Flora of the southeastern United States; being descriptions of the seed-plants, ferns and fern-allies growing naturally in North Carolina, South Carolin, Georgia, Florida, Tennessee, Alabama, Mississippi, Arkansas, Louisiana and the Indian territory and in Oklahoma and Texas east of the one-hundredth meridian,

Mode of access: Internet.

Variation in Coral Photosynthesis, Respiration and Growth Characteristics in Contrasting Light Microhabitats: An Analogue to Plants in Forest Gaps and Understoreys?

1. The often complex architecture of coral reefs forms a diversity of light microhabitats. Analogous to patterns in forest plants, light variation may drive strategies for efficient light utilization and metabolism in corals. 2. We investigated the spatial distribution of light regimes in a spur-and-groove reef environment and examine the photophysiology of the coral Montipora monasteriata (Forskal 1775), a species with a wide habitat distribution. Specifically, we examined the variation in tissue and skeletal thickness, and photosynthetic and metabolic responses among contrasting light microhabitats. 3. Daily irradiances reaching corals in caves and under overhangs were 1-5 and 30-40% of those in open habitats at similar depth (3-5 m), respectively. Daily rates of net photosynthesis of corals in cave habitats approximated zero, suggesting more than two orders of magnitude variation in scope for growth across habitats. 4. Three mechanisms of photoadaptation or acclimation were observed in cave and overhang habitats: (1) a 20-50% thinner tissue layer and 40-60% thinner skeletal plates, maximizing light interception per unit mass; (2) a two- to threefold higher photosynthetic efficiency per unit biomass; and (3) low rates of dark respiration. 5. Specimens from open and cave habitats displayed a high capacity to acclimate to downshifts or upshifts in irradiance, respectively. However, specimens in caves displayed limited acclimation to further irradiance reduction, indicating that these live near their irradiance limit. 6. Analogous to patterns for some plant species in forest gaps, the morphological plasticity and physiological flexibility of M. monasteriata enable it to occupy light habitats that vary by more than two orders of magnitude.

Nitrogen transfer within and between plants through common mycorrhizal networks (CMNs)

Mycorthizae play a critical role in nutrient capture from soils. Arbuscular mycorrhizae (AM) and ectomycorrhizae (EM) are the most important mycorrhizae in agricultural and natural ecosystems. AM and EM fungi use inorganic NH4+ and NO3-, and most EM fungi are capable of using organic nitrogen. The heavier stable isotope N-15 is discriminated against during biogeochemical and biochemical processes. Differences in N-15 (atom%) or delta(15)N (parts per thousand) provide nitrogen movement information in an experimental system. A range of 20 to 50% of one-way N-transfer has been observed from legumes to nonlegumes. Mycorrhizal fungal mycelia can extend from one plant's roots to another plant's roots to form common mycorrhizal networks (CMNs). Individual species, genera, even families of plants can be interconnected by CMNs. They are capable of facilitating nutrient uptake and flux. Nutrients such as carbon, nitrogen and phosphorus and other elements may then move via either AM or EM networks from plant to plant. Both N-15 labeling and N-15 natural abundance techniques have been employed to trace N movement between plants interconnected by AM or EM networks. Fine mesh (25similar to45 mum) has been used to separate root systems and allow only hyphal penetration and linkages but no root contact between plants. In many studies, nitrogen from N-2-fixing mycorrhizal plants transferred to non-N-2-fixing mycorrhizal plants (one-way N-transfer). In a few studies, N is also transferred from non-N-2-fixing mycorrhizal plants to N-2-fixing mycorrhizal plants (two-way N-transfer). There is controversy about whether N-transfer is direct through CMNs, or indirect through the soil. The lack of convincing data underlines the need for creative, careful experimental manipulations. Nitrogen is crucial to productivity in most terrestrial ecosystems, and there are potential benefits of management in soil-plant systems to enhance N-transfer. Thus, two-way N-transfer warrants further investigation with many species and under field conditions.

La geochimica degli isotopi stabili applicata a reperti scheletrici fossili per ricostruzioni paleoambientali (sito archeologico di Arslantepe –Turchia).

