Flora
Diversity within várzea varies greatly, both with flora and fauna. The amazing thing about these plants is that they must be adapted to survive months of flooding. This section will discuss flora, broken down by each várzea, organized by distance from the mouth of the Amazon.
Marajó:
Marajó,
lying at the mouth of the Amazon River, has numerous islands. The
flooding captures nutrient rich soils, which will eventually make their
way downriver. The vegetation at Marajó
is short (the forest has a lower canopy than normal), and plant
diversity is lower than other várzea. Forest species are
dominated by palms. In addition, Marajó
contains small areas of seasonally inundated floodplain forest, and
permanently inundated swamp forest. There is also an estuarine
(tidal) várzea
forest, on the western side of Marajó island, the eastern side
of which is covered by a flooded savanna and a humid terra firme forest
(this forest is distinct from the estuarine forest on the west).Many areas with in the várzea forest are dominated by stands of the buriti (Mauritia flexuosa, see picture below) and açaí palms (Euterpe oleraceae, see picture below), which are economically important. Other palm species are represented (at least 9 abundant ones, plus many more). Ficus species are also present. The fruit from many of these trees is an important food for grazing animals on the river bank. These species include gray brocket deer (Mazama gouazoubira), red brocket deer (Mazama americana), and capybaras (Hydrochaeris hydrochaeris).
Gurupa:
Gurupa contains areas of flooded savanna, as well as forest and river
areas. In the flooded savanna, large grasses and sedges occur.
In the transition between forest and river, shrubs and small
vines occur. The forest
includes many large trees. The trees are highly diverse.
Some produce fleshy fruit that is important for fruit eating
species of fish (likely an adaptation to the flooding), primates, and
bats. Some of these trees are yellow mombim (Spondias mombim); palms, including buriti and açaí; socoró (Mouriri ulei); and tarumã (Vitex cymosa).Monte Alegre:
This várzea
has four vegetation types. These are created by the influence of
the flood cycle. The first three are on the meandering of the
floodplains, and result from the instability of the river routes.
These are successional vegetation, forest mosaics, and aquatic
vegetation in poorly draining areas. The fourth type is found in
flooded river basins, and is permanent swamp vegetation.Monte Alegre is known by its seasonally flooded evergreen moist tropical forest, even though it has many different vegetation types. These forests often have less tree species than the terre firme forest. Some species are restricted to the wetland areas (ex: Euterpe oleraceae, Virola surinamensis, see below), and many are found in terra firme. The tree canopy in the várzea is usually shorter, reaching 25 m. This forest usually has a dense understory of large-leaved herbaceous plants, including Zingiberaceae (see example below, but please note that this particular species may not be located in Monte Alegre, it is just a sample of the family), Maranthaceae, and Heliconiaceae families.
Monte Alegre also has patches of grassland, which are known locally as canarana.
Purus:
This várzea
is very similar to Monte Alegre, probably due to their proximity.
One difference is that it does not seem to contain the grassland,
canarana. Purus has several economically important tree species
for timber. Palms are somewhat rare. In low areas, the várzea has bamboo (Bambusca sp.). This is abundant, along with pioneer trees, including many species of ficus. Ceiba pentandra is the largest tree, and will often have immense buttress roots (see below).
Iquitos:
Many aspects of the Iquitos várzea are similar to Monte Alegre and Purus. At Iquitos (and probably similar in other várzea),
species composition can change dramatically, with an elevation change
of only a few meters. different terrestrial and aquatic
components at Iquitos dominate depending on season. During the
low water season, trees and aquatic herbaceous vegetation simply rest
on the ground. Iquitos is characterized by evergreen tropical forest. This forest has a complex, layered vertical structure. River flow keeps the forest in different successional stages. Young vegetation is mostly grasses. Next is woody shrubs, then early successional trees. Late successional parts of the forest exist on ancient alluvial terraces.
Buriti and other economically important trees exist in Iquitos. Shrubs, known as camucamu fruit (Myrciaria dubia) grow on the waters edge, and seem to do well with the long flood season. Epiphytes are also common.
buriti palm Virola surinamensis Virola surinamensis (fruit)
açaí palm (Euterpe oleraceae) Tapeinochilus ananassae Ceiba pentandra
Zingiberaceae family
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