Terrestrial habitats

There is considerable interest in the removal of contaminants from the sites of former gas-lilling stations. The surrounding soil is contaminated not only with fuel hydrocarbon residues, but also with alkyl lead compounds that were previously used as gasoline additives. It has been shown 

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The evolution of structures and mechanisms in plants to regulate water fluxes down these steep thermodynamic gradients and yet maintain the cellular conditions for biochemical activity was a major factor in the colonisation of the terrestrial habitat. Paradoxically, therefore, some water stress is completely normal , though some plants are better than others at accommodating large deviations. 

Hitherto, the normal source of collections has been from terrestrial habitats. However, marine bioprospecting represents a vast untapped area that is likely to be intensified. Exhibit 11.1 describes the diversity and hfe forms in this habitat. 

It may also be possible to hypothesize that aquatics will be of less interest in screening programs as aquatic environments do not expose plants to as great a diversity of pathogens and predators. It may be that terrestrial habitats present a more competitive situation that favors selection of a greater accumulation of diverse secondary metabolites with specific bioactivities, the exact kinds of molecules likely to be of interest in pharmaceutical screens. 

In 13 strains of cyanobacteria (from mostly freshwater and terrestrial habitats) grown under artificial UV (X,ma - 320 nm), MAA concentrations increase under UV exposure relative to controls under PAR alone (Table 15.5).132 A similar response occurs for MAAs in the sheath matrix of Nostoc commune.135,168 Additionally, the increased synthesis of extracellular MAAs is accompanied by an increased production of glycan that thickens the cellular sheath.168 In the cyanobacterium Chlorogloeopsis sp UV irradiation is not an obligate requirement for MAA synthesis.56 MAA synthesis in this species is not constitutive but is induced by UVB or increased osmotic stress (see also Section II.A. 10). 

Crustaceans are good to eat, and many species of vertebrates, including whales, fish, and people, include them in their diets. They are important links in the food chains in many different marine and terrestrial habitats. 

Dighton, I. (1997). Nutrient cycling by saprotrophic fungi in terrestrial habitats. In The... 

In terrestrial habitats the symbiotic fixation of nitrogen by Rhizobia accounts for the largest contribution of combined nitrogen. For example, Rhizobia associated with an alfalfa field may fix up to 300 kg N/ha/year, compared with a rate of 0.5-2.5 kg N/ha/year for free-living Azotobacter species. 

Herbaceous plants are good indicators of the current status of ecological conditions in a specific habitat. Because of their relatively short life cycles and their fast growth they occupy a wide range, from purely aquatic to terrestrial habitats in the floodplains. Establishing patterns of distribution of herbaceous vegetation in floodplains is... 

Staley, S. T., and Konopka, A. (1985). Measurement of in situ activities of nonphotosynthetic microoganisms in aquatic and terrestrial habitats. Annu. Rev. Microbiol. 39, 321—346. 

McNaughton S. L, Oesterheld M., Frank D. A., and Williams K. J. (1989) Ecosystem-level patterns of primary productivity and herbivory in terrestrial habitats. Nature 341, 142-144. 

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