Low-water landscaping is an essential tool for water conservation in the arid Intermountain West (IMW) for managing limited supplies and population-driven increased demand. The IMW harbors a large number of drought-tolerant native species that have potential for use in the low-water use landscape (LWL). However, many species are not available in the nursery trade due to their morphological confusion and establishment difficulty in the managed landscapes. The overall goal of this study is to elucidate morphological, ecophysiological, and genetic distinctions within two IMW native plant genera containing species with high urban low-water landscape potential.

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Species in the genus Populus (poplars) have shown the potential to be utilized as short rotation woody crops for bioenergy production in the Southeast. A lack of knowledge on which poplar taxa perform best on marginal sites throughout the Southeast exists. Through measurement of relationships between growth metrics, water usage and physiological parameters of 2400 poplar trees, I was able to assess: 1) early rotation suitability of numerous poplar varietals to be grown as bioenergy feedstocks in northeast Mississippi, and 2) the effectiveness of early rotation physiological parameters in predicting future productivity and water usage. Overall findings from this study suggest that trees with D x M parentage may be best fit for large-scale plantation growth in the Southeast. They demonstrated low mortality and collectively grew the tallest of all taxa. Early-rotation physiology demonstrated mixed results in predicting future growth and water usage. Findings from this study will be used in future bioenergy feedstock selection.

"November 2001" / Bibliography: leaves 132-156. / xii, 166 leaves : ill. (some col.), plates (col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Focusses on the ecophysiology of Ecklonia radiata and quantifies its carbon contribution to further elucidate E. radiata's role in the nearshore marine environment. The photosynthesis-irradiance response of E. radiata was investigated in situ throughout the year and across the dept profile. A clear seasonal change in photokinetic parameters was detected and provided strong evidence of a seasonal acclimation response. Changes in photokinetic parameters across the depth profile were less pronounced and a significant decline in productivity occurred at deeper depths. The acclimation state of E radiata did alter across the depth profile. / Thesis (Ph.D.)--University of Adelaide, Dept. of Environmental Biology, 2002

Puccinellia (puccinellia ciliata) and tall wheatgrass (Thinopyrum ponticum) often show ecological zonation in saline landscapes, with puccinellia occurring in less elevated more saline/waterlogged locations, and tall wheatgrass occurring in more elevated less saline/waterlogged locations. The aims of this study were to: (a) characterize the observed ecological zonation at a field site, (b) quantify the effects of variables likely to explain growth differences of the two plants in glasshouse experiments, and (c) identify and compare anatomical and physiological mechanisms that explain these zonation patterns. At an experiment in the field near Kojonup (0522824E, 6244579N), puccinellia was found to colonise the lower more severely salinised and waterlogged zones of the landscape, with tall wheatgrass occupying the higher less affected zones. These differences in zonation were clearly associated with variance in soil salinity and water-table depth. Glasshouse experiments in soil revealed that low pH values, low calcium concentrations and variation in salinity alone did not explain the ecological zonation observed in the field. However, there was a substantial difference in the responses of the two plant species to waterlogging in combination with salinity. Puccinellia grew better under saline waterlogged conditions than tall wheatgrass, which was associated with better regulation of Na+ and K+ under saline/waterlogged conditions than in tall wheatgrass. Under non-saline conditions, waterlogging (hypoxia) decreased shoot weights in puccinellia by 15% and in tall wheatgrass by 20%. Similar growth results were obtained in nutrient solution culture, where waterlogging was simulated by lowering the oxygen in solutions through bubbling with N2 gas. Under saline hypoxic conditions, puccinellia, compared to tall wheatgrass, showed increased growth and maintenance of selectivity of K+ over Na+ across adventitious roots. Solution experiments revealed adaptive traits responsible for conveying better growth and ion maintenance present in puccinellia, but not tall wheatgrass, such as inducement of a barrier to radial oxygen loss in the basal regions of adventitious roots (not previously reported in the literature for puccinellia), formation of root aerenchyma and packing of cortical cells and suberin deposition in hypodermal and endodermal root cell layers. These results should assist in targeting pasture species, and predicting their growth response, in saline and waterlogged landscapes. Further work on examining the genetic material of puccinellia is warranted in order to identify genes that could be transferred into crop plants to convey salt and waterlogging tolerance.

