The Bromeliaceae is one of the largest and most ecologically diverse angiosperm families in the Neotropics. In recent years, this family has begun to emerge as a model system for the study of plant evolutionary ecology and physiology, and major advances have been made in understanding the factors involved in episodes of rapid diversification and adaptive radiation in specific bromeliad lineages. However, despite a long tradition of ecophysiological research on the Bromeliaceae, an integrative, evolutionarily-contextualised synthesis of the links between anatomical) physiological, and ecological aspects of bromeliad biology has hitherto been lacking. The overarching aim of this research project was therefore to use new quantitative data representing a wide range of bromeliad taxonomic and functional groups to elucidate how variation in leaf traits connected by structure-function relationships influences ecological differentiation among bromeliad taxa. Special emphasis was placed on hydraulic and water relations traits because of fast-paced contemporary developments in these fields. The methodologies employed included an assessment of the diversity of bromeliad hydrological habitat occupancy, quantification of key anatomical and physiological traits and their correlations, investigation of the links between vascular and extra-xylary anatomy and hydraulic efficiency and vulnerability, quantification of stomatal sensitivity to leaf-air vapour pressure deficit and stomatal kinetics, and a case study of trait-mediated niche segregation among congeneric epiphytic bromeliad species on the Caribbean island of Trinidad. The results highlight how divergences in a range of continuous and categorical anatomical traits underpin differences in physiological capacities and sensitivities, which in turn determine environmental relations and ecological distinctiveness. This research project therefore provides critical insights into the mechanistic basis of evolutionary diversification in a highly ecologically important family. It also represents the most comprehensive analysis of the significance of trait variation for ecological differentiation across any major radiation of herbaceous angiosperms.

"June 2002" / Bibliography: leaves 172-198. / viii, 198 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Proposes that the overall outcome of plant interactions along a temporal gradient of resource availability changes from positive during interpulses to negative during pulses. Examines negative interactions between 4 co-dominant chenopod scrubs in arid Acacia papyrocarpa woodlands. Negative interactions were more intense when conditions were least productive. Positive interactions between seedlings also changed over time, depending on the facilitation mechanism. Plant interactions seem to be most intense at the beginning of interpulses when plants are competing for diminishing water, or survivorship is enhanced in the favorable microsites provided by other plants. Later in the interpulse, interactions become less intense as conditions become more stressful and therefore survivorship and growth are affected more by abiotic conditions than plant interactions. / Thesis (Ph.D.)--University of Adelaide, Dept. of Environmental Biology, 2002

"June 2002" / Bibliography: leaves 172-198. / viii, 198 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Proposes that the overall outcome of plant interactions along a temporal gradient of resource availability changes from positive during interpulses to negative during pulses. Examines negative interactions between 4 co-dominant chenopod scrubs in arid Acacia papyrocarpa woodlands. Negative interactions were more intense when conditions were least productive. Positive interactions between seedlings also changed over time, depending on the facilitation mechanism. Plant interactions seem to be most intense at the beginning of interpulses when plants are competing for diminishing water, or survivorship is enhanced in the favorable microsites provided by other plants. Later in the interpulse, interactions become less intense as conditions become more stressful and therefore survivorship and growth are affected more by abiotic conditions than plant interactions. / Thesis (Ph.D.)--University of Adelaide, Dept. of Environmental Biology, 2002

