It is known, that the trees, when grow in the forest, carried out of the soil more than 60 chemical elements. Among them, such as Сalcium, which prevents the acidification of the soil. In contrast to agricultural systems, forest systems are not fertilized. Therefore, roots secrete acids, which destroying soil minerals and thereby forming mineral nutrients. It is also known, that trees, unlike herbs, used NH4+, highlighting equivalent ion H+ to soil. Ukrainian scientist prof. Ivan Gogolev showed, that during 60 years coniferous forest per 1 hectare allocates acids, the number of which is equivalent to 12 tons of concentrated sulfuric acid. Can we consider this trees of acid aggressors?
Yes trees can change the soil chemistry . In addition to what you said, some forest tree can deposit chemicals through the Allelopathy mechanism.
Yes Zenon , this is a very valid point , we have observed , there is hardly any vegetation comes out within rhizosphere zone of conifers., because of such scale of acidification of soil . But , this is a specific case . There are other forest species do wonders to the cause of ecosystem through serving better carbon sinks.
Although trees remove nutrients from soil, much of these nutrients are returned to the soil with litter. Besides, the trees, through their root system, pump nutrients from deep soil areas and then return them to the soil surface. Soil depletion and acidification caused by nutrient uptake by trees can be balanced by weathering of primary minerals (particularly if trees grow slowly), which is favoured in the rhizosphere. So climax forests maintain a steady soil pH as long as they are not disturbed by man.
Some very valid points. After all , to maintain a global ecological balance , we need to maintain atleast 5 billion ha of grassland and another 4 billion ha of forestland, besides both together serving as the biggest carbon sink ..
Yes Anoop, some plants, due to the mechanism of rhizosphere, provide additional large amount of CO2 in the photosynthesis zone. In particular, the specific feature of the biological carbon cycle wetland ecosystem is the presence of the "inner cycle of C", as a result of which is formed by more 60% of the net primary production.
Yes it is true that trees are known to modify soil pH. Underneath the conifers, the soil remained acid, and in some cases became even more acid. Underneath the broad leaves, the soil generally became more alkaline. It depends upon the amount of calcium in the leaves of the tree – the more calcium, the higher the soil pH (alkaline). The tree with the most calcium-rich foliage, and which also produced the biggest rise in soil pH. please read following link:
http://www.telegraph.co.uk/gardening/plants/trees/10633984/Do-conifers-make-soil-more-acid.html
You can check the BA African Networks for more information
http://afn.bibalex.org/GeneralPortal.aspx
yes sir...due to continuous deposition of leaves and release of Hydrogen ions and decrease in base saturation.
The OC rich forest soils of India have less Al-saturation in surface horizons due to the downward movement of Al as organo-metal complexes or chelates, but have higher base saturation than the sub-surface horizons due to addition of alkaline and alkaline metal cations through litter fall , and there is no desilication and transformation of kaolin to gibbsite. In view of the contemporary pedogenesis, it is difficult to reconcile that such acid soils would ever be weathered to reach the Oxisols stage with time. Such OC rich acid soils with dominant kaolin mineral (based on their clay CEC > 24 cmol(p+)kg-1 determined by BaCl2-TEA for total acidity plus bases by NH4OAc,pH7 method) do respond to management interventions and support luxuriant forest vegetation, horticultural, cereal crops, tea, coffee and spices. Therefore, it would not be prudent to class these acid soils as chemically degraded soils. At present, the extent of degradation (soil loss and soil acidity) of forest soils (Ultisols, Alfisols, Mollisols and Inceptisols with clay enriched B horizons )is not at all in an alarming stage. The above discussion clearly highlights the importance of the basic pedogenic processes and determination of the mineralogy class while deciding the extent of chemical degradation of such soils. The attached pdf may be of some help.
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