Il sito archeologico di Arslantepe (provincia di Malatya, Turchia) rappresenta un caso di studio di potenziale interesse per l’interazione tra i mutamenti climatici e la storia della civiltà. Il sito, occupato quasi ininterrottamente per un periodo di tempo relativamente lungo (6250-2700 BP), ha fornito una grande quantità di reperti ossei, distribuiti lungo una stratigrafia archeologica relativamente dettagliata e supportata da datazioni al radiocarbonio. Tali reperti, indagati con le tecniche della geochimica degli isotopi stabili, possono costituire degli efficaci proxy paleoclimatici. In questo lavoro è stata studiata la composizione isotopica di 507 campioni di resti ossei umani e animali (prevalentemente pecore, capre, buoi). I rapporti isotopici studiati sono relativi a ossigeno (δ18Ocarb, δ18Oph), carbonio (δ13Ccarb, δ13Ccoll) e azoto (δ15N), misurati nella frazione minerale e organica dell’osso; la variabilità nel tempo di questi parametri, principalmente legati alla paleonutrizione, può essere correlata, direttamente o indirettamente, a cambiamenti dei parametri ambientali quali temperatura e umidità atmosferiche. I risultati indicano che la dieta degli animali selvatici e domestici di Arslantepe era quasi esclusivamente a base di piante a ciclo fotosintetico C3, generalmente tipiche di climi umidi o temperati. La presenza di piante C4, più tipiche di condizioni aride, sembrerebbe essere riconoscibile solamente nella dieta del bue (Bos taurus). La dieta umana era esclusivamente terrestre a base di cereali e carne di caprini con una percentuale esigua o del tutto assente di carne di maiale e bue. Dal punto di vista paleoclimatico il principale risultato del lavoro consiste nel riconoscimento della preservazione di un segnale paleoclimatico a lungo termine (δ18OW, composizione isotopica dell’ossigeno dell’acqua ingerita), che identifica un massimo relativo di umidità attorno al 5000 BP e che si correla, per andamento e ampiezza della variazione a record paleoclimatici di sedimenti lacustri collocati in regioni adiacenti all’area di studio. Sulla base del confronto dei tre segnali isotopici sono state inoltre riconosciute due anomalie climatiche siccitose a breve termine, apparentemente riferibili a due episodi di aridità a scala regionale documentati in letteratura.

The feasibility of hybrid solar-biomass power plants in India

We assess the feasibility of hybrid solar-biomass power plants for use in India in various applications including tri-generation, electricity generation and process heat. To cover this breadth of scenarios we analyse, with the help of simulation models, case studies with peak thermal capacities ranging from 2 to 10 MW. Evaluations are made against technical, financial and environmental criteria. Suitable solar multiples, based on the trade-offs among the various criteria, range from 1 to 2.5. Compared to conventional energy sources, levelised energy costs are high - but competitive in comparison to other renewables such as photovoltaic and wind. Long payback periods for hybrid plants mean that they cannot compete directly with biomass-only systems. However, a 1.2-3.2 times increase in feedstock price will result in hybrid systems becoming cost competitive. Furthermore, in comparison to biomass-only, hybrid operation saves up to 29% biomass and land with an 8.3-24.8 $/GJ/a and 1.8-5.2 ¢/kWh increase in cost per exergy loss and levelised energy cost. Hybrid plants will become an increasingly attractive option as the cost of solar thermal falls and feedstock, fossil fuel and land prices continue to rise. In the foreseeable future, solar will continue to rely on subsidies and it is recommended to subsidise preferentially tri-generation plants. © 2012 Elsevier Ltd.

