299
The turbidity ranged from 20.56 to 185.54
TU, while the overall thermal trend of the wetland depicted a state of isothermy with a bimodal
peak occurring during summer and monsoon.
The water temperature varied from 18.7 to
32.3 °C, and it followed the air temperature fairly
closely. The water of the Beel was circum-neutral
with pH varying from 6.0 to 7.9, DO ranging
from 2.6 to 5.9 mg/l, FCO 2 fl uctuating from 0.9
to 14.5 mg/l and TA lying between 25.0 and
76.0 mg/l. The solubility of DO ranged from 9.4
to 11.9 mg/l, while its % saturation varied from
32.3 to 74.4 %. DO portrayed an inverse relation
with temperature and FCO 2 , but a direct with pH
and TA. As an index of dissolved salts, the conductivity of Sone water was low. The lake soil
was quite unproductive with pH ranging from 4.9
to 5.0, OC 0.25–1.74 %, available phosphorus
ranging from 0.15 to 1.93 mg/100 g of soil and
available potassium 1.6 to 24.8 mg/100 g.
Aquatic Macrophytes (AM)
AM was found to exhibit a heterogeneous assemblage of 23 species in Sone Beel. The species
composition of AM has been mentioned in Chap.
15 . It may be noted here that association of different species of AM, forming phyto-social
units, is generally encountered in the wetlands.
In Sone Beel, amongst the fl oating varieties, S.
cucullata and A. pinnata and N. cristatum and N.
indicum were found to form distinct phyto-social
units. Amongst the emergent varieties, E. acutangula and S. trifolia and S. eriophorum and
E. stagnina were found to be associated together.
Amongst the submerged types, H. verticillata,
V. spiralis and N. alternifolia were found to
make an association. Interestingly, T. bispinosa,
the fl oating form, also exhibited association with
this group. Further, E. crassipes and E. ferox
were found to remain solitary and thus formed
monospecifi c unit.
AM biomass was found to vary from 0.58 to
21.90 kg/m
2 (average 2.48 ± 0.82) having the
maximum in December and the minimum in
May. In addition to water level (WL) and amplitude of fl ooding (Welcomme 1979 ), the growth
and distribution of the AM was found to be infl uenced by water quality of the wetland.
E. crassipes was the sole perennial species in
the wetland, followed by H. verticillata and T.
bispinosa, occurring during most of the months of
the year. During dry season, the emergent varieties (like E. stagnina, E. acutangula, S. eriophorum, O. sativa, S. trifolia and P. fl accidum ) and the
submerged types (like H. verticillata, V. spiralis )
generally succeed, fl ourish and show abundance at
less WL when the wetland exhibits a decreasing
trend in its depth. It indicates an indirect relation of
AM biomass with WL ( r = − 0.130 ± 0.442.
P > 0.05) during this period. Higher ranges of conductivity at this time were found to sustain
(Pearsall 1938 ) a rich biomass of T. bispinosa.
The wetland water, during dry season, in general, portrays high DO produced by photosynthesis at rich insolation, in which FCO 2 is consumed
and shows a fall. Concomitantly, a direct relationship of AM biomass with DO
( r = 0.500 ± 0.340, P < 0.05) and an inverse with
FCO 2 ( r = −0.780 ± 0.178, P < 0.05) was recorded
in the study. The pH and TA, which were found
to depict rise, portrayed their direct relationship
( r = 0.850 ± 0.126, P < 0.05; r = 0.022 ± 0.454,
P < 0.05) with AM biomass. H. verticillata and V.
spiralis, as indicated earlier, were found to be
closely ( P < 0.05) associated during this period
( χ
2 , 34.67). Also, a close ( P < 0.05) association
between fl oating T. bispinosa and submerged V.
spiralis ( χ
2 , 24.15) and between submerged H.
verticillata and emergent S. eriophorum ( χ
2 ,
31.89) was discernible during the period.
With the onset of monsoon, the fl oating varieties, namely, N. nouchali, N. cristatum and N.
indicum , generally occur in their fl owering stage.
Most of the emergent varieties encountered during winter, spring and summer get submerged
and decayed during monsoon. However, the littoral and sublittoral zones of the Beel, during
monsoon, are generally found to be moderately
infested with emergent varieties like C. dactylon
and V. zizanioides. H. verticillata, amongst the
submerged varieties, do, sometimes, occur. Onset
of monsoon, as stated earlier, causes decay of
20.2 Wetlands of Northeast India (The Water Wealth of Northeast India)
The turbidity ranged from 20.56 to 185.54
TU, while the overall thermal trend of the wetland depicted a state of isothermy with a bimodal
peak occurring during summer and monsoon.
