Heat stress reduces stomatal numbers in Ginkgo biloba: Implications for the stomatal method of palaeo-atmospheric [CO] reconstruction during episodes of global warming.

The stomata of fossil plants are commonly used as proxies to reconstruct palaeo-atmospheric carbon dioxide concentrations (palaeo-[CO]). Stomatal reconstruction of palaeo-[CO] during global greenhouse periods or episodes of global warming, are particularly important to our understanding of the role of CO as a climate system driver. However, the efficacy of the 'stomatal method' for palaeo-[CO] reconstruction depends upon the strength of the inverse relationship between stomatal number and the [CO] in which the leaf developed.

The functional significance of the stomatal size to density relationship: Interaction with atmospheric [CO] and role in plant physiological behaviour.

The limits for stomatal conductance are set by stomatal size (SS) and density (SD). An inverse relationship between SS and SD has been observed in fossil and living plants. This has led to hypotheses proposing that the ratio of SS to SD influences the diffusion pathway for CO and degree of physiological stomatal control.

Lipid Peroxidation and Chlorophyll Fluorescence of Photosystem II Performance during Drought and Heat Stress is Associated with the Antioxidant Capacities of C3 Sunflower and C4 Maize Varieties.

Agricultural production is predicted to be adversely affected by an increase in drought and heatwaves. Drought and heat damage cellular membranes, such as the thylakoid membranes where photosystem II occurs (PSII). We investigated the chlorophyll fluorescence () of PSII, photosynthetic pigments, membrane damage, and the activity of protective antioxidants in drought-tolerant and -sensitive varieties of C3 sunflower and C4 maize grown at 20/25 and 30/35 °C.

Microbiomes in Soils Exposed to Naturally High Concentrations of CO (Bossoleto Mofette Tuscany, Italy).

Direct and indirect effects of extremely high geogenic CO levels, commonly occurring in volcanic and hydrothermal environments, on biogeochemical processes in soil are poorly understood. This study investigated a sinkhole in Italy where long-term emissions of thermometamorphic-derived CO are associated with accumulation of carbon in the topsoil and removal of inorganic carbon in low pH environments at the bottom of the sinkhole. The comparison between interstitial soil gasses and those collected in an adjacent bubbling pool and the analysis of the carbon isotopic composition of CO and CH clearly indicated the occurrence of CH oxidation and negligible methanogenesis in soils at the bottom of the sinkhole.

Publisher Correction: Impaired photosynthesis and increased leaf construction costs may induce floral stress during episodes of global warming over macroevolutionary timescales.

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Impaired photosynthesis and increased leaf construction costs may induce floral stress during episodes of global warming over macroevolutionary timescales.

Global warming events have coincided with turnover of plant species at intervals in Earth history. As mean global temperatures rise, the number, frequency and duration of heat-waves will increase. Ginkgo biloba was grown under controlled climatic conditions at two different day/night temperature regimes (25/20 °C and 35/30 °C) to investigate the impact of heat stress.

Testing decontaminated sediments as a substrate for ornamentals in field nursery plantations.

When canals and harbours are dredged, huge amount of polluted sediments has to be stocked and transported to the landfill with incredibly high costs of management. Among the remediation techniques for the reclamation of polluted sediments and soils, phytoremediation represents a sustainable and effective technique though still not fully promoted or commercialized. In this study we have tested the suitability for plant nursing of a substrate resulting from sediments dredged from a canal and treated with phytoremediation.

Impaired Stomatal Control Is Associated with Reduced Photosynthetic Physiology in Crop Species Grown at Elevated [CO].

Physiological control of stomatal conductance () permits plants to balance CO-uptake for photosynthesis () against water-loss, so optimizing water use efficiency (WUE). An increase in the atmospheric concentration of carbon dioxide ([CO]) will result in a stimulation of and reduction of in many plants, enhancing carbon gain while reducing water-loss. It has also been hypothesized that the increase in WUE associated with lower at elevated [CO] would reduce the negative impacts of drought on many crops.

Adaptation to high temperature mitigates the impact of water deficit during combined heat and drought stress in C3 sunflower and C4 maize varieties with contrasting drought tolerance.

Heat and drought stress frequently occur together, however, their impact on plant growth and photosynthesis (P ) is unclear. The frequency, duration and severity of heat and drought stress events are predicted to increase in the future, having severe implications for agricultural productivity and food security. To assess the impact on plant gas exchange, physiology and morphology we grew drought tolerant and sensitive varieties of C3 sunflower (Helianthus annuus) and C4 maize (Zea mays) under conditions of elevated temperature for 4 weeks prior to the imposition of water deficit.

The impact of built-up surfaces on land surface temperatures in Italian urban areas.

Urban areas are characterized by the very high degree of soil sealing and continuous built-up areas: Italy is one of the European countries with the highest artificial land cover rate, which causes a substantial spatial variation in the land surface temperature (LST), modifying the urban microclimate and contributing to the urban heat island effect. Nevertheless, quantitative data regarding the contribution of different densities of built-up surfaces in determining urban spatial LST changes is currently lacking in Italy. This study, which aimed to provide clear and quantitative city-specific information on annual and seasonal spatial LST modifications resulting from increased urban built-up coverage, was conducted generally throughout the whole year, and specifically in two different periods (cool/cold and warm/hot periods).

