.51 in the high-nutrient supply regime, suggesting that in poor fertility environments a larger proportion of the C budget is respired compared to the net productivity. Fast-growing clones allocated about 2-4% more carbon to above-ground components (ANPP) at the expense of carbon allocated below-ground (TBCA) with no effect on carbon respired above-ground (APR), indicating that faster-growing genotypes allocate more carbon to leaf area which may compound and increase overall GPP over time. The field component of this thesis was conducted in a subset of locations where ENSIS (formerly New Zealand Forest Research Institute) had established trials to test the influence of species, soil disturbance and plant nutrition on sustainability indicators. Plots were small in size (3 m × 3 m) with trees spaced at 0.5 m × 0.5 m (40 000 trees ha-1) with nine measurement trees surrounded by a two-row buffer. All sites were planted in winter 2001 and harvested in spring 2005. The aim of this pilot study was to examine patterns of carbon allocation during the fourth year after planting in control and fertilized mini-plots of Pinus radiata in five sites with contrasting climate and soil conditions in the South Island of New Zealand. The study showed that the fraction of gross-primary productivity allocated belowground increased as the soil C:N ratio increased. However, these results should be interpreted with caution due to the unusual nature of the trial and the reduced number of sites studied. Two existing physiological models were selected for the discussion in this thesis (3-PG, Landsberg and Waring 1997; canopy net carbon exchange model, Whitehead et al. 2002). Potential improvements for the nutritional component of 3-PG comprise: accounting for reductions in carbon use efficiency (NPP:GPP) in poor-fertility environments, adding a preliminary fertility modifier (FN, 0-1) driven by soil C : N ratio and soil N, adding a preliminary relationship between carbon allocation to roots and the soil C : N ratio and representing faster-growing genotypes by increasing their leaf area but not their photosynthetic performance. The canopy net carbon exchange model (NCE) combines the coupled model of leaf photosynthesis - stomatal conductance described by Leuning (1995) with canopy structure and a water balance model to scale carbon assimilation from leaves to canopies. Potential improvements to account for nutrient deficiencies in the leaf model by Leuning (1995), comprise using nutrient ratios to discriminate nitrogen (Na/Pa < 23 mol mol-1) from phosphorus deficiencies (Na/Pa > 23 mol mol-1), adding relationships between photosynthetic model parameters Vcmax and Jmax to Pa, and correcting the estimation of photosynthetic parameters Vcmax and Jmax by accounting for transfer conductance (gm). The canopy net carbon exchange model may be also modified to account for carbon-use efficiency, carbon allocation to roots and genotype in a similar form to that proposed for 3-PG. The results previously outlined provide a preliminary framework to represent tree and soil nutrition in physiological hybrid productivity models.

No description available.

Agricultural runoff is a major non-point source of phosphorus (P) and nitrogen (N) in aquatic environments and often contributes to coastal eutrophication. Chemical extraction techniques that measure P and N in runoff and sediments have provided little information on biologically available P and N, particularly when soils/sediments move from an agricultural setting to freshwater, estuarine and marine systems. The aims of this thesis were to a) develop algal bioassay techniques for assessing bioavailability of P in marine and freshwater sediments, b) apply algal bioassays to determine the role of suspended sediments as P and N sources c) examine how sediment type and sediment load affect P bioavailability and identify the chemical analysis of soil P that best reflects bioavailable P, and d) determine nutrient bioavailability of agricultural soil runoff in estuarine and coastal marine ecosystems. An accurate and repeatable sediment bioassay was developed using non-axenic uni-algal cultures of the euryhaline diatom Skeletonema costatum and freshwater