The word nécromasse indicates the mass of Organic matter dead present in a piece, a volume or a ecosystem donné.
The concept of nécromasse returns to that of biomass (alive organic matter).
Nuances in the definitions
- For some, nécromasse it limits itself strictly to the corpses (animal, vegetable, fungic and microbial).
- Of others also includes in nécromasse all the waste produced by the living beings, if they consist of organic matter:
- the oxygen produced by the plants or CO expired by the animals are excreted, but they are not organic matter. They are thus not entered in nécromasse.
- Certains authors distinguishes particular a category known as subnécromasse which relates to the almost dead trees (ex: tree dying man) in addition to really dead wood but not broken up (nécromasse).
Nécromasse and grounds
Except in the deserts and sometimes in the tropical zones, most of the original ground makes up of nécromasse and/or of the décomposition.Ces last years the Deadwood is the product took an particular importance in forest ecology. According to the studies led in the forests known as primary or little anthropized, or in the model Forest of Fundy;
- - In a natural moderate forest not exploited: 30% of wood present died;
- - In tropical forest, because of heat and moisture, the dead matter is recycled much more quickly, and the carbon moindrement stored in the grounds.
- - In the cold forests (close to the poles or in altitude), the decomposition of nécromasse can be very slowed down (congelation in permafrost, peat formation, or decomposition slowed down by the cold.
- - the black grounds of meadow accumulated organic matter resulting from the decomposition of the plants and excrements from the herbivores and carnivores.
- - the peat bogs consituent of enormous quantities of nécromasse accumulated breaking up badly because of the lack of oxygen and sometimes of the acidity of the medium (peat bogs with sphaignes by ex).
- - In tropical forest, because of heat and moisture, the dead matter is recycled much more quickly, and the carbon moindrement stored in the grounds.
Nécromasse and climate
Oil, the natural gas, and coal, as of many rocks result from a slow process of degradation of nécromasse at the time which carbon was sequestered, stabilized and hidden. The cycle of the organic matter is included in the cycle of the carbon which one now knows the importance for the rétrocontrôle climate by the alive one. With climate warming, part of nécromasse can be broken up by producing CO and methane (CH) or burn.
Cycles
One can speak about Flux of nécromasse which can be studied for example per units of volume (at sea) of surface (on the ground) or by soil horizons, in particular thanks to tracers isotopic natural or artificial, within a compartment of the ecosystems, or between several compartments.Thus the animal corpses are generally quickly eaten by the necrophagous ones or of the décomposeurs. Thus marine organizations can nourish rains of excrements and corpses " tombant" surface. Nécromasse animal and vegetable nourishes successive communities décomposeurs, associating on the grounds emerged narrowly of the bacteria and mushrooms and the bacteria under the seas.
One can also speak about flow of energy and Entropie/Néguentropie. Nécromasse contains energy; it is the first fossil form of the solar energy accumulated by the plant then by the organizations which nourish themselves some. This energy is used and to some extent reinjected in the ecosystem by the necrophagous one and the décomposeurs.
In the forests of moderate or cold zones, the accumulation of coarse woody remains died on the ground follows a theoretical evolution parallel with that of the air woody biomass, but with a delay in time (from 90 to 150 years according to the type of forest). Exceptional diseases, storms or forest fires can nevertheless upset this rule;
Nécromasse and biodiversity
The diversity of the species and the animal, fungic and vegetable communities is related to the offer in substrates varied and complex, which is mainly ascribable to nécromasse vegetable (and woody in forest). A large dead tree can remain, for several centuries a support for hundreds of species. In moderated zone, nécromasse it woody (deadwood) when it is high, AND if it is associated with a biomass and with a specific diversity high (i.e much of different animal species and vegetable) is an indicator of seniority of the forest ecosystem. In moderated zone, the absence of nécromasse woody indicates very exploited or overexploited forests. This is why the presence of nécromasse, and in particular of old men and large deadwood is an indicator retained for the forest ecocertification FSC (Forest Stewardship Council) , and recommended for the PEFC.
" Nothing more alive than wood mort"
A world report/ratio of the Funds of nature (WWF) alerted in 2004 on the fact that nearly a third of the species (animal, vegetable, fungic.) depend on nécromasse and in particular deadwood in forest. 20-25% on the forest species would depend directly on the only deadwood
(Elton, 1966; Stokland and Al, 2004). However, of many foresters clean their forest as well as the dead rate of trees is not there even any more of one per ha. (the minimal engagement of the ONF in France). Too much to eliminate the large deadwood and the senescent trees threatens directly of many species essential to the good performance of the ecosystem foresters (ex: peaks, owls, owls, bats, squirrels and a multitude of insects and mushrooms which in normal weather produce normally but slowly the invaluable forest ground).
An integral forest reserve will often contain 20 times more nécromassse that a managed forest, while abounding in life. The deadwood attacked by mushrooms and cover of foam is not very sensitive to the fires and it produces a ground which retains water well best.
(see conference of Chambéry on the deadwood and with cavities).
One second life for the dead animals
In the same way the corpses the large ones and average animals disappear from our environment, probably not without ecological consequences.
The large carnivores and large vultures disappeared from many countries, but some experiments consisting in leaving the corpses of large animals of natural parks or reserves on the spot (except if it are in water) showed that a corpse of cow could be reduced to the state of a skeleton cleaned well in 12 days in the Netherlands for example, in a rich and complex environment.
Indicators
In continental and moderate zone the biomass of the ground in Worms of ground and Champignon S is regarded as a good indicator of nécromasse ground.Nécromasse is itself a Bio-indicateur.
Internal bonds
External bonds
| Random links: | Canton of Lapalisse | Furan | Statute of the cities in the United Kingdom | T 13 AL and ex-Prussia | Chaouf (chrif village oueld) |