Solar thermal collectors for use in hybrid solar-biomass power plants in India

This thesis examined solar thermal collectors for use in alternative hybrid solar-biomass power plant applications in Gujarat, India. Following a preliminary review, the cost-effective selection and design of the solar thermal field were identified as critical factors underlying the success of hybrid plants. Consequently, the existing solar thermal technologies were reviewed and ranked for use in India by means of a multi-criteria decision-making method, the Analytical Hierarchy Process (AHP). Informed by the outcome of the AHP, the thesis went on to pursue the Linear Fresnel Reflector (LFR), the design of which was optimised with the help of ray-tracing. To further enhance collector performance, LFR concepts incorporating novel mirror spacing and drive mechanisms were evaluated. Subsequently, a new variant, termed the Elevation Linear Fresnel Reflector (ELFR) was designed, constructed and tested at Aston University, UK, therefore allowing theoretical models for the performance of a solar thermal field to be verified. Based on the resulting characteristics of the LFR, and data gathered for the other hybrid system components, models of hybrid LFR- and ELFR-biomass power plants were developed and analysed in TRNSYS®. The techno-economic and environmental consequences of varying the size of the solar field in relation to the total plant capacity were modelled for a series of case studies to evaluate different applications: tri-generation (electricity, ice and heat), electricity-only generation, and process heat. The case studies also encompassed varying site locations, capacities, operational conditions and financial situations. In the case of a hybrid tri-generation plant in Gujarat, it was recommended to use an LFR solar thermal field of 14,000 m2 aperture with a 3 tonne biomass boiler, generating 815 MWh per annum of electricity for nearby villages and 12,450 tonnes of ice per annum for local fisheries and food industries. However, at the expense of a 0.3 ¢/kWh increase in levelised energy costs, the ELFR increased saving of biomass (100 t/a) and land (9 ha/a). For solar thermal applications in areas with high land cost, the ELFR reduced levelised energy costs. It was determined that off-grid hybrid plants for tri-generation were the most feasible application in India. Whereas biomass-only plants were found to be more economically viable, it was concluded that hybrid systems will soon become cost competitive and can considerably improve current energy security and biomass supply chain issues in India.

A geometrical model for surface roughness prediction when face milling Al 7075-T7351 with square insert tools

Surface quality is important in engineering and a vital aspect of it is surface roughness, since it plays an important role in wear resistance, ductility, tensile, and fatigue strength for machined parts. This paper reports on a research study on the development of a geometrical model for surface roughness prediction when face milling with square inserts. The model is based on a geometrical analysis of the recreation of the tool trail left on the machined surface. The model has been validated with experimental data obtained for high speed milling of aluminum alloy (Al 7075-T7351) when using a wide range of cutting speed, feed per tooth, axial depth of cut and different values of tool nose radius (0.8. mm and 2.5. mm), using the Taguchi method as the design of experiments. The experimental roughness was obtained by measuring the surface roughness of the milled surfaces with a non-contact profilometer. The developed model can be used for any combination of material workpiece and tool, when tool flank wear is not considered and is suitable for using any tool diameter with any number of teeth and tool nose radius. The results show that the developed model achieved an excellent performance with almost 98% accuracy in terms of predicting the surface roughness when compared to the experimental data. © 2014 The Society of Manufacturing Engineers.

Correlates of leaf optical properties in tropical forest sun and extreme-shade plants

Thirteens hade-adaptedr ain forest species were comparedw ith twelve sun-adaptedt ropical forest species for correlates to leaf optical properties (described previously in Amer. J. Bot. 73: 1100-1108). The two samples were similar in absorptance of quanta for photosynthesis, but the shade-adaptedt axa: 1) had significantlyl ower specificl eaf weights,i ndicatinga more metabolically efficient production of surface for quantum capture; 2) synthesized less chlorophyll per unit area; and 3) used less chlorophyll for capturing the same quanta for photosynthesis. The anatomical features that best correlate with this increased efficiency are palisade cell shape and chloroplast distribution. Palisade cells with more equal dimensions have more chloroplasts on their abaxial surfaces. This dense layer of chloroplasts maximizes the light capture efficiency limited by sieve effects. The more columnar palisade cells of sun-adapted taxa allow light to pass through the central vacuoles and spaces between cells, making chloroplasts less efficient in energy capture, but allowing light to reach chloroplasts in the spongy mesophyll. Pioneer species may be an exception to these two groups of species. Three pioneer taxa included in this study have columnar palisade cells that are extremely narrow and packed closely together. This layer allows little penetration of light, but exposure of the leaf undersurface may provide illumination of spongy mesophyll chloroplasts in these plants.