Ecophysiology studies are needed to predict plant responses in relation to climate change. Variations in salinity and inundation are expected to influence the survival and distribution of salt marsh. The following species were chosen to study as they occur in most South African salt marshes and are representative of different tidal ranges; namely Triglochin buchenaui (lower intertidal), Bassia diffusa (upper intertidal succulent) and Limonium linifolium (upper intertidal non-succulent). To simulate climate change conditions as predicted for South Africa, a 3 x 5 controlled experiment of three inundation levels (tidal, submerged and drought) and five salinity levels (0, 8, 18, 35, 45 ppt) was conducted for each species. This resulted in 15 treatments per species. Plant responses were measured over a three month period. Triglochin buchenaui showed significant variation in height (7.57 ± 0.5 to 29 ± 1.55 cm, p < 0.005, DF = 55) with optimum growth at 0 ppt under tidal conditions; leaf area increments and relative growth rates which decreased with increasing salinity under all inundation states. There was almost a cessation of growth under submergence which reduces the plant’s regeneration potential under these conditions. Proline accumulation (1.84 ± 0.23 to 3.36 ± 0.38 mg l-1), response of photosynthetic pigments and electrolyte leakage (8.17 ± 0.80 to 38.36 ± 7.42 percent) were fundamental to osmotic and membrane response regulation. Plants survived in all inundation states at salinity up to 45 ppt, but the optimum range was 0 to 18 ppt, and best water state was the tidal condition. Viable rhizomes were produced under drought conditions. Bassia diffusa (Thunb.) Kuntze plants under submergence died within one month, irrespective of the salinity. Optimum growth occurred in plants of the tidal treatment at 18 ppt, and reduced with increased salinity and drought conditions. Plants in the tidal treatments were more succulent than the drought-treated plants. There was reduced leaf mass and high anthocyanin concentrations in drought-treated plants and these effects increased with salinity. Soil and leaf water potential were positively correlated with anthocyanin concentration in leaves and stems, suggesting anthocyanin accumulated in response to drought and could be an adaptation to lower the plant’s water potential under drought conditions. A shift of anthocyanin from leaves to stems was found in drought-treated plants, and this possibly enables the maximization of photosynthesis in leaves, to complement its role in osmotic balance and photo-protection. Growth of Limonium linifolium showed that the plant was tolerant to a wide range of salinity under both tidal and drought conditions, but was susceptible to complete submergence, with high membrane damage even in tidal-treated plants. Plants died within 2 weeks of complete submergence. Results further indicated that L. linifolium tolerates extreme drought by accumulating large quantities of proline and oxalic acid, which consequently lowers its water potential for uptake of soil water of high salinity. Excess salts were excreted through salt glands. This is an important adaptation for a plant that thrives in a highly variable saline habitat Further investigation of submergence effects on upper intertidal species using B. diffusa showed three key stages in the response. A drop in chlorophyll a+b within 6 hours (4.2 ± 0.2 to 2.4 ± 0.3 mg l-1) with a corresponding increase in carotenoid concentration (0.6 ± 0.1 mg l-1) indicated an immediate response to submergence. Oxalic acid concentration was highest on Day 4 (13.6 mM) as opposed to control levels, indicative of its role in submergence tolerance, thus Day 4 may be the peak of positive acclimation. The third phase was marked by a sharp increase in electrolyte leakage to 47.5 ± 2.6 percent on Day 10, from 9.4 ± 1.4 percent on Day 7, with a corresponding decrease in total dissolved solutes between Days 7 and 10. Results suggest that oxalic acid accumulates under submergence possibly as a stabilizing osmolyte. The threshold for tolerance of the species under submergence is 7 days with membrane damage thereafter. Bassia diffusa would not survive prolonged submergence (> 7 days) but could survive submergence of short duration (< 7 days) through continuous underwater photosynthesis, accumulation of osmolytes such as oxalic acid and carotenoid, and maintenance of relative water content and succulence within control levels. When considered together, results showed that the two upper intertidal species were sensitive to waterlogging and would not survive complete submergence, whereas the lower intertidal species could in addition to its natural range, thrive in conditions typical of the upper intertidal range, namely prolonged dry conditions and high sediment salinity. These results have important implications for the future management of salt marshes under predicted climate change conditions. In permanently open South African estuaries, a landward migration of salt marsh will be possible if coastal squeeze is limited and the rate of landward recruitment is on par with sea level rise. In this case salt marsh species would retain their current zonation while shifting inland. Increased sea storms and saltwater intrusion could lead to high salinity concentration in the sediment and significantly reduce growth of salt-sensitive plants. In estuaries that are temporarily open to the sea, reduced freshwater inflow will result in an increase in mouth closure, high water levels, prolonged submergence, and consequently die back of salt marsh vegetation. On the other hand increased abstraction and drought would result in low water levels and high sediment salinity which would decrease growth and survival of salt marsh. This research has provided new knowledge on the ecophysiology of salt marsh plants which can be used to predict the responses of plants to climate change.

D. Tech. Biotechnology and Food Technology. / Assesses the symbiotic dependency of grain and shrub / tree legumes as well as shrub/tree legume species adaptation to different rainfall regimes within five agroecological zones in Botswana, leaves of the test species were sampled.

Thesis (Ph.D.)--University of Western Australia, 2007.

Various aspects of the ecophysiology of rootless carnivorous Utricularia plants were assessed, with focus on nutrient acquisition and mutualistic interactions within trapping organs. The study includes extracellular enzyme measurements, the evaluation of commensal microbial community structure and function, stable isotope labelling to determine plant carbon allocation, and ion chromatography analyses of trap fluid composition

As sea levels continue to rise, the projected damage that will ensue presents a great challenge for conservation and management of coastal ecosystems in Florida. Since Juncus roemerianus is a common marsh plant throughout Florida with unique growing characteristics that make it a popular restoration plant, this study implemented a 20 week greenhouse split plot experiment to examine the effects of sea level rise on J. roemerianus and ultimately determine its tolerance ranges to salinity and inundation in a high nutrient environment. Overall, salinity level and the interaction effect of salinity level and water level had the greatest effects on measured growth parameters including average mature height, maximum height, density, basal area, root length, and biomass. An inverse relationship between increasing salinity and the measured growth variables was observed with the greatest growth and survivability in 0 ppt water, survivability and reduced growth in 20 ppt water, survivability and little growth in 30 ppt water, and nearly complete senesce in 40 ppt water. This was the first laboratory study to determine the effect of 40 ppt water on J. roemerianus. Elevated water levels resulted in higher growth variables in the 20 ppt, 30 ppt, and 40 ppt treatments while inundated water levels produced higher growth variables in the 0 ppt treatment despite previous research finding inundation to have completely adverse effects on J. roemerianus. It is likely that the high nutrient environment provided for this study is the cause for this anomaly. The results of this study have major implications for the future of coastal ecosystems that are dominated by stands of J. roemerianus in South Florida and can be used in conjunction with studies on bordering marsh plants to predict shifts in the ecosystems of Florida that are responding to sea level rise scenarios. / Includes bibliography. / Thesis(M.S.)--Florida Atlantic University, 2015 / FAU Electronic Theses and Dissertations Collection