The water temperature varied from 18.7 to
32.3 °C, and it followed the air temperature fairly
closely. The water of the Beel was circum-neutral
with pH varying from 6.0 to 7.9, DO ranging
from 2.6 to 5.9 mg/l, FCO 2 fl uctuating from 0.9
to 14.5 mg/l and TA lying between 25.0 and
76.0 mg/l. The solubility of DO ranged from 9.4
to 11.9 mg/l, while its % saturation varied from
32.3 to 74.4 %. DO portrayed an inverse relation
with temperature and FCO 2 , but a direct with pH
and TA. As an index of dissolved salts, the conductivity of Sone water was low. The lake soil
was quite unproductive with pH ranging from 4.9
to 5.0, OC 0.25–1.74 %, available phosphorus
ranging from 0.15 to 1.93 mg/100 g of soil and
available potassium 1.6 to 24.8 mg/100 g.
Aquatic Macrophytes (AM)
AM was found to exhibit a heterogeneous assemblage of 23 species in Sone Beel. The species
composition of AM has been mentioned in Chap.
15 . It may be noted here that association of different species of AM, forming phyto-social
units, is generally encountered in the wetlands.
In Sone Beel, amongst the fl oating varieties, S.
cucullata and A. pinnata and N. cristatum and N.
indicum were found to form distinct phyto-social
units. Amongst the emergent varieties, E. acutangula and S. trifolia and S. eriophorum and
E. stagnina were found to be associated together.
Amongst the submerged types, H. verticillata,
V. spiralis and N. alternifolia were found to
make an association. Interestingly, T. bispinosa,
the fl oating form, also exhibited association with
this group. Further, E. crassipes and E. ferox
were found to remain solitary and thus formed
monospecifi c unit.
AM biomass was found to vary from 0.58 to
21.90 kg/m
2 (average 2.48 ± 0.82) having the
maximum in December and the minimum in
May. In addition to water level (WL) and amplitude of fl ooding (Welcomme 1979 ), the growth
and distribution of the AM was found to be infl uenced by water quality of the wetland.
E. crassipes was the sole perennial species in
the wetland, followed by H. verticillata and T.
bispinosa, occurring during most of the months of
the year. During dry season, the emergent varieties (like E. stagnina, E. acutangula, S. eriophorum, O. sativa, S. trifolia and P. fl accidum ) and the
submerged types (like H. verticillata, V. spiralis )
generally succeed, fl ourish and show abundance at
less WL when the wetland exhibits a decreasing
trend in its depth. It indicates an indirect relation of
AM biomass with WL ( r = − 0.130 ± 0.442.
P > 0.05) during this period. Higher ranges of conductivity at this time were found to sustain
(Pearsall 1938 ) a rich biomass of T. bispinosa.
The wetland water, during dry season, in general, portrays high DO produced by photosynthesis at rich insolation, in which FCO 2 is consumed
and shows a fall. Concomitantly, a direct relationship of AM biomass with DO
( r = 0.500 ± 0.340, P < 0.05) and an inverse with
FCO 2 ( r = −0.780 ± 0.178, P < 0.05) was recorded
in the study. The pH and TA, which were found
to depict rise, portrayed their direct relationship
( r = 0.850 ± 0.126, P < 0.05; r = 0.022 ± 0.454,
P < 0.05) with AM biomass. H. verticillata and V.
spiralis, as indicated earlier, were found to be
closely ( P < 0.05) associated during this period
( χ
2 , 34.67). Also, a close ( P < 0.05) association
between fl oating T. bispinosa and submerged V.
spiralis ( χ
2 , 24.15) and between submerged H.
verticillata and emergent S. eriophorum ( χ
2 ,
31.89) was discernible during the period.
With the onset of monsoon, the fl oating varieties, namely, N. nouchali, N. cristatum and N.
indicum , generally occur in their fl owering stage.
Most of the emergent varieties encountered during winter, spring and summer get submerged
and decayed during monsoon. However, the littoral and sublittoral zones of the Beel, during
monsoon, are generally found to be moderately
infested with emergent varieties like C. dactylon
and V. zizanioides. H. verticillata, amongst the
submerged varieties, do, sometimes, occur. Onset
of monsoon, as stated earlier, causes decay of
20.2 Wetlands of Northeast India (The Water Wealth of Northeast India)