Simulating Forest Shade to Study the Developmental Ecology of Tropical Plants: Juvenile Growth in Three Vines in India

Both light quantity and quality affect the development and autoecology of plants under shade conditions, as in the understorey of tropical forests. However, little research has been directed towards the relative contributions of lowered photosynthetic photon flux density (PPFD) versus altered spectral distributions (as indicated by quantum ratios of 660 to 730 nm, or R:FR) of radiation underneath vegetation canopies. A method for constructing shade enclosures to study the contribution of these two variables is described. Three tropical leguminous vine species (Abrus precatorius L., Caesalpinia bondicela Fleming and Mucuna pruriens (L.) DC.) were grown in two shade enclosures with 3-4% of solar PPFD with either the R:FR of sunlight (1.10) or foliage shade (0.33), and compared to plants grown in sunlight. Most species treated with low R:FR differed from those treated with high R:FR in (1) percent allocation to dry leaf weight, (2) internode length, (3) dry stem weight/length, (4) specific leaf weight, (5) leaf size, and (6) chlorophyll a/b ratios. However, these plants did not differ in chlorophyll content per leaf dry weight or area. In most cases the effects of low R:FR and PPFD were additional to those of high R:FR and low PPFD. Growth patterns varied among the three species, but both low PPFD and diminished R:FR were important cues in their developmental responses to light environments. This shadehouse system should be useful in studying the effects of light on the developmental ecology of other tropical forest plants.

Leaf Optical Properties of Rainforest Sun and Extreme Shade Plants

The opticalp ropertieso f the leaves of twelve tropicals un speciesa nd thirteent ropicale xtreme shade species were examinedw ith an integratings pherea ttachedt o a spectroradiometerM. easurements of diffuse reflectance and transmittance allowed calculations of absorptance, 350- 1,100 nm. Althoughs ome shade species absorbedh igherp ercentageso f quantumf lux densities for photosynthesis (400-700 nm, PPFD) than the mean for the sun species, the sun and shade species as groups were not significantly different from each other: 90.2, S.D. 3.6% for shade species and 88.6, S.D. 2.4% for the sun species. The groups of species did not differ in total absorptance of energy 350-1,100 nm. Furthermore, the sun and shade species were identical in theirs hifto f absorptancea t wavelengthsb etween6 50 and 750 nm. The anthocyanicc oloration of the leaf undersurfaceso f two species polymorphicf or this characteristic( Trionela hirsuta and Ischnosciphonp ruinosus)i s correlatedw ith increaseda bsorptancea t the uppere nd of the action spectrum of photosynthesis. Although sun and shade species have similar optical properties, the energy investment (as documented by dry wt per unit area of leaf surface) is much less for the shade species.

A multi-scale assessment of physiological processes in arctic tundra plants under natural and simulated climate change scenarios

Climate warming is predicted to cause an increase in the growing season by as much as 30% for regions of the arctic tundra. This will have a significant effect on the physiological activity of the vascular plant species and the ecosystem as a whole. The need to understand the possible physiological change within this ecosystem is confounded by the fact that research in this extreme environment has been limited to periods when conditions are most favorable, mid June–mid August. This study attempted to develop the most comprehensive understanding to date of the physiological activity of seven tundra plant species in the Alaskan Arctic under natural and lengthened growing season conditions. Four interrelated lines of research, scaling from cellular signals to ecosystem processes, set the foundation for this study. ^ I established an experiment looking at the physiological response of arctic sedges to soil temperature stress with emphasis on the role of the hormone abscisic acid (ABA). A manipulation was also developed where the growing season was lengthened and soils were warmed in an attempt to determine the maximum physiological capacity of these seven vascular species. Additionally, the physiological capacities of four evergreens were tested in the subnivean environment along with the potential role anthocyanins play in their activity. The measurements were scaled up to determine the physiological role of these evergreens in maintaining ecosystem carbon fluxes. ^ These studies determined that soil temperature differentials significantly affect vascular plant physiology. ABA appears to be a physiological modifier that limits stomatal processes when root temperatures are low. Photosynthetic capacity was limited by internal plant physiological mechanisms in the face of a lengthened growing season. Therefore shifts in ecosystem carbon dynamics are driven by changes in species composition and biomass production on a per/unit area basis. These studies also found that changes in soil temperatures will have a greater effect of physiological processes than would the same magnitude of change in air temperature. The subnivean environment exhibits conditions that are favorable for photosynthetic activity in evergreen species. These measurements when scaled to the ecosystem have a significant role in limiting the system's carbon source capacity. ^