chlorophyte Selenastrum capricornutum. Bioassays were conducted in 250 mL Erlenmeyer flasks, with 100 mg L-1 of simulated sediment and 100 mL of modified growth media, which were continuously shaken. Suspended sediments were simulated from 7 major soil types of the Maroochy River catchment in Australia, a coastal catchment influenced by agriculture. Simulated sediments were used as the sole P source in replicate batch 7-14 d bioassays in which changes in in vivo Chl a fluorescence were measured. Maximum algal biomass in bioassays was significantly correlated to total sediment P content of the added sediment in marine and freshwater. Bioassay methodology was adapted to assess N as well as P bioavailability in simulated suspended sediments using Skeletonema costatum. S. costatum biomass was significantly influenced by sediment type and correlated with the Total P content of the sediment. Conversely, S. costatum response did not correlate to total nitrogen (TN), ammonium (NH4+), nitrate (NO3-) and easily mineralisable N content of the sediment. Sediment type did significantly influence response, suggesting that sorption/desorption properties of the sediment influenced N bioavailability. Suspended sediments appear to be a significant source of bioavailable P as S. costatum biomass was enhanced by their addition. Conversely, the lack of stimulation by sediments when used as a N source implies that suspended sediments are not an immediate source of bioavailable N, although they do contribute to the sediment nutrient pool once deposited. The influence of sediment type and sediment load on phosphorus (P) bioavailability was compared using Skeletonema costatum bioassays. The amount of sediment and associated P load influenced the maximum algal biomass reached, with low sediment loads (&lt 100 mg L-1) capable of stimulating high algal biomass. Maximum algal biomass correlated with sediment iron-oxide extractable inorganic P (FeO-P) and inorganic P (Pi) extracted by sodium bicarbonate for all sediment types. Total P (TP) did not discriminate at low TP concentrations and organic P (Po) extracted by sodium bicarbonate only correlated with algal biomass when bioavailable P was low. Thus FeO-P and Pi are the most representative analyses of bioavailable P. FeO-P can also be used to accurately measure rate of sediment P desorption, which significantly influences algal growth rate. Nutrient bioavailability of agricultural soil runoff was investigated in the Maroochy River catchment in southeast Queensland Australia, a coastal catchment influenced by agriculture. Suspended sediments, river and estuarine sediments and deposited sediment in the near-shore coastal zone were collected and analysed for nutrient bioavailability using chemical analyses and S. costatum bioassays. Suspended sediments in the Maroochy River, which consisted of silt and clay sized particles, had elevated FeO-P and TP concentrations comparable to fertilised soil. Similarly the deposited sediment sampled offshore to the river mouth had elevated total P, FeO-P and total N concentrations which were much greater than the underlying marine sediment. The deposited offshore sediment contained mainly silt sized particles and appeared to be terrigenous in origin as it was more similar in composition (TP, FeO-P, TN, total carbon, total aluminium, total iron, total silica) to estuarine suspended sediments and terrestrial soils, than the underlying marine sediment. This study demonstrated that fine silt sized particles, rich in bioavailable P and N, are being transported and deposited offshore during erosion events. These findings highlight the importance of effective land management and erosion control measures that reduce the suspended sediment load. Although agricultural practices are continually improving to reduce soil erosion, practices need to encompass a broader approach that emphasizes the link between land and sea. Effective management must consider agricultural productivity as well as the environmental impact or ‘algal bloom potential’ that a soil may have when eroded into a waterway. Soils high in bioavailable nutrients must be targeted and managed effectively, particularly in areas prone to erosion.