Orientador: Gustavo Maia Souza / Banca: Carlos Henrique Britto de Assis Prado / Banca: Gustavo Habermann / Resumo: A estabilidade é fundamental para todos os sistemas biológicos, possibilitando que lidem com a variabilidade ambiental. As propriedades que conferem estabilidade a sistemas biológicos ainda são desconhecidas, mas evidências apontam para a complexidade da dinâmica de certas variáveis fisiológicas e para a força de interação entre elementos de suas redes organizacionais subjacentes. Esta relação foi investigada no sistema de trocas gasosas de espécies florestais tropicais, pertencentes a grupos funcionais distintos: pioneiras e não-pioneiras. O modelo de recursos múltiplos atribui maior flexibilidade fisiológica às espécies pioneiras, mas os métodos geralmente empregados não são capazes de avaliar a estabilidade de um sistema adequadamente. Este estudo foi realizado em séries temporais de trocas gasosas, onde foi possível estimar parâmetros relacionados à estabilidade do sistema. A força de interação entre elementos foi avaliada pela conectância da rede (Cg) e a complexidade da dinâmica de assimilação de CO2 (A) e condutância estomática (gs) pelo algoritmo de entropia aproximada (ApEn). Os resultados revelaram que espécies com perfil fisiológico de pioneira, em condições constantes, apresentam maior Cg e ApEn de gs, possivelmente indicando maior estabilidade. Estas espécies tiveram maior aproveitamento de pulsos de luz ("lightflecks"), o que indicou a importância da modulação de rede (mudanças na conectância) na resposta às variações ambientais, e que maior Cg pode conferir maior capacidade de controle. Além da conectância, grau de acoplamento do sistema ao ambiente foi decisivo na resposta a "sunflecks". Os resultados sugerem que dinâmicas mais complexas estão ligadas a redes com maior conectância, que por sua vez conferem maior capacidade de controle ao sistema, sendo fundamental a capacidade de modulação da rede. / Abstract: Stability is a key feature to all biological systems, enabling them to deal with environmental variability. The properties that promote stability in biological systems are still unknown, but evidences point towards the complexity of the dynamics of certain physiological variables and to the strength of interaction among elements pertaining to its underlying organizational networks. This relationship was investigated in the gasexchange system of tropical forest species, belonging to distinct functional groups: pioneer and non-pioneer. The multiple resources model attributes higher physiological flexibility to pioneer species, but the methods usually employed are not capable of properly evaluating a system's stability. This study was carried out in gas-exchange time-series, enabling the calculation of parameters related to the system's stability. The strength of interaction among elements was evaluated by network connectance (Cg), and the complexity of CO2 assimilation (A) and stomatal conductance (gs) dynamics was evaluated by the algorithm of Approximate Entropy (ApEn). The results revealed that, under constant conditions, species with a pioneer-like physiological profile showed higher Cg and ApEn of gs, possibly indicating greater stability. These species showed higher lightfleck use efficiency, indicating the importance of network modulation (connectance changes) in response to environmental variability, and that higher Cg could provide greater control capability. Besides connectance, the strength of coupling between system and environment was decisive in response to sunflecks. The results suggest that more complex dynamics are linked to higher network connectance, which provide greater control capability to the system, network modulation being fundamental. Also, higher coupling of the system with its environment apparently promotes stability in contexts where environmental variability occurs within the system's control capability. / Mestre

In this thesis, aspects of the reproductive biology of four Banksia species that display in various combinations all the life histories currently recognised in the genus were compared. Species like banksias, from fire prone regions of the world are typically characterised by life histories (traits and organs) that in reference to fire response allow them to be classified as seeders or sprouters. Plants killed by fire and that rely on seed for regeneration are called seeders and those that have the capacity to survive fire and produce vegetative sprouts are called sprouters. The species are Banksia ericifolia, Banksia integrifolia, Banksia oblongifolia, and Banksia serrata. The study was conducted in the Sydney region of Australia, which was arbitrarily divided into North, Central, and Southern provinces for sampling across species. It has been generally hypothesised that several traits are likely to be associated with seeders and sprouters. However, these traits were not always clearly apparent from the author’s studies. It is argued one reason for the anomalies in the expected associated traits is a result of a tendency to assume a evolutionary history that is based on fire as being the primary selection pressure. / Doctor of Philosophy (PhD)