Herb stage - xerarch, Biology

Herb Stage - Xerarch

The Soil-forming and soil-holding reactions of the mosses are so pronounced that the seeds of various xerophytic herbs, especially short-lived annuals: are soon able to germinate and grow. The plants mature, although the first generations, because of the drought and sterility of the soil, may make only a stunted growth. Their roots continue the process of corroding the rock, and each year the humus from their decaying remains enriches the soil. Gradually, biennials and perennials begin to invade the area and with the habitat becoming more and more favourable, their numbers also increase.

The processes of rock disintegration and humus and nutrient accumulations are greatly increased, as the tangled network of roots increases and the soil becomes shaded. Evaporation and temperature extremes are decreased, humidity is slightly increased, and drought periods are shortened. The bacterial, fungal and animal populations of the soil increase and conditions gradually become less xeric. Up to now, some xerophilous, shallow rooted grasses like Aristida, Festuca and Poa were growing. As the conditions improve, then some drought-enduring species like Potentilla, Solidago and many others invade the area. As a result of growth of the herbs, the smaller plants like mosses and lichens do not get enough light. So these conditions are detrimental for their growth, they gradually start perishing.

Posted Date: 1/21/2013 12:23:30 AM | Location : United States







Related Discussions:- Herb stage - xerarch, Assignment Help, Ask Question on Herb stage - xerarch, Get Answer, Expert's Help, Herb stage - xerarch Discussions

Write discussion on Herb stage - xerarch
Your posts are moderated
Related Questions
Inter specific Incompatibility This type of incompatibility is characterized by the prevention of fusion of gametes between members of different species. The incompatibility

Explain the Transport of Amino Acids? More than one transport or carrier system functions in the absorption of amino acids. The active carrier system for neutral amino acids sh

Explain the Indications for neuropsychological screening Nature of referral question warrants it. Situational explanation for changes in emotions or cognitive functioni

Structure of HIV HIV is a spherical enveloped virus of about 90-120 nm diameter .In nucleocapsid is icosahedral. Its genome consists of a single stranded RNA filament segmented

Explain Iron Uptake by Cells? Iron participates in a large number of biochemical reactions. However, for iron to perform any function, it first needs to be taken up by the cell

What is Hemorrhage Mild to moderate capillary ooze can readily be controlled by pressure packing. A more severe venous or, in rarer instances, an arterial bleed may require cl

The breakdown of ATP releases energy, which is utilized by other reactions that require energy. Identify other examples where inventions have utilized a similar principle, where en

BON E - Bone is the hardest tissue in the body and supports various organs. The inorganic salts present in the matrix are calcium phosphate, calcium carbonate, calci

how many species of protozoan?

Results: The risk of isolated aortic valve replacement is 3-4 per cent. The long term survival for 5, 10 and 15years is 75 per cent, 60 per cent and 40 per cent respectively. The