Coordination of stomatal physiological behavior and morphology with carbon dioxide determines stomatal control.

Premise Of The Study: Stomatal control is determined by the ability to alter stomatal aperture and/or the number of stomata on the surface of new leaves in response to growth conditions. The development of stomatal control mechanisms to the concentration of CO₂within the atmosphere ([CO₂]) is fundamental to our understanding of plant evolutionary history and the prediction of gas exchange responses to future [CO₂].

Methods: In a controlled environment, fern and angiosperm species were grown in atmospheres of ambient (400 ppm) and elevated (2000 ppm) [CO₂].

Joint control of terrestrial gross primary productivity by plant phenology and physiology.

Terrestrial gross primary productivity (GPP) varies greatly over time and space. A better understanding of this variability is necessary for more accurate predictions of the future climate-carbon cycle feedback. Recent studies have suggested that variability in GPP is driven by a broad range of biotic and abiotic factors operating mainly through changes in vegetation phenology and physiological processes.

Carbon dioxide fertilisation and supressed respiration induce enhanced spring biomass production in a mixed species temperate meadow exposed to moderate carbon dioxide enrichment.

The rising concentration of carbon dioxide in the atmosphere ([CO2]) has a direct effect on terrestrial vegetation through shifts in the rates of photosynthetic carbon uptake and transpirational water-loss. Free Air CO2 Enrichment (FACE) experiments aim to predict the likely responses of plants to increased [CO2] under normal climatic conditions. The Giessen FACE system operates a lower [CO2] enrichment regime (480μmolmol-1) than standard FACE (550-600μmolmol-1), permitting the analysis of a mixed species temperate meadow under a [CO2] level equivalent to that predicted in 25-30 years.

Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms.

• It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms.

Stomatal index responses of Agrostis canina to CO2 and sulphur dioxide: implications for palaeo-[CO2] using the stomatal proxy.

• Stomatal index values of fossil plants are widely used in reconstructing palaeo-[CO(2)]. This depends upon the assumption that the stomatal index is determined by the atmospheric concentration of CO(2) ([CO(2)]). This study investigates whether fumigation with, and resistance to, sulphur dioxide (SO(2)) induces a reduction in the stomatal index that may affect stomatal reconstructions of palaeo-[CO(2)] coinciding with episodes of global-scale volcanism.

Soil Respiration in European Grasslands in Relation to Climate and Assimilate Supply.

Soil respiration constitutes the second largest flux of carbon (C) between terrestrial ecosystems and the atmosphere. This study provides a synthesis of soil respiration (R(s)) in 20 European grasslands across a climatic transect, including ten meadows, eight pastures and two unmanaged grasslands. Maximum rates of R(s) (R(s(max) )), R(s) at a reference soil temperature (10°C; R(s(10) )) and annual R(s) (estimated for 13 sites) ranged from 1.

Leaf traits and tree rings suggest different water-use and carbon assimilation strategies by two co-occurring Quercus species in a Mediterranean mixed-forest stand in Tuscany, Italy.

We compared the water-use characteristics of co-occurring mature Quercus cerris L. and Quercus pubescens Willd. trees growing in resource-limited (mainly water) hilly habitats in Tuscany, Italy.

Physiological and morphological responses of grassland species to elevated atmospheric CO2 concentrations in FACE-systems and natural CO2 springs.

Stomatal density, leaf conductance and water relations can be affected by an increase in the concentration of atmospheric CO, and thus affect plant productivity. However, there is uncertainty about the effects of elevated CO on stomatal behaviour, water relations and plant productivity, owing to the lack of long-term experiments in representative natural ecosystems. In this work, variations in stomatal density and index, leaf water relations and plant biomass of semi-natural grassland communities were analysed under field conditions by comparing plants in three different experimental set-ups (natural CO springs, plastic tunnels and mini-FACE systems).

Influence of increased atmospheric CO(2) concentration on quality of plant material and litter decomposition.

Nitrogen (N) and lignin concentrations in plant tissues and litter of plants grown in greenhouses or open-top chambers in elevated atmospheric CO(2) concentration were compared with those of plants grown in ambient air in short-term studies. We also compared the N concentration of plant material of Quercus ilex L. and Q.

Seasonal embolism and xylem vulnerability in deciduous and evergreen Mediterranean trees influenced by proximity to a carbon dioxide spring.

We investigated how proximity to natural CO(2) springs affected the seasonal patterns of xylem embolism in Quercus ilex L., Quercus pubescens Willd., Fraxinus ornus L.

Water relations, stomatal response and transpiration of Quercus pubescens trees during summer in a Mediterranean carbon dioxide spring.

Variations in water relations and stomatal response of Quercus pubescens Willd. were analyzed under Mediterranean field conditions during two consecutive summers (1993 and 1994) at two locations characterized by different atmospheric CO(2) concentrations because of the presence at one of them of a CO(2) spring. Trees at the CO(2) spring site have been growing for generations in elevated atmospheric CO(2) concentrations.

Seasonal changes in tissue elasticity and water transport efficiency in three co-occurring Mediterranean shrubs under natural long-term CO2 enrichment.

Seasonal changes in hydraulic properties and tissue elasticity were evaluated in Erica arborea L., Myrtuscommunis L. and Juniperus communis L.