This study determined the effect of hypoxia on air-breathing onset and physiological and morphological characters in larvae of the air breathing fishes Trichopodus trichopterus and Betta splendens. Larvae were exposed intermittently (12/12 h daily) to 20, 17, and 14 kPa of PO2 from 1 to 40 days post-fertilization. Survival, onset of air breathing, wet body mass, O2, Pcrit were measured every 5 dpf. Hypoxia advanced by 4 days, and delayed by 9 days, the onset of air breathing in Betta and Trichopodus, respectively. Hypoxia increased larval body length, wet mass, and labyrinth organ respiratory surface of Betta, but did not affect these factors in Trichopodus. Hypoxic exposure increased O2 by 50-100% at each day throughout larval development in Betta, but had no effect on larval Trichopodus. Hypoxia decreased Pcrit in Betta by 37%, but increased Pcrit in Trichopodus by 70%. Larval Betta reared in hypoxia showed a modified heart rate:opercular rate ratio (3:1 to 2:1), but these changes did not occur in Trichopodus. Compared to Betta, the blood of Trichopodus had a higher P50 and much smaller Bohr and Root effects. These interspecific differences are likely due to ecophysiological differences: Betta is a non- obligatory air-breather after 36 dpf with a slow lifestyle reflected in its low metabolism, while Trichopodus is an obligatory air-breather past 32 dpf with an athletic fast lifestyle and accompanying high metabolism.

A thesis submi.tted to the Faculty of Science, University of the witwatersrand, Johannesburg I in the fulfillmen,,;"o:f' 't\ :he requirements of the Degree of Magister Scienta~. June 1992 / The present study was undertaken; withirl the South African " savannas, to provide "insight into a j;unctional classification of aavanna plants using ecophY$iologiLcal charact~:t's.THe pri.mary r.:>bjective of this study Was to investigate the vari.ation of these tt'aits throughout: the savanna, aridto relate this variation to plant avail.able moisture and nU~l'ie~~s• !t was conclu.ded that~ 1) no formal or specialized strategies have evolved within a number of the study sites, .2) unlike the woody component I neither divergellce nor convergence was demonstrated within the grass layer, c' 3) plant aVailable nutrients did not appear to be a major determinant of either component. Although plant available moistur~ proved to be unimportant in the woody layer, it did playa role as a determinant of the grass layer, and 4) constancy of the plant traits was not demonstrated to \": OCCllr over the gr~~ing season. A succeisf',\lclassification' would require the components to be separat~pl specific determinan.ts be identified for each component, and an element of time be included into both edaphic and biotic measurements.

Master of Science / Department of Biology / Jesse B. Nippert / Jesse B. Nippert / Anthropogenic climate change is likely to alter the function and composition of ecosystems worldwide through increased precipitation variability and temperatures. To predict ecosystem responses, a greater understanding of the physiological and growth responses of plants is required. Dominant species drive ecosystem responses, and it is essential to understand how they respond to understand potential ecosystem changes. Dominant species, such as switchgrass (Panicum virgatum L.), posses large genotypic and phenotypic variability, which will impact the degree of responses to projected climate changes. I studied the physiological and growth responses of switchgrass, a common perennial warm-season C4 grass that is native to the tallgrass prairie, to alterations in precipitation amount and temperature. The first experiment I conducted focused on the responses of three ecotypes of P. virgatum to three precipitation regimes (average, 25% below, 25% above). I concluded that the physiological responses of photosynthesis, stomatal conductance, transpiration, dark-adapted fluorescence, and mid-day water potential in P. virgatum were explained by ecotypic differences. Robust responses to altered precipitation were seen in the water use efficiency, mid-day water potential, and aboveground biomass. Ecotypic differences were also seen in several aboveground biomass variables, and most strikingly in flowering times and rates. There were few interactions between ecotype and precipitation, suggesting precipitation is a strong driver of biomass production, whereas adaption of ecotypes to their local environment affects physiological processes. A second experiment studied the response of local populations of P. virgatum to nocturnal warming. Results showed significant differences in daytime E, daytime gs, and flowering phenology between treatments. Differences in aboveground biomass were between topographic positions. I concluded that water availability, based on topographic position, is a strong driver of P. virgatum aboveground biomass production, but nocturnal warming has the potential to impact flowering phenology, physiological responses, and exacerbate plant water stress. I also reviewed the literature on the ecological effects of implementing switchgrass cultivation for biofuel. From the literature review, I concluded that large-scale switchgrass cultivation will have widespread ecological impacts. If landscape heterogeneity is maintained through harvest rotations, no till farming, and mixed species composition, ecosystem services can be maintained while providing economic value.