Coastal ecosystems continue to come under increasing pressure from human activities and the input of anthropogenic substances. This is being realised in a number of areas where eutrophic conditions begin to dominate and phenomena such as toxic algal blooms increase in frequency. Amidst this situation there is a growing need to understand how ecosystem components such as benthic fauna might respond to these conditions and how we might better use some of these components as indicators of ecosystem perturbation. In this context the current study examines the distribution and abundance of sediment meiofauna in seagrass beds at two different locations in Moreton Bay estuary. This ecosystem presently receives significant anthropogenic inputs from the Brisbane River and other sources draining the greater Brisbane catchment and adjoining areas. The main aims of the study were to characterise the distribution and abundance of meiofauna in these sediments and to also examine some of the main factors influencing these features. Also, it was intended that on examination be made of the influence that blooms of the cyanobacterium Lyngbya majuscula might have on meiofauna abundance and distribution in these areas. Blooms of this alga are an increasing feature of the Moreton Bay estuary and potentially represent a strong influence on a range of habitats and organisms within the ecosystem. In considering the physico-chemical aspects influencing meiofauna, sediment grain size and nutrient levels were shown to have some effect on distribution and abundance although this varied between species and location. Further, the grain size of the sediment and the total organic carbon did not change significantly between bloom and non-bloom periods and but total nitrogen and C/N ratio did show a change. In regard to the observed effects of the L. majuscula blooms, a negative impact was observed on copepod and nematode abundance and distribution. In both cases their abundance was considerably smaller during the bloom period. Notably, polychaetes showed no effect from the bloom?s occurrence. The results also indicate that during the bloom the meiofauna were distributing shallower in the sediment, probably due to the hypoxic conditions that the bloom may have created. Moreover, the impact of the bloom was more pronounced in the smaller size classes for the meiofauna and suggests that these classes are more sensitive to the conditions generated by the deposited bloom material. Under Multiple Regression Analysis nematodes and polychaetes were positively correlated with sediment nitrogen concentration, while copepods were not. Also, during the bloom the nitrogen concentration in the sediment increased but the abundance of nematodes showed an opposite trend. The general negative effect of the bloom on the total fauna might be the responsible for this result. An attempt was also made to assess whether the nematode:copepod ratio (Ne:Co) could be used in this ecosystem as an indicator of pollutant input or habitat disturbance by the algal bloom. This ratio has been used elsewhere with some success. Results from this study indicated that this ratio has only limited value as an indicator in the study situation and that the concomitant influence of sediment grain size and nutrient levels lead to a potentially misleading interpretation of the results that the ratio provides. The interactions between meiofauna, the prevailing physico-chemical and biological characteristics of the sediments in Moreton Bay are clearly very complex. The influence of phenomena such as the Lyngbya blooms adds to this complexity but, in the current study, this was seen to clearly have an effect on both animal abundance and their distribution. In this regard, the present study has identified the key areas of influence from the algal blooms and has also highlighted the need to further research these important animal groups so that we may better understand how the benthos, and thus the wider ecosystem, might cope with pollutants and anthropogenic disturbances.

Diss. (sammanfattning) Uppsala : Univ., 2004. / Härtill 6 uppsatser.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains ix, 115 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 78-80).

Understanding relationships between biodiversity and ecosystem function is a critical challenge, particularly in freshwater ecosystems where species losses are occurring at unprecedented rates. There is a particular need to examine these relationships in natural settings at large spatial scales. Ongoing, disease-driven amphibian declines may influence the structure and function of stream ecosystems, but little is known of the potential roles of stream-dwelling tadpoles in consumer-resource dynamics, ecosystem functions such as decomposition, and ecosystem-level biogeochemical cycling. Tadpoles in tropical streams likely regulate flows and ratios of nitrogen (N), phosphorus (P), and carbon (C), influencing ecosystems by altering nutrient supplies to other animals and their food resources. I used ecological stoichiometry as a framework to assess how the sudden loss of consumer biodiversity in neotropical headwater streams affected ecosystem function. I quantified N and P excretion and C:N:P ratios of tadpoles, macroinvertebrates, and food resources in healthy sites (pre-decline) and sites where disease-driven amphibian declines had occurred (post-decline). I tested the hypothesis of consumer homeostasis (i.e., that organisms maintain consistent body nutrient ratios by altering excretion chemistry) over a range of taxa and size classes. I also used mesocosms in a natural stream