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Biological Soil Crusts, Plant Functional Groups, and Soil Parameters in Arid Areas of Iran

Bashtian M. H., Sepehr A., Farzam M., Bahreini M.

Polish Journal of Ecology

2018

Vol. 66, nr 4

337--351

Biological soil crusts (BSCs) have a vital role regarding vegetation and soil development in arid and semi-arid areas in the world, and apparently in Iran, where they comprise more than 85% of the land. In this research, the relationship between BSCs and plant functional groups, considering soil parameters along an arid alluvial fan located in Khorasan Razavi province in northeastern Iran, was examined. The sampling carried out in summer, systematically from apex towards base part of alluvial fan, using a 0.25 m2 quadrat over a 5-cm thick soil surface. Surface levels were classified into three categories: apex, middle, and base. At each level, 16 samples were taken; in total 48 samples were collected along the alluvial fan from the apex point to the base district. The results showed a strong relationship between BSCs and the soil surface features, and a weak correlation between the plant functional group and soil parameters. BSCs indicated an ecological evolution from apex to the base geomorphic level by soil development; so that BSCs are more developed on the base of alluvial fan, but their diversity is reduced.

Podstawowe techniki eksperymentalne spektroskopii NMR w fazie ciekłej

Koźmiński W.

Wiadomości Chemiczne

2005

[Z] 59, 1-2

107--120

General overview of most important NMR techniques and applications for organic and bioorganic molecules in liquids is given. The sensitivity of NMR experiments is discussed with regard to nuclear properties, Bo field, applied method of excitation and detection, and finally concentration. In the next chapter the principles and consequences of quadrature detection are discussed. The most important techniques of quadrature detection in directly and indirectly detected domains are exemplified. In the next point the principles, advantages and disadvantages of coherence selection techniques via phase cycling and Pulsed Field Gradients are indicated and compared with respect to various applications. In the last part of present article the most important homo- (COSY, TOCSY, NOESY, and ROESY) and heteronuclear (HSQC, HMQC/HMBC) techniques used in NMR investigations in liquids are briefly reviewed. The characteristic features and experimental problems of these methods are discussed with respect to usual applications in chemistry and biochemistry.