Crustose lichen stage - xerarch, Biology

Assignment Help:

Crustose Lichen Stage - Xerarch

On bare rocks, conditions are inhospitable for life, as there is extreme deficiency of water and nutrients, great exposure to sun, and extremes of temperature. Crustose lichens alone are usually able to grow in such situations. Some examples of these pioneering species are, Rhizocarpon, Rhinodina, Lecidea and Lecanora. These plants flourish during periods of wet weather and remain in a state of desiccation for very long periods during drought. During the wet weather they rapidly absorb moisture by their sponge-like action. Mineral nutrients are obtained by the secretion of carbon dioxide which, with water forms a weak acid that slowly eats into the rock into which the rhizoids sometimes penetrate for a distance of several millimetres.

Nitrogen is brought by rain or by wind-blown dust. Thus all the life requirements of this simple, crust-like species is met with. Thus, lichens help corrode and decompose the rock, supplementing the other forces of weathering. And by mixing the rock particles with their own remains, make conditions favourable for - growth of other organisms. Thus, a thin layer of soil is formed. The rapidity with which a small amount of soil is formed is controlled largely by the nature of the rock and by the climate. On quartzite or basalt rocks in a dry climate, the crustose-lichen stage might persist for hundreds of years. But on limestone or sandstone in a moist climate, sufficient changes permit the invasion of foliose lichens, and all this may occur within a life time.


Related Discussions:- Crustose lichen stage - xerarch

Explain strengthening the public health measures - anaemia, Explain Strengt...

Explain Strengthening the public health measures? Parasitic infestations and protozoal infections cause iron deficiency through loss of blood or destruction of red blood cells.

Contractile vacuoles - excretion, Normal 0 false false fals...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Kuch, how vagina is inserted in cock

how vagina is inserted in cock

Explain xylose isomeras, Explain xylose isomeras A mixture of glucose ...

Explain xylose isomeras A mixture of glucose and fructose, is produced from sucrose by the action of yeast invertase (β-fructofuranosidase), an enzyme which can only be extrac

Does peptide bonds are amide linkages, Which of the following statements ab...

Which of the following statements about peptide bonds are true? Peptide bonds are amide linkages Peptide bonds form from nucleophillic attack by an electron pair on an alpha-

Are the arterial pulsations normal, Are the arterial pulsations normal? ...

Are the arterial pulsations normal? Is the pulse volume normal or increased? Is there a discrepancy of pulsation in any of the four extremities? A careful evaluation of pulsati

Heat production and respiratory quotient for foodstuff types, Heat producti...

Heat production and respiratory quotient for foodstuff types The heat produced during the metabolic activities of the body helps in maintaining the body temperature. Generally

Explain the aseptic technique - sub culturing, Explain the Aseptic Techniqu...

Explain the Aseptic Technique - Sub Culturing? Aseptic technique is a series of procedures used to prevent contamination of cultures and sterile culture media. It is one of the

What will phenotypical feature actually manifested depend, For an individua...

For an individual having a genotype formed of two different alleles that condition different varieties of the same phenotypical trait, upon what will the phenotypical feature actua

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd