C - Lublin

As the organisms reach the generative phase, the necrobolism of turning
biomass into the necromass begins. It consists of two subprocesses: the necrosis
itself and return of vital substances into still functioning organs, first of all
generative ones (flowers, fruits, seeds).The mature organisms provide generation of
populations. Once the generative phase is completed, the biomass used up its life
resource dies, turning into the necromass.
Since the “landing” of necromass, the catabolism starts: dissimilation of dead
organic matter into simple mineral elements. It also comprises two subprocesses:
mineralization and humification.
The sequence of dissimilation of organic matter depends upon the strength of
chemical bonds, composition and activity of heterotrophic soil biota. Initially
simple compounds are mineralized: sugars, proteins, amino acids, then more
complicated ones and finally stable substances like lignin, chitin, and bone tissues.
As a result of mineralization of simple compounds mineral gases (CO 2 , methane,
ammonium etc.) are formed. More complicated compounds with higher ash content
form except gases, mineral salts or free radicals. Gases are absorbed by the plant
leaves or diffused in the atmosphere.
A great part of mineral elements is absorbed by the root system of plants. The
elements not required by phytocenosis interact with free radicals, forming soil
humus. The other elements migrate with water solutions on soil profile and relief
incline and the ecosystem losses them. Humus, as a product of second synthesis,
entering into the composition of necromass, is also the subject to mineralization,
but it is mineralized more slowly and with release of much more salts than gases.
Humines are the most resistant fraction of organic matter. The process of their
complete mineralization lasts for decades and centuries. Mineral colloids with
small amount of salts of rare elements are the products of mineralization. They
completely remain in the soil, enriching the reserve of minerals and falling out
from biological turnover.
In natural ecosystem the losses of substances are minimal. Usually the
elements not demanded for phytocenosis and incorporated into humus are lost. The
losses increase sharply at changing external conditions, which stimulate the
processes of adaptation. In this connection, to endure in new conditions the
organisms change their function and the ecosystem - its structure. The change of
species composition disturbs the normal rhythm of substances turnover, creating
the conditions for removing the chemical elements from the ecosystem.
Catastrophic losses of mineral elements occurs at fires and invasion of
entomological pests (locust, silkworm), when biomass is mineralized almost
completely, and anabolism is blocked. The weeds become rescues of ‘gold supply’
of the mineral elements. They can increase their own mass by hundred and
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