Forest and savanna are the two dominant vegetation types of the tropical regions with very few tree species common to both. At a broad scale, it has long been recognised that the distributions of these two biomes are principally governed by precipitation and its seasonality, but with soil physical and chemical properties also potentially important. For tree species drawn from a range of forest ...

Photosynthetic capacity is one of the most sensitive parameters in vegetation models and its relationship to leaf nitrogen content links the carbon and nitrogen cycles. Process understanding for reliably predicting photosynthetic capacity is still missing. To advance this understanding we have tested across C(3) plant species the coordination hypothesis, which assumes nitrogen allocation to pho...

In field experiments photoinhibition of photosynthesis'in the intertidal brown alga Fucus serratus was investigated by means of both fluorescence and oxygen measurements. Samples were taken from thalli floating just below the water surface. Dunng falling tides the ratio variable fluorescence/maxlrnum fluorescence (FJF,) decreased with increasing photon fluence rates. As during rising tides only...

The aim of this work was to characterize the respiratory metabolism of the greening cotyledons of cucumber (Cucumis sativus L.) during early seedling growth and to investigate how this is integrated with changes in mitochondrial biogenesis and function. In light-grown cotyledons, lipid mobilization extended from germination to 6 days postimbibition, reaching a maximum at 3 to 4 days postimbibit...

Pseudovivipary is an asexual reproductive strategy exhibited by some arctic/alpine grasses in which leafy plantlets are produced in place of seeds, with genetic conservation an advantage for stress tolerators in these nutrient-poor habitats. Photosynthetic metabolism and the development of this reproductive system were investigated under varying nutrient availability and predicted future CO(2) ...

Introduction The rate and extent of leaf thickness and area Leaves which develop at elevated CO2 concentrations are development are important determinants of whole often thicker than those on ambient 2 plants. In a plant photosynthetic capacity. The interactive effects study of four Populus clones, Radoglou and Jarvis (1990) of photon flux density (PFD), nitrogen supply and CO 2 found increases...

From January 1999 to May 2001, we investigated seasonal variations in the photosynthetic capacity of Taiwan spruce (Picea morrisonicola Hay.) growing in the subalpine region of subtropical Taiwan (23 degrees 29' N, 120 degrees 53' E, 2600 m a.s.l.). Photosynthetic capacity (near light-saturated net photosynthetic rate, Pnsat, chlorophyll fluorescence (Fv/Fm) and soluble protein concentration of...

The rate of oxygen evolution/consumption, in vivo electron transport activity, overall photosynthetic capacity and accumulation of the chloroplast 30 kDa heat shock proteins were studied after treatment of intact barley seedlings at 40oC for 3 hours either in presence of low white light (100 μmol m–2.s–1) or in the dark. High temperature impact in the dark resulted in lowering of water-splittin...

Seedlings of two late-successional tropical rainforest tree species, Tetragastris panamensis (Engler) O. Kuntze and Calophyllum longifolium (Willd.), were field grown for 3-4 months at an open site near Panama City (9 degrees N), Panama, under plastic films that either transmitted or excluded most solar UV-B radiation. Experiments were designed to test whether leaves developing under bright sun...

The availability of dissolved inorganic carbon (DIC) may have a considerable impact on species competition in phytoplankton communities. The growth, photosynthetic characteristics and competition of three strains, the toxic Microcystis aeruginosa FACHB 912, nontoxic M. aeruginosa FACHB 469 and Chlamydomonas microsphaera FACHB 52, were investigated under two different DIC concentrations (0.365 a...