9.5 Riparian Vegetation as Pollutants Scrubber
9.5.1 Ecology of Vegetation
Plant ecology is a wholesome branch of ecological sciences studying how plants
interact with their abiotic and biotic environment. These interactions vary in terms of
type of species dominating a particular region. The riparian plants acquiring a
different physical habitat have altogether different ecological attributes. In order to
understand how riparian plants maintain the water quality of the river, it is very
important to understand the riparian plant ecology. The likelihood that a particular
riparian vegetation type will occur in a given watershed depends on the ecological
tolerances of the component plant species and their adaptations for specific
hydrogeomorphic conditions, along with water availability, anaerobic soils, surface
characteristics and flood disturbance regimes (Steiger et al. 2005). The functionality
of riparian vegetation in controlling the water pollutant is dependent over the
structural physiological traits of vegetation such as size, form, growth rate, longevity
and litter quality (Dosskey et al. 2010). Not only the type but age of vegetation can
also play an important role in pollutant removal as the efficiency of the plants
declines with age.
The riparian plants vary from region to region so is the ecology; thus, it becomes
essential to study the kind of riparian vegetation harbouring the bank of the rivers
(Fig. 9.3). Internationally there have been numerous studies both in field and in
laboratory to analyse the riparian vegetation for their composition and potency to
remove pollutants. The vegetation types analysed are grass riparian ecotone and
forested riparian ecotone. Parkyn (2004) reported that most of the researchers have
studied the efficiencies of vegetated filter strips of rank paddock grasses. However,
in Indian context, the riparian vegetation is studied mostly in terms of determining
floristic composition of the species, and very few emphasised their role in removing
pollutants. The riparian vegetation reported is diversified across the rivers from plain
to mountains (Fig. 9.3). The species reported from plains are Prosopis sp., Acacia
sp., Azadirachta sp. and Jatropha sp., along the river Yamuna in the floodplain (Jha
et al. 2010), whereas Rhododendron sp., Quercus sp., Woodfordia sp., Oxalis sp.,
Tridax sp., etc. have been reported from Bhilangna River (tributary of river
Bhagirathi) of the Himalayan region.
9.5.2 Mechanism of Pollutant Removal
The plants have their own mechanism and processes for removal of the pollutants,
and both above and below ground biomass structure determine the effects of
vegetation on river water quality (Dosskey et al. 2010). The riparian vegetation is
a community with high productivity resulting in higher nutrient uptake from soil and
groundwater via its own growth. Long back in 1985, it has been established that the
9 Riparian Ecotones: An Important Derivative for Managing River Pollution
209
9.5.1 Ecology of Vegetation
Plant ecology is a wholesome branch of ecological sciences studying how plants
interact with their abiotic and biotic environment. These interactions vary in terms of
type of species dominating a particular region. The riparian plants acquiring a
different physical habitat have altogether different ecological attributes. In order to
understand how riparian plants maintain the water quality of the river, it is very
important to understand the riparian plant ecology. The likelihood that a particular
riparian vegetation type will occur in a given watershed depends on the ecological
tolerances of the component plant species and their adaptations for specific
hydrogeomorphic conditions, along with water availability, anaerobic soils, surface
characteristics and flood disturbance regimes (Steiger et al. 2005). The functionality
of riparian vegetation in controlling the water pollutant is dependent over the
structural physiological traits of vegetation such as size, form, growth rate, longevity
and litter quality (Dosskey et al. 2010). Not only the type but age of vegetation can
also play an important role in pollutant removal as the efficiency of the plants
declines with age.
The riparian plants vary from region to region so is the ecology; thus, it becomes
essential to study the kind of riparian vegetation harbouring the bank of the rivers
(Fig. 9.3). Internationally there have been numerous studies both in field and in
laboratory to analyse the riparian vegetation for their composition and potency to
remove pollutants. The vegetation types analysed are grass riparian ecotone and
forested riparian ecotone. Parkyn (2004) reported that most of the researchers have
studied the efficiencies of vegetated filter strips of rank paddock grasses. However,
in Indian context, the riparian vegetation is studied mostly in terms of determining
floristic composition of the species, and very few emphasised their role in removing
pollutants. The riparian vegetation reported is diversified across the rivers from plain
to mountains (Fig. 9.3). The species reported from plains are Prosopis sp., Acacia
sp., Azadirachta sp. and Jatropha sp., along the river Yamuna in the floodplain (Jha
et al. 2010), whereas Rhododendron sp., Quercus sp., Woodfordia sp., Oxalis sp.,
Tridax sp., etc. have been reported from Bhilangna River (tributary of river
Bhagirathi) of the Himalayan region.
9.5.2 Mechanism of Pollutant Removal
The plants have their own mechanism and processes for removal of the pollutants,
and both above and below ground biomass structure determine the effects of
vegetation on river water quality (Dosskey et al. 2010). The riparian vegetation is
a community with high productivity resulting in higher nutrient uptake from soil and
groundwater via its own growth. Long back in 1985, it has been established that the
9 Riparian Ecotones: An Important Derivative for Managing River Pollution
209