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Summary [ABSTRACT FROM AUTHOR]

Summary [ABSTRACT FROM AUTHOR]

The representation of root activity in models is here confined to considerations of applications assessing the impacts of changes in climate or atmospheric [CO2]. Approaches to modelling roots can be classified into four major types: models in which roots are not considered, models in which there is an interplay between only selected above-ground and below-ground processes, models in which growth allocation to all parts of the plants depends on the availability and matching of the capture of external resources, and models with explicit treatments of root growth, architecture and resource capture. All models seem effective in describing the major root activities of water and nutrient uptake, because these processes are highly correlated, particularly at large scales and with slow or equilibrium dynamics. Allocation models can be effective in providing a deeper, perhaps contrary, understanding of the dynamic underpinning to observations made only above ground. The complex and explicit treatment of roots can be achieved only in small-scale highly studied systems because of the requirements for many initialized variables to run the models. [ABSTRACT FROM AUTHOR]

The growth rates of Dactylis glomerata L. and phleum bertolonii D.C., which are essentially lowland species in Britain, show a large response to an increase in day temperature from 10 to 20 °C, while those of Sesleria albicans Kit. which occurs from sea-level to 900 m, and Phleum alpinum L. (600 to 1200 m) show little response. These differences can be attributed to the greater leaf-area ratio, and to the increased rates of both leaf-initiation and leaf-expansion of the lowland species at higher temperatures. Net assimilation rates are scarcely affected by temperature. The differences are therefore due to morphogenetic effects and not to differences in the rates of physiological processes. [ABSTRACT FROM AUTHOR]

The use of the light-induced absorbance change at 820 nm (ΔA 820) to monitor the oxidation and reduction of P-700 in irradiated leaves is examined. Results obtained from leaves irradiated with a range of wavelengths of light, poisoned with DCMU, or lacking PS I, are consistent with the proposition that the light-induced ΔA 820 can be used to monitor P-700 oxidation in leaves. [ABSTRACT FROM AUTHOR]

The author offers information on the topics discussed in the journal "Tansley Reviews." He states that the journal addresses a wide range of organizational scales within each process, from plant organelles to ecosystems. He also cites several physiological studies of plants, including evolution and development.

The article focuses on a study addressing the structure and physiology of leaf. The result of the study shows that a climatic reconstructions using oxygen isotopes in tree-ring cellulose with require reanalysis that takes into account the effect of leaf temperature and relatively humidity on the 18 O:16O ratio. It further notes that leaf structure and physiology show rather differences globally due to variations in temperature of the environment. Looking at the result of the study, the author suggests the need for greater emphasis on understanding how the canopy responds to climate change, and to global warming.