setting to quantify the effects of grazing tadpoles, shredding macroinvertebrates and a combination of the two on leaf decomposition and associated microbial activity. Finally, I examined macroinvertebrate community structure and quantified biomass and nutrient storage in tadpoles, macroinvertebrates, and basal resources in pre-decline and post-decline sites. I also measured excretion rates, volumetric excretion, and nutrient turnover for both tadpoles and macroinvertebrates. Patterns of consumer-resource stoichiometry varied with the presence or absence of tadpoles. There were higher concentrations of C, N, and P in basal resources in pre-decline sites compared to post-decline sites, but little variation in elemental ratios among sites. Elemental composition and molar ratios in grazers and shredders varied, with pronounced differences in %N for gatherers and filterers across sites. Macroinvertebrate grazer elemental composition was higher for all elements and had lower C:N, N:P, and C:P molar ratios in pre-decline sites compare to grazers in post-decline sites, while shredders showed the opposite pattern. There were differences in both taxon-specific allometric and stoichiometric relationships in tadpoles and macroinvertebrates between pre- and post-decline sites. Body P content was a good predictor of tadpole P excretion and tadpoles in pre-decline sites excreted more P per unit body P than those in post decline sites. Individuals deviated from strict homeostasis, and the degree of deviation varied among taxa. Tadpoles also affected leaf decomposition by influencing microbial communities and altering shredding macroinvertebrate feeding. Higher respiration rates of leaf discs in chambers with tadpoles suggested that tadpoles enhanced microbial activity by excreting nutrients through feeding and excretion. Shredders alone had little effect on respiration rates, indicating that tadpoles play an important and unique role in enhancing microbial activity and litter decomposition. Leaf area loss was greatest when tadpoles and macroinvertebrates were together, indicating facilitation. Macroinvertebrates are important nutrient recyclers in neotropical headwater streams, but their role is greatly decreased in the absence of larval amphibians. I measured ~80% lower standing stocks and storage of C, N, and P in basal resources in post-decline compared to pre-decline sites. Storage of C, N, and P in both tadpoles and macroinvertebrates also decreased in post-decline sites. I also observed 98% decreases in tadpole nutrient excretion and egestion rates, and an additional decrease in macroinvertebrate excretion rates (~80%) for both N and P in post-decline versus pre-decline sites. These decreases led to >8,000% increase in the distance that it took tadpoles to turn over the ambient N pools in post-decline sites, and a 130% increase for macroinvertebrates. Similar patterns were evident for P turnover, with turnover distance increasing by 6,000% and 400% in post-decline sites for tadpoles and macroinvertebrates, respectively. My results indicate that N and P excretion by both tadpoles and macroinvertebrates constitute significant nutrient fluxes in these headwater streams. Both tadpole and macroinvertebrate communities were excreting nutrients at similar rates in pre-decline sites, suggesting that they were playing equally significant roles in their contribution to ecosystem demand. My results demonstrate that tadpoles are important consumers in Neotropical headwater streams and their loss significantly alters stream food webs and ecosystem functions.

Previously, we have demonstrated that nicotinamide (NAm), a neuroprotective soluble B-group vitamin, improves recovery of function following traumatic brain injury (TBI). However, no prior studies have examined whether NAm is beneficial following continuous infusions over seven days post-TBI. The purpose of this study was to investigate the preclinical efficacy of NAm treatment as it might be delivered clinically; over several days by slow infusion. Rats were prepared with either unilateral controlled cortical impact (CCI) injuries over the somatosensory cortex (SMC) or sham procedures and divided into three groups: CCI-NAm, CCI-vehicle, and sham. Thirty minutes following CCI, Alzet osmotic mini-pumps were implanted subcutaneously. NAm was delivered at a rate of 50 mg/kg/day for seven days immediately post-CCI. On day seven following injury, the pumps were removed and blood draws were collected for serum NAm and nicotinamide adenine dinucleotide (NAD+) analyses. Starting on day two post-CCI, animals were tested on a battery of sensorimotor tests (bilateral tactile adhesive removal, locomotor placing, and limb-use asymmetry). Statistical analyses of the tactile removal and locomotor placing data revealed that continuous administration of NAm significantly reduced the initial magnitude of the injury deficit and improved overall recovery compared to the vehicle-treated animals. NAm treatment also significantly decreased limb-use asymmetry compared to vehicle-treated animals. Continuous infusion of NAm resulted in a significant serum elevation in NAm, but not NAD+, as well as significantly attenuated cortex tissue loss than un-treated animals. The NAm-treated group also had the lowest number of glial fibrillary acidic protein (GFAP) positive cells. No detrimental effects were seen following continuous infusion. The present results suggest that NAm delivered via a clinically relevant therapeutic regimen may truncate behavioral damage following TBI. Thus our results offer strong support for translation into the clinical population.