171
time, even could be in the absence of any direct
evidence of change.
8.4.3 The Diffi culties of the
Phytosociological Approach
Today, a number of plant ecologists might have
been realising that the diffi culties with any
phytosociological approach lie in attempting to
defi ne communities along a gradient on which
individual species are distributed to a greater
or lesser extent independently of each other
(Whittaker 1967 ).
8.5
AM of Certain Lakes of the
World
The aquatic macrophytes (AM) are interesting
forms of plant life. As compared to the terrestrial
plants, the aquatic plants remain comparatively
less affected by the climatic and seasonal
changes. Consequently, it is more feasible to
study the plants for the greater part of the year.
Further, they also exhibit striking adaptations to
fi t in the aquatic regime.
8.5.1 AM of the Lakes of Indonesia
Ruttner, in the course of his work on the German
Limnological Expedition of 1928–1929, made a
number of observations on the macrophytic vegetation of lakes in Java, Sumatra and Bali. The
fl ora of the deeper water usually included
Hydrilla verticillata , which had occurred in 9 out
of 12 lakes studied. This was generally a dominant fl ora and was one of the most widespread
aquatic angiosperms encountered. This plant
could reach a depth of 8 m in Lake Singkarak in
Central Sumatra. It, however, reached a lesser
depth in other more transparent lakes of the
region. H. verticillata was associated with Najas
falciculata in four lakes, with P. malayanus in
three lakes and with P. pectinatus and with
Ceratophyllum demersum in two lakes.
The most extensive submerged AM is said to
occur in Lake Toba, which is the largest lake in
this Indonesian Islands. In Lake Toba, angiosperms had been recorded monthly up to a depth
of 5 m. At this depth, AM like H. verticillata and
P. malayanus were also recorded in Lake Toba.
The marginal vegetation is very diverse. On
fl at sandy shores, it was found to consist of sparse
Panicum repens with Nymphoides cristata .
Lake Singkarak is another quite large lake in
Central Sumatra. In this lake, H. verticillata had
been found to occur up to a depth of 8 m. P. malayanus grew in less deep water. In quite shallow areas,
from 0.5 to 1.0 m depth, there was a reduced form
of this species. This was perhaps clearly infl uenced
by mechanical disturbance. Marginally, in quiet
bays, N. indicum were found to form beautiful
patches with large fl oating leaves and white fl owers.
Locally, there is a marginal swamp vegetation of
Cyperus sp., Polygonum barbatum growing in up to
40 cm and Eleocharis dulcis in up to 70 cm of
water; Ipomoea aquatica was found to sprawl over
the water surface, and at the margin were found
large grasses like Saccharum spontaneum , etc.
Danau Diatas is a small lake in the same broad
region. It was found to have quite dilute water
though an alkaline pH. This lake was found to have
P. polygonifolius as the submerged AM. Shoots of
Hydrilla were found fl oating at the surface.
Lake Ranau is another Sumatran lake. This
lake had an association of P. pectinatus and
H. verticillata which was found to be well developed at a depth of 1–7 m of water. Isolated specimens of the Hibiscus tiliaceus, etc ., were found to
grow in places where waves may break over the
bases of the trunks and branches dip into the water.
The Lake Ranu Lamongan in East Java had
H. verticillata and C. demersum to a depth of 5 m
with Eichhornia crassipes, Spirodela polyrhiza
and Azolla pinnata, with Colocasia esculenta
here and there. Ipomoea aquatica was found to
grow out over the water twining among the most
superfi cial plants of Hydrilla . The marginal vegetation had also included Typha domingensis , the
grass Eriochloa subglabra, Polygonum barbatum
and Jussiaea repens . The trees like Barringtonia
racemosa , etc. grew along the lake margins.
8.5 AM of Certain Lakes of the World
time, even could be in the absence of any direct
evidence of change.
8.4.3 The Diffi culties of the
Phytosociological Approach
Today, a number of plant ecologists might have
been realising that the diffi culties with any
phytosociological approach lie in attempting to
defi ne communities along a gradient on which
individual species are distributed to a greater
or lesser extent independently of each other
(Whittaker 1967 ).
8.5
AM of Certain Lakes of the
World
The aquatic macrophytes (AM) are interesting
forms of plant life. As compared to the terrestrial
plants, the aquatic plants remain comparatively
less affected by the climatic and seasonal
changes. Consequently, it is more feasible to
study the plants for the greater part of the year.
Further, they also exhibit striking adaptations to
fi t in the aquatic regime.
8.5.1 AM of the Lakes of Indonesia
Ruttner, in the course of his work on the German
Limnological Expedition of 1928–1929, made a
number of observations on the macrophytic vegetation of lakes in Java, Sumatra and Bali. The
fl ora of the deeper water usually included
Hydrilla verticillata , which had occurred in 9 out
of 12 lakes studied. This was generally a dominant fl ora and was one of the most widespread
aquatic angiosperms encountered. This plant
could reach a depth of 8 m in Lake Singkarak in
Central Sumatra. It, however, reached a lesser
depth in other more transparent lakes of the
region. H. verticillata was associated with Najas
falciculata in four lakes, with P. malayanus in
three lakes and with P. pectinatus and with
Ceratophyllum demersum in two lakes.
The most extensive submerged AM is said to
occur in Lake Toba, which is the largest lake in
this Indonesian Islands. In Lake Toba, angiosperms had been recorded monthly up to a depth
of 5 m. At this depth, AM like H. verticillata and
P. malayanus were also recorded in Lake Toba.
The marginal vegetation is very diverse. On
fl at sandy shores, it was found to consist of sparse
Panicum repens with Nymphoides cristata .
Lake Singkarak is another quite large lake in
Central Sumatra. In this lake, H. verticillata had
been found to occur up to a depth of 8 m. P. malayanus grew in less deep water. In quite shallow areas,
from 0.5 to 1.0 m depth, there was a reduced form
of this species. This was perhaps clearly infl uenced
by mechanical disturbance. Marginally, in quiet
bays, N. indicum were found to form beautiful
patches with large fl oating leaves and white fl owers.
Locally, there is a marginal swamp vegetation of
Cyperus sp., Polygonum barbatum growing in up to
40 cm and Eleocharis dulcis in up to 70 cm of
water; Ipomoea aquatica was found to sprawl over
the water surface, and at the margin were found
large grasses like Saccharum spontaneum , etc.
Danau Diatas is a small lake in the same broad
region. It was found to have quite dilute water
though an alkaline pH. This lake was found to have
P. polygonifolius as the submerged AM. Shoots of
Hydrilla were found fl oating at the surface.
Lake Ranau is another Sumatran lake. This
lake had an association of P. pectinatus and
H. verticillata which was found to be well developed at a depth of 1–7 m of water. Isolated specimens of the Hibiscus tiliaceus, etc ., were found to
grow in places where waves may break over the
bases of the trunks and branches dip into the water.
The Lake Ranu Lamongan in East Java had
H. verticillata and C. demersum to a depth of 5 m
with Eichhornia crassipes, Spirodela polyrhiza
and Azolla pinnata, with Colocasia esculenta
here and there. Ipomoea aquatica was found to
grow out over the water twining among the most
superfi cial plants of Hydrilla . The marginal vegetation had also included Typha domingensis , the
grass Eriochloa subglabra, Polygonum barbatum
and Jussiaea repens . The trees like Barringtonia
racemosa , etc. grew along the lake margins.
8.5 AM of Certain Lakes of the World