Le Loup ou Bar Dicentrarchus labrax est une espèce euryhaline dont les femelles pondent généralement en eau de mer. Pendant son cycle de vie, des migrations vers les estuaires et les lagunes, peuvent exposer très tôt les jeunes stades à des variations de salinité. Les mécanismes de l'osmorégulation sont bien connus chez les prélarves, les larves et les adultes de D. labrax en eau de mer (EM, 38) et en eau de mer diluée (EMD, 5), cependant les possibilités d'osmorégulation et leurs mécanismes sont inconnus chez les embryons. Le but de cette étude a été d'évaluer la mise en place de la fonction osmorégulatrice chez les embryons de D. labrax.Tout d'abord le développement embryonnaire des différents sites osmorégulateurs a été décrit, en se focalisant sur le tube digestif, en incluant le pharynx et les premières fentes branchiales. La formation de ces structures débute au stade 12 somites (S) et a été décrite jusqu'à l'ouverture de la bouche, 5 jours après l'éclosion.En second lieu, le lieu et la cinétique d'apparition des premières cellules osmorégulatrices, les « ionocytes » ont été recherchés. Ces cellules ont été identifiées au stade 12S sur la membrane de la vésicule vitelline et au niveau des premières fentes branchiales et du tube digestif primitif au stade 14S. La fonctionnalité de ces cellules a été étudiée grâce à des immunomarquages des principales protéines transmembranaires impliqués dans l'osmorégulation [l'ATPase Na+/K+ (NKA), le cotransporteur Na+/K+/2Cl- (NKCC) et le canal à chlore (CFTR)], et avec une étude ultrastructurale. Des ionocytes potentiellement fonctionnels sont présents à partir du stade 25S au niveau de la membrane de la vésicule vitelline et du tube digestif primitif, mais les ionocytes des premières fentes branchiales ne sont pas totalement fonctionnels à l'éclosion. L'existence d'un phénomène de boisson passive qui permettrait la régulation hydrique chez D. labrax est envisagé.Finalement, l'osmorégulation embryonnaire existant en EM et en EMD a été étudiée. Des mesures nanoosmométriques des fluides embryonnaires indiquent une capacité à hyper- et hypo-osmoréguler. Cependant, en EMD, des analyses en qRT-PCR et des immunomarquages de NKA, NKCC et CFTR révèlent que les mécanismes de l'hyper-osmorégulation peuvent limiter les pertes ioniques mais ne sont pas suffisamment efficaces pour permettre une acclimatation totale à l'EMD à ce stade très précoce. / The European sea bass Dicentrarchus labrax is a euryhaline species which usually spawns in seawater. Due to its life cycle that includes migrations to lagoon and estuaries, young stages can be exposed early to salinity variations. Osmoregulatory patterns are well known in prelarvae, larvae and adults D. labrax in seawater (SW, 38) and in dilute seawater (DSW, 5), but the possibility and mechanisms of embryonic osmoregulation are still unknown. The goal of this study was to investigate the occurence of the omoregulatory function in the embryos of D. Labrax.First, the embryonic development of the different osmoregulatory sites was described, focusing on the digestive system including the pharynx and the first gill slits. The formation of these structures is initialized at stage 12 somites (S) and was described throughout the opening of the mouth five days after hatching.Secondarily, the time and the location of the occurrence of the first osmoregulatory cells, the ionocytes were followed. These cells were identified at stage 12S on the yolk sac membrane and at stage 14S in the first gill slits and in the posterior primitive gut. The functionality of these cells was studied, using immunostaining of the main ionic transporters involved in osmoregulation [the Na+/K+ ATPase (NKA), the Na+/K+/2Cl- cotransporter (NKCC) and the chloride channel (CFTR)], and through ultrastructural investigations. Potentially functional ionocytes are present from stage 25S in the yolk sac membrane and in the gut, but gill slits ionocytes are not fully functional at hatching. Passive drinking is suspected to regulate water balance in D. labrax.Finally, the embryonic osmoregulation in SW and DSW was investigated. Nanoosmometry measurements of the embryonic fluids demonstrated some capabilities of hyper- and hypo-osmoregulation. However, in DSW, qRT-PCR and imunostaining of NKA, NKCC and CFTR, reveal that hyper-osmoregulatory mechanisms can only limit ion loss but are not efficient enough to allow a full acclimation at this early life stage.

