Sur l'organisation biochimique es phytocénoses en milieu dulçaquicole médio- européen
2001
In an overall study of the biochemical organization of phytocenoses, an analysis of the
organic components (carbohydrates, tanins, lignin) and mineral components (biogenic metals
and metalloids) of 36 land and aquatic vegetal species was conducted in the Dombes (Ain,
France), a region of fresh-water ponds in the deciduous biome. The multivariate analysis of
the phytochemical data collected showed a tripolar organization based on phenolic
pool/mineral pool opposition (land plants versus aquatic plants) and cellulose/lignin
opposition (emerging aquatic plants versus floating plants).
Although links were detected between the biochemical profiles of the plants and
phytosociological divisions or land-encroachment process, the discussion of the results is
complicated by the fact that most of the land plants considered are lignous dicotyledons
whereas the emerging aquatic species are primarily herbaceous monocotyledons. However, it
may be stated that the parietal macromolecules of the floating species (dicotyledons or
monocotyledons) are more dependent upon the environment that on the systematics and that
lignin dominates cellulose in all the species, as for land plants.
As far as the mineral components are concemed, the aquatic plants generally show more
abundant minerais than species on the land (1.5 to 2 fold difference). Potassium content is
generally 2.9 % in floating aquatic plants compared with 2.2 % in emerging plants and only
1.2 % in land plants. This element is therefore considerably concentrated with respect to the
ambiant water (by a factor of more than 1 000) whereas calcium is only wealdy concentrated
(by a factor of less than 100). Floating plants contain more biogenic metalloids than both
emerging aquatic species and land species: 3.7 % compared with 2.4 ± 0.4 % for nitrogen,
0.46 %o compared to 0.24 %o for phosphorus.
These results confirm the presence of a biochemical organization of plant communities
based on phenols, parietal macromolecules and biogenic elements. However, since the
fresh-water medium studied is highly heterogeneous (from ftoating aquatic associations to
meso-hygrophylic climacic oak forest), each of the three sub-groups needs to be taken into
consideration to gain a full understanding of this plant community. A discussion is initiated
to extend these observations and confirm the existence of a phytochemical organization of
phytocenoses, in relation with the notion of "phytochemical tactics" and the allocation of
trophic resources.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
0
References
0
Citations
NaN
KQI