Seed dispersal and reproduction patterns among Everglades plants

In this study three aspects of sexual reproduction in Everglades plants were examined to more clearly understand seed dispersal and the allocation of resources to sexual reproduction—spatial dispersal process, temporal dispersal of seeds (seedbank), and germination patterns in the dominant species, sawgrass (Cladium jamaicense). Community assembly rules for fruit dispersal were deduced by analysis of functional traits associated with this process. Seedbank ecology was investigated by monitoring emergence of germinants from sawgrass soil samples held under varying water depths to determine the fate of dispersed seeds. Fine-scale study of sawgrass fruits yielded information on contributions to variation in sexually produced propagules in this species, which primarily reproduces vegetatively. It was hypothesized that Everglades plants possess a set of functional traits that enhance diaspore dispersal. To test this, 14 traits were evaluated among 51 species by factor analysis. The factorial plot of this analysis generated groups of related traits, with four suites of traits forming dispersal syndromes. Hydrochory traits were categorized by buoyancy and appendages enhancing buoyancy. Anemochory traits were categorized by diaspore size and appendages enhancing air movement. Epizoochory traits were categorized by diaspore size, buoyancy, and appendages allowing for attachment. Endozoochory traits were categorized by diaspore size, buoyancy, and appendages aiding diaspore presentation. These patterns/trends of functional trait organization also represent dispersal community assembly rules. Seeds dispersed by hydrochory were hypothesized to be caught most often in the edge of the north side of sawgrass patches. Patterns of germination and dispersal mode of all hydrochorous macrophytes with propagules in the seedbank were elucidated by germination analysis from 90 soil samples collected from 10 sawgrass patches. Mean site seed density was 486 seeds/m2 from 13 species. Most seeds collected at the north side of patches and significantly in the outer one meter of the patch edge (p = 0.013). Sawgrass seed germination was hypothesized to vary by site, among individual plants, and within different locations of a plant’s infructescence. An analysis of sawgrass fruits with nested ANOVAs found that collection site and interaction of site x individual plant significantly affect germination ability, seed viability, and fruit size (p ≤ 0.050). Fruit location within a plant’s infructescence did not significantly affect germination. As for allocation of resources to sexual reproduction, only 17.9% of sawgrass seeds germinated and only 4.8% of ungerminated seeds with fleshy endosperm were presumed viable, but dormant. Collectively, only 22% of all sawgrass seeds produced were viable.

Anti-diarrheal plants of central Anatolia: Do they inhibit diarrhea-causing bacteria?

Infectious diarrhea results in 2 to 5 million deaths worldwide per year, and treatments that are safe, effective, and readily available are under investigation. The field of medicinal ethnobotany focuses on plants that are used by different cultural groups for treating various diseases and evaluates these plants for efficacy and cytotoxicity. In the present study, ethnobotanical research was conducted with Central Anatolian villagers in Turkey. Folk concepts and etiologies surrounding diarrhea were analyzed, as were salient plant-based remedies for diarrhea. Reviewing the literature, 91 plant species were described as anti-diarrheal in all of Turkey. In Central Anatolia, villagers described 35 species. For continued research via bactericidal and bacteriostatic bioassays, 15 plants were selected. Methanolic and aqueous extracts of medicinally used plant parts were evaluated for inhibitory properties against 10 diarrhea-causing bacteria in the first bioassay, and later 21 bacteria in a second assay utilizing spectrophotometry. The cytotoxic properties were also evaluated in an Alamar Blue Assay using HepG-2, PC-3, and SkMEL-5 human cell lines. While several extracts showed bactericidal and bacteriostatic properties, the methanolic extract of R. canina galls inhibited the most bacteria at the lowest concentrations. They were not cytotoxic. Thus, R. canina methanolic gall extracts were selected for bio-assay guided fractionation. Antibacterial activity was maintained in the third fraction which was composed of almost pure ellagic acid. The bioassay was repeated with standard ellagic acid, and the polyphenol retained potency in inhibiting multiple bacterial strains. Several other extracts showed promise for safe, effective anti-bacterial remedies for diarrhea.

