Spatial and temporal heterogeneity of water and nutrient pools is closely associated with the existence of different plant communities in hydrologically-controlled ecosystems such as the Everglades. These various communities differ in their flooding and fire tolerances as well as nutrient requirements. Upland plant communities are of particular ecological significance since they have high biodiversity and provide habitat to terrestrial fauna, yet comprise less than 10 % of the total area. Restoration and maintenance of such communities requires an understanding of their water and nutrient requirements. Chapter 2 compares water source utilization in hammocks and pine rocklands on the Miami Rock Ridge using stable isotopes of water. Hammocks do not flood, while adjacent pinelands may flood between 2-3 months. In the wet season, hammocks were found to use phosphorus (P) rich soilwater, a local pool of water and nutrients while pineland plants primarily relied upon groundwater, the regional pool. Access to a rich pool of P in the oligotrophic Everglades was associated with higher community-level foliar P concentration in hammocks. However in the dry season, hammocks utilized groundwater, which suggests sensitivity to extended droughts. Chapter 3 compares the hammock (upland or head) and swamp forests (lowland or tail) on tree islands in the Shark River Slough. Uplands were associated with P-rich soilwater uptake in the wet season, with regional water uptake in the dry season. Accordingly, tree island heads are rich in foliar P and thereby P-hotspots in the Everglades. Foliar nutrient concentrations can thus indicate limiting nutrient availability in the Everglades. Chapter 4 looks at how leaf phenology patterns are tied to water and nutrient pools. Leaf fall in ridge hammocks is associated with high foliar carbon isotope values over the dry season, which is not the case for tree island hammocks. However, in some species, high levels of foliar nitrogen are also associated with high foliar C13 values indicating stomatal limitation of photosynthesis. Growing season for most hammock species is the wet season coinciding with high availability of P, as reflected in high foliar P in this season. Linking water sources to foliar nutrients elucidates roles of water and nutrient pools in leading to different plant communities within an ecosystem.

The aim of this study was to understand the contribution of Linear Alkylbenzene Sulfonates (LAS) to the decline of Mediterranean coastal forest exposed to marine aerosols. LAS are a group of synthetic anionic surfactants widely used in the composition of household or industrial detergents and agrochemicals. This study was part of a large project (RISICO) aiming the assessment of the environmental impact of the LAS at multiple levels: biodegradation in the coastal waters, sorption – desorption processes in the sediments, toxicity to the aquatic life and toxicity to the coastal forest (by aerosolisation of the sea water). Previous studies pointed out this group of surfactants as the main cause of the coastal forest decline. However, the quantification of this surfactant in the environmental samples (mainly sea water and foliar deposition) was done using non-specific analytical methods as methylene blue active substances (MBAS), leading to overestimation of the environmental concentrations of LAS. The work hypothesis was that at actual environmental concentrations, the LAS does not play a key role in the foliar uptake of the sea salt deposited on the coastal vegetation by the marine aerosols, therefore the LAS may not be the main cause of the coastal forest decline. The research involved both greenhouse experiments and field measurements. The experimental work was conducted on young Mediterranean trees (Laurus nobilis L., Quercus ilex L. and Pinus halepensis P. Mill.) and investigated the synergistic toxic effects of exposure to simulated marine aerosol contaminated with surfactants. An array of endpoints was used including photosynthetic activity, relative water content, foliar deposition and uptake of salt and LAS, and pigments analysis. The results of those experiments revealed that LAS itself did not have phytotoxic effects. Nevertheless, the surfactant was shown to enhance the foliar uptake of the salt in the tested species, especially in Pinus halepensis, confirming the conclusions of previous studies regarding the sensitivity of this species to polluted marine aerosols. The field work was conducted in San Rossore National Park (Italy) and Porquerolles Island (France) and was focused on evaluating the health status of the Mediterranean forest (Quercus ilex L., Pinus halepensis Mill. and Pinus pinaster Aiton.) and also on quantification of LAS in coastal aerosols using highly specific analytical methods, like the mass spectrometry (MS). The frequencies and extent of injuries in the coastal trees were found to be correlated to the salt but not with the LAS content of the leaves. The concentrations of LAS in the Pinus and Quercus leaves were comparable in the two studied sites but the concentrations of salt were extremely high in San Rossore, suggesting that other factors may determine the excessive salt foliar uptake. The parallel MS and MBAS carried out in the same set of aerosol samples revealed that MBAS measurements were not relevant for LAS concentrations in the marine aerosols. Projecting the experimental results to the real LAS and salt exposure of the coastal forest, we concluded that LAS may play a marginal role in coastal vegetation decline.

Atlanta is one of the largest metropolitan areas in the southeastern United States and is the only area in the region currently listed in “serious” 1-hour ozone nonattainment. Despite its exceedance history, impacts on Atlanta’s urban forests have not been the focus of any major studies. The purpose of this study was to examine air pollution damage to vegetation using a foliar-injury survey on Stone Mountain. The objectives of this project included 1) establishing that pollution transport from Atlanta to Stone Mountain occurs, 2) determining the magnitude of ozone concentrations near Stone Mountain and 3) assessing sensitive plant species on Stone Mountain for foliar injury. Results from this study confirm that Stone Mountain is located downwind from Atlanta. Ozone concentrations were sufficiently high to damage vegetation and these consistently peaked in July. Foliar injury was present on understory species on Stone Mountain, but was not observed on loblolly pine species.