La production hydroélectrique est fortement impactée par la sédimentation dans les retenues de barrages, qui sont influencés par l'occupation du sol, l'infiltration et les interactions entre les eaux de surface et les aquifères. Pour le paiement des Services Hydrologiques Environnementaux au Costa Rica, une quantification de l'impact des utilisations des terres cultivées en café sur le fonctionnement des bassins est nécessaire. Cette thèse vise à : 1) étudier les composantes du bilan hydrologique dans un bassin agroforestier récemment installé 2) à quantifier les flux d'eau et de sédiments à différentes échelles : de la parcelle au bassin et de l'événement de crue à l'échelle annuelle, et 3) à simuler le bilan hydrique et la production de sédiments en tenant compte du ruissellement sur les versants et les routes. Les processus hydrologiques, écophysiologiques et de transfert de sédiments ont été suivis sur le bassin (pluie, débit, évapotranspiration, humidité du sol, niveau de l'aquifère, turbidité) et les parcelles (ruissellement de surface et érosion). Un nouveau modèle éco- hydrologique a été développé pour simuler les termes du bilan hydrologique et de sédiments. Des améliorations sont en cours pour tenir compte de l'effet des routes sur la genèse du ruissellement de surface et de l'érosion. Le faible ruissellement de surface, la faible érosion des parcelles et la faible production de sédiments, compte-tenu des conditions biophysiques et des pratiques de gestion (arbres d'ombrage, désherbage), offrent clairement des Services Ecosystémiques en réduisant les transferts superficiels de pesticides et de sédiments et en permettant une bonne régulation du débit de rivière. / The profitability of hydropower is affected by soil erosion and sedimentation in dam reservoirs, which are influenced by land use, infiltration and aquifer interactions with surface water. In order to promote the payment of Hydrological Environmental Services (HES) in Costa Rica, a quantitative assessment of the impact of land uses (such as coffee farming) on the functioning of drainage basins is required. This thesis seeks: 1) to study the water balance partitioning in a newly installed coffee agroforestry basin 2) to estimate the water and sediment yield at various spatio-temporal scales: from plot to basin and from event to annual scale; and 3) to simulate the water and sediment yields, at both annual and peakflow scale, by including the surface runoff from hillslopes and roads. The main hydrological, ecophysiological and sediment processes were monitored during one year at the basin (rainfall, streamflow, evapotranspiration, soil humidity, aquifer level, turbidity) and at the plots (surface runoff and erosion). A new eco-hydrological model was developed to close the water balance, and the annual sediment yield was also quantified. Improvements are in progress to take into account the effect of roads in surface runoff generation. The low surface runoff, low plot erosion and low basin sediment yield observed under the current biophysical conditions (andisol) and management practices (no tillage, planted trees, bare soil kept by weeding), offer potential HES by reducing the superficial displacement capacity for fertilizers and pesticides, yielding low sediment loads and regulating streamflow variability through highly efficient mechanisms of aquifer recharge-discharge.