Seed Dispersal and Reproduction Patterns Among Everglades Plants

In this study three aspects of sexual reproduction in Everglades plants were examined to more clearly understand seed dispersal and the allocation of resources to sexual reproduction— spatial dispersal process, temporal dispersal of seeds (seedbank), and germination patterns in the dominant species, sawgrass (Cladium jamaicense). Community assembly rules for fruit dispersal were deduced by analysis of functional traits associated with this process. Seedbank ecology was investigated by monitoring emergence of germinants from sawgrass soil samples held under varying water depths to determine the fate of dispersed seeds. Fine-scale study of sawgrass fruits yielded information on contributions to variation in sexually produced propagules in this species, which primarily reproduces vegetatively. It was hypothesized that Everglades plants possess a set of functional traits that enhance diaspore dispersal. To test this, 14 traits were evaluated among 51 species by factor analysis. The factorial plot of this analysis generated groups of related traits, with four suites of traits forming dispersal syndromes. Hydrochory traits were categorized by buoyancy and appendages enhancing buoyancy. Anemochory traits were categorized by diaspore size and appendages enhancing air movement. Epizoochory traits were categorized by diaspore size, buoyancy, and appendages allowing for attachment. Endozoochory traits were categorized by diaspore size, buoyancy, and appendages aiding diaspore presentation. These patterns/trends of functional trait organization also represent dispersal community assembly rules. Seeds dispersed by hydrochory were hypothesized to be caught most often in the edge of the north side of sawgrass patches. Patterns of germination and dispersal mode of all hydrochorous macrophytes with propagules in the seedbank were elucidated by germination analysis from 90 soil samples collected from 10 sawgrass patches. Mean site seed density was 486 seeds/m2 from 13 species. Most seeds collected at the north side of patches and significantly in the outer one meter of the patch edge (p = 0.013). Sawgrass seed germination was hypothesized to vary by site, among individual plants, and within different locations of a plant’s infructescence. An analysis of sawgrass fruits with nested ANOVAs found that collection site and interaction of site x individual plant significantly affect germination ability, seed viability, and fruit size (p < 0.050). Fruit location within a plant’s infructescence did not significantly affect germination. As for allocation of resources to sexual reproduction, only 17.9% of sawgrass seeds germinated and only 4.8% of ungerminated seeds with fleshy endosperm were presumed viable, but dormant. Collectively, only 22% of all sawgrass seeds produced were viable.

(Tables 1-3) Water chemistry of cloud forest streams at baseflow conditions, Rio San Francisco, Ecuador

We investigated controls on the water chemistry of a South Ecuadorian cloud forest catchment which is partly pristine, and partly converted to extensive pasture. From April 2007 to May 2008 water samples were taken weekly to biweekly at nine different subcatchments, and were screened for differences in electric conductivity, pH, anion, as well as element composition. A principal component analysis was conducted to reduce dimensionality of the data set and define major factors explaining variation in the data. Three main factors were isolated by a subset of 10 elements (Ca2+, Ce, Gd, K+, Mg2+, Na+, Nd, Rb, Sr, Y), explaining around 90% of the data variation. Land-use was the major factor controlling and changing water chemistry of the subcatchments. A second factor was associated with the concentration of rare earth elements in water, presumably highlighting other anthropogenic influences such as gravel excavation or road construction. Around 12% of the variation was explained by the third component, which was defined by the occurrence of Rb and K and represents the influence of vegetation dynamics on element accumulation and wash-out. Comparison of base- and fast flow concentrations led to the assumption that a significant portion of soil water from around 30 cm depth contributes to storm flow, as revealed by increased rare earth element concentrations in fast flow samples. Our findings demonstrate the utility of multi-tracer principal component analysis to study tropical headwater streams, and emphasize the need for effective land management in cloud forest catchments.