Geoscience Reference
In-Depth Information
oxygen, organic matter tends to accumulate as
peat, muck, or organic-rich mineral layers. Color
is among the best indicators for the status of
iron and organic matter in hydric soils.
Organic-rich soils (peat and muck) are typi-
cally oligotrophic and acidic, which limit plant
diversity and productivity. Mineral hydric
soils, in contrast, are mesotrophic to eutrophic
and less acidic to basic. These conditions
support greater l oristic diversity and primary
productivity in most cases. Organic matter has
quite high cation exchange capacity and, so,
organic-rich hydric soils i lter water and remove
excess nutrients and other potentially harmful
substances.
The term “soil” would not normally apply to
the l oors or shores of shallow lakes, streams
or seas below the limit of low tide or continu-
ous submergence. Yet, these types of wetlands
are included in the Ramsar dei nition (to a
depth of 6 m). Thus, all types of substrates
must be considered in fresh and marine envi-
ronments, including well-consolidated bedrock,
unconsolidated clastic and bioclastic sediments,
chemical precipitates, and reefs built by organic
activity.
