and morphometric variables. Bedrock lithology is also an important feature determining the riparian vegetation composition.
9.6.2 Hydrology of the Riparian Ecotone
Among the several abiotic (e.g. water chemistry, light and wind) and biotic
(e.g. competition, invasive species; see in the succeeding paragraphs) factors that
influence riparian vegetation processes, fluvial hydrodynamics (i.e. flow and flood
regime and related processes) plays a significant role in all plant life stages,
i.e. dispersal, colonisation, recruitment, growth, succession and mortality (Solari
et al. 2016). Successful riparian plants often adopt a combination of adaptive
strategies during different life stages in order to ensure their survival (e.g. high
dispersal rates, adaptations to resist stress and vegetative reproduction; Camporeale
et al. 2013).
Norris, 1993, stated that “effectiveness of riparian buffer ecotone depends upon
the rate of flow of surface water, hydraulic conductivity and holding capacity of the
buffer zone soil”. The water or upland flow which passes through the watershed via
riparian ecotone exhibits variable random forcing over the vegetation among which
the important one is flow variability (Vesipa et al. 2017). The river stage and velocity
affect the riparian environment. The variability in the flow regime of the river affects
the riparian vegetation from its establishment to its death. The river flow of ample
magnitude is needed to remove the vegetation already harbouring the riverbank
(Holanda et al. 2005) and further depositing the fresh sediments for the recruitment
of new seeds of plants.
The rivers also are known to be associated with the phenomenon of hydrochory.
For hydrochory to take place, it is essential that the river shows fluctuations in its
flows (Greet et al. 2011). The rise and fall of the river are essential for collection and
deposition of seeds (Vesipa et al. 2017). Certain hydraulic conditions such as
Froude, Reynolds and Shield number associated with river hydrographs determine
the number of seeds scoured or deposited. Other than the recruitment of seeds, the
flow of the river also plays an important role in determining whether the seed will
germinate and grow into an adult (Fraaije et al. 2015). Both the sudden decline and
sudden rise in river water affect the growth of the seedling.
These river flows are also associated with effects on the adult vegetation in their
life stage (Garssen et al. 2015). The river flow affects the age and spatial distribution
of populations (Mosner et al. 2011). River flow fluctuations affect the stratigraphy of
riverbanks (Merritt et al. 2010). The variability in river flow is also responsible for
transport of nutrients and salts which are required for the sustenance of vegetation
(Asaeda and Rashid 2014). Thus, river flow is the important driver of riparian
vegetation.
9 Riparian Ecotones: An Important Derivative for Managing River Pollution
215
9.6.2 Hydrology of the Riparian Ecotone
Among the several abiotic (e.g. water chemistry, light and wind) and biotic
(e.g. competition, invasive species; see in the succeeding paragraphs) factors that
influence riparian vegetation processes, fluvial hydrodynamics (i.e. flow and flood
regime and related processes) plays a significant role in all plant life stages,
i.e. dispersal, colonisation, recruitment, growth, succession and mortality (Solari
et al. 2016). Successful riparian plants often adopt a combination of adaptive
strategies during different life stages in order to ensure their survival (e.g. high
dispersal rates, adaptations to resist stress and vegetative reproduction; Camporeale
et al. 2013).
Norris, 1993, stated that “effectiveness of riparian buffer ecotone depends upon
the rate of flow of surface water, hydraulic conductivity and holding capacity of the
buffer zone soil”. The water or upland flow which passes through the watershed via
riparian ecotone exhibits variable random forcing over the vegetation among which
the important one is flow variability (Vesipa et al. 2017). The river stage and velocity
affect the riparian environment. The variability in the flow regime of the river affects
the riparian vegetation from its establishment to its death. The river flow of ample
magnitude is needed to remove the vegetation already harbouring the riverbank
(Holanda et al. 2005) and further depositing the fresh sediments for the recruitment
of new seeds of plants.
The rivers also are known to be associated with the phenomenon of hydrochory.
For hydrochory to take place, it is essential that the river shows fluctuations in its
flows (Greet et al. 2011). The rise and fall of the river are essential for collection and
deposition of seeds (Vesipa et al. 2017). Certain hydraulic conditions such as
Froude, Reynolds and Shield number associated with river hydrographs determine
the number of seeds scoured or deposited. Other than the recruitment of seeds, the
flow of the river also plays an important role in determining whether the seed will
germinate and grow into an adult (Fraaije et al. 2015). Both the sudden decline and
sudden rise in river water affect the growth of the seedling.
These river flows are also associated with effects on the adult vegetation in their
life stage (Garssen et al. 2015). The river flow affects the age and spatial distribution
of populations (Mosner et al. 2011). River flow fluctuations affect the stratigraphy of
riverbanks (Merritt et al. 2010). The variability in river flow is also responsible for
transport of nutrients and salts which are required for the sustenance of vegetation
(Asaeda and Rashid 2014). Thus, river flow is the important driver of riparian
vegetation.
9 Riparian Ecotones: An Important Derivative for Managing River Pollution
215