Knowledge of optimum concentrations and ratios of major nutrients in tree foliage is required to assess the nutrient status of the boreal forest. This thesis aimed at determining foliar nutritional standards for white spruce (Picea glauca (Moench) Voss), black spruce (Picea mariana Mill. B.S.P.) and jack pine (Pinus banksiana Lamb.) and to assess the nutrient status of forest stands across Canada for all major nutrients (N, P, K, Ca, Mg and Mn) using critical values (CVA) and compositional nutrient diagnosis (CND). Trees were sampled at three locations in Ontario and Quebec to cover a gradient of soil fertility levels. A boundary line approach was used in combination with quadratic regression models to assess the relationship between growth and foliar nutrient concentrations or CND scores when free of the effects of interacting environmental factors. (Abstract shortened by UMI.)

The nutrient status of three Norway spruce (Picea abies L. Karst.) plantations in southwestern Quebec were studied through foliar analysis. At all locations low N and K and marginal Mg foliar concentrations were identified. / Diagnostic fertilization resulted in significantly improved foliar K, N, Ca/K molar ratio and in some cases Mg. The foliage of the treated trees has an improved dark green colour as compared with the controls. From this research it is evident that nutrient deficiencies of N, and K in particular, are showing up in spruce stands in the areas where atmospheric pollution is relatively severe. The use of foliar nutrient concentrations along with evaluation of visual decline symptoms give the best results in assessment of the trees' current nutrient status. Proper diagnostic fertilization, using KNO$ sb3$ and (K,Mg)SO$ sb4$, helped to correct the nutrient disturbances on the calcareous soils of the region, impoverished by former agricultural use. In these soils the balance of Ca with K and Mg is crucial for their proper uptake. The base cations addition enlarged the available P pool, as a result of the improved organic matter decomposition. (Abstract shortened by UMI.)

Two studies were conducted to assess physiological responses of declining sugar maple (Acer saccharum Marsh.) in southern Quebec to wet acidic precipitation and increased soil fertility. Leaves of sugar maple were relatively acidic, had low external neutralization capacity (ENC = 5.1 $ mu$equiv. H$ sp{+} rm g sp{-1}$) and buffering capacity index (BCI = 103 $ mu$equiv. H$ sp{+} rm g sp{-1}$), and higher ENC/BCI compared to three other tree species. Deciduous species showed a higher BCI and a lower ENC in August. Our results suggest that sugar maple may be relatively sensitive to wet acidic deposition and that leaf buffering capacity is related to photosynthesis potential and seasonal change in foliar Ca concentration. Foliar analyses revealed that fertilization with a mixture of K, Ca, and Mg had significant effects on leaf concentrations of K, free amino acids (FAA) and the ratios of N to K, and FAA to N after two growing seasons. Our results suggest that base cation fertilization improved the N and K status of sugar maple and that leaf carbon partitioning appeared to be more dynamic in fertilized trees.

Eight fertilization treatments were applied in May 1987 to two sugar maple stands. This was followed by soil and foliar sampling and decline evaluation in mid-summer 1987 and foliar sampling and decline evaluation in mid-summer 1988. / Trees selected for sampling purposes on average showed evidence of light to moderate decline. Foliar nutrient status was found to be poor at both sites, with Ca, Mg, K and P at or very near to deficiency levels although foliar molar ratios for Ca/K, Ca/Mg and Ca/Al were well within their respective critical ranges. / Fertilization had significant effects on several elemental concentrations of the soil and foliage at the Entrelacs sites. Effects in general showed an increase in base cation concentrations when those elements were supplied in high enough quantities in the fertilizers. Fertilization had no significant effect on decline levels. / Positive correlations were obtained between soil B horizon levels and foliar Ca, Mg and K and between soil FH horizon levels and foliar K and Al.

Tall ironweed (Vernonia altissima) and Canada thistle (Cirsium arvense) control in cool season grass pastures was evaluated in 2007 and 2008. Tall ironweed was evaluated in Fayette and Boone Counties, KY and Canada thistle was evaluated at Spindletop Research Farm. Herbicides applied selectively with a rope-wick were compared to a broadcast foliar spray. Treatments were a broadcast treatment, of aminopyralid + 2, 4-D and six rope-wick treatments: aminopyralid at three concentrations, glyphosate, triclopyr and clopyralid at one concentration each. The Boone County location had five broadcast foliar treatments: aminopyralid at three rates, triclopyr + fluroxpyr, and 2,4-D + triclopyr. The Canada thistle study consisted of the same six rope-wick treatments as the Fayette County tall ironweed study. A broadcast treatment of aminopyralid at 70 g a.e./ha was included in 2008. Studies were evaluated 1, 2, 3, 4, 8 and 52 weeks after treatment. Aminopyralid plus 2,4-D provided 86% control of tall ironweed 52 WAT. Aminopyralid at 20% v/v controlled 65% of tall ironweed. Canada thistle control 52 WAT ranged from 0 to 25% control for the six ropewick treatments.

Optimum nutritional levels for most commercial hardwoods of eastern Canada are unknown. This thesis dealt with the development of a method to determine nutritional standards using within site variation in tree growth and foliar chemistry. To this end, sugar maple (n = 87) and red maple (n = 39) trees were sampled in summer 2001 at the Station de biologie des Laurentides. Leaves were sampled for nutrients (N, P, K, Ca, Mg and Mn) and tree stems were measured for determination of basal area growth (BAG). Similar measurements for trees sampled annually during 1995--2001 were also used to measure the effect of annual variation on nutritional standards. A boundary line approach was used to assess tree growth response to nutrition using nutrient concentrations and Compositional Nutrient Diagnosis (CND) scores as predicting variables. A Basal Area Growth Index (BAGI) was computed using the live crown ratio to correct for the effect of stand density on BAG. An iterative and unbiased protocol was also developed to eliminate outliers. Optimum, critical and optimal range levels were derived from quadratic models significant at P < 0.15.

No description available.