Article
Interactions between riparian
vegetation and fluvial processes
within tropical Southeast Asia:
Synthesis and future directions
for research
Progress in Physical Geography
2014, Vol. 38(6) 716–733
ª The Author(s) 2014
Reprints and permission:
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DOI: 10.1177/0309133314548745
ppg.sagepub.com
Helen L. Moggridge
University of Sheffield, UK
David L. Higgitt
University of Nottingham Ningbo China, China
Abstract
Research on the interaction between vegetation and hydrological and geomorphological processes has made
a significant advancement in river and floodplain research. While this work is strongly dominated, both
conceptually and empirically, from studies in northern temperate systems, it has been instrumental in shaping
understanding at a global scale. There are, however, regions of the world such as tropical Southeast Asia
which have received relatively little research attention, but could offer an important contribution to
knowledge in this field. In a first step to address this issue, this paper synthesizes current research on
vegetation and geomorphology and hydrology within tropical Southeast Asia, to consider the applicability of
current (temperate-based) models and the potential contribution that processes within these systems could
make to global understanding. While research within the region is sparse, observations suggest a reciprocal
relationship between vegetation and fluvial processes. While there are some synergies with temperate systems,
processes within this region also present interesting differences which could, with further investigation, advance
current understanding of these processes globally and expand and enhance current concepts. The paper
concludes with the identification of the pertinent research questions for the field within the region.
Keywords
fluvial geomorphology, hydrology, large wood, Southeast Asia, tropical, vegetation
I Background and introduction
The reciprocal role between vegetation and
physical processes in rivers and their wetlands
has received considerable research interest in
recent decades, both conceptually (e.g. Corenblit et al., 2007; Fisher et al., 2007) and empirically (e.g. Bertoldi et al., 2011). Studies have
shown that hydrological and geomorphological
processes can influence vegetation composition
(Bendix and Hupp, 2000), by creating a mosaic
of heterogeneous habitats (which vary in disturbance frequency and intensity and nutrient and
moisture availability) and through facilitating
Corresponding author:
Helen L. Moggridge, Department of Geography, Winter
Street, University of Sheffield, Sheffield S10 2TN, UK.
Email: [email protected]
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Moggridge and Higgitt
717
the dispersal, establishment and growth of vegetation (Greet et al., 2011; Steiger et al., 2005).
The active physical role that established vegetation can have in subsequently modifying these
physical processes has also been well studied;
vegetation modifies water flows and sediment
dynamics (e.g. Tabacchi et al., 2000), causing
rivers to develop new landforms (e.g. Bertoldi
et al., 2011), alter meander migration rates
(e.g. Perucca et al., 2007), influence braiding
patterns (Coulthard, 2005; Tal et al., 2004) and
create anastomosing planforms (Tooth and
Nanson, 1999, 2000). This reciprocal relationship is comprehensively reviewed in temperate
river systems by Corenblit et al. (2009a) and
Gurnell et al. (2012).
The foundation for much of this research was
the notable and widely cited Flood Pulse Concept (Junk et al., 1989), which introduced the
idea that lateral connectivity within fluvial systems, through periodic inundation of floodplains, was ecologically significant. This was
based on field data for fish communities in large
rivers in the Neotropics and North America and
has underpinned subsequent research on physical and ecological linkages within river systems
worldwide (Junk and Wantzen, 2004). The concept has since been advanced in tropical rivers;
fish ecology has been explicitly linked with particular aspects of the flood pulse, such as the
timing, continuity (i.e. absence of any disruption from floods), smoothness (i.e. steadiness
of the rise and fall), rapidity of change amplitude and duration of the flood pulse (see Welcomme and Halls, 2004, and references
therein). Research has also broadened to consider riparian vegetation; several studies on the
Parana and Amazon rivers have demonstrated
that the flood pulse interacts with geomorphological processes to create a heterogenous mosaic
of different landforms and wetland types, which
all support distinct vegetation communities and
contribute to the diversity of these systems
(Hamilton et al., 2007; Kalliola et al., 1991;
King, 2003; Lamotte, 1990; Marchetti et al.,
2013; Mertes et al., 1995; Stevaux et al., 2013).
Research from tropical Africa shows similar relationships (Hughes, 1990; Medley, 1992, and
references therein), although few studies exist.
The tropical origin of the Flood Pulse Concept is, however, rather anomalous in river
research. While there have been notable
advances in research within the tropics (and
across all ecoregions), northern temperate systems have received a particular focus. Most of
the key models that precede (e.g. River Continuum Concept, Vannote et al., 1980) or follow
on from the Flood Pulse Concept (e.g. Shifting
Habitat Mosaic, Stanford, 1998; Flow Pulse
Concept, Tockner et al., 2000; River Ecosystem
Synthesis, Thorp et al., 2006) are heavily based
on research within the temperate zone and these
models are being used to guide research questions and management approaches in rivers
worldwide (Boulton et al., 2008).
The strong geographical foci of this research
constrains understanding to a limited number of
climates, flow regimes and vegetation types,
which ultimately limits the depth of understanding of these processes and leaves many systems
under-researched. Key examples are the Southeast Asian monsoonal river and floodplain systems. These systems are characterized by
exceptionally high biodiversity (e.g. Keogh
et al., 1999) and deliver important ecosystem
services (Jusoff and Majid, 1990), but are
acknowledged as being some of the least studied
biotopes in the region (Anderson, 1983; Dudgeon, 2000a). Further, the research that is conducted in this region rarely captures a global
audience; ‘[studies] dealing with tropical rivers
seem generally to be perceived as interesting
regional studies first and contributions to limnology second; studies of north-temperate
waters are viewed in the opposite way’ (Dudgeon, 2000a: 258). This lack of research is also
confounded by the extensive degradation and
decline of these systems (Dudgeon, 1992,
2000b). Thus, there is an urgent and important
need for future research to consider these
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Progress in Physical Geography 38(6)
120°E
100°E
140°E
Mek
utr
ong
Brahmap
a
C h i n a
Irr
awa
ddy
Bangladesh
Burma
20°N
20°N
Thailand
Cha o
Phr
ay
a
Loas
Vietnam
Philippines
Cambodia
Pacific
Ocean
M a l a y s i a
Equator
Borneo
Sumatra
Papau
New Guinea
I n d o n e s i a
Fl
y
Java
Indian
Ocean
0
1000
km
20°S
100°E
Australia
120°E
140°E
20°S
Figure 1. Map of the study area, Southeast Asia and the surrounding tropical monsoon regions. The largest
rivers of the region are shown.
systems, to investigate the applicability of existing models, to contribute to global understanding of vegetation and fluvial processes and to
inform effective management.
This paper will synthesize existing studies
within tropical Asia to develop a basic conceptual understanding of the physical role of vegetation in rivers and their wetlands. The focus area
of the study (shown in Figure 1) are rivers within
monsoonal Southeast Asia, with consideration,
where appropriate, of tropical rivers extending
to India, Papua New Guinea and tropical northern Australia. Relevant studies from the wider
tropical latitude of 23 N and 23 S are also used
to support discussion. The paper will present an
initial comparative evaluation of the synergies
and contrasts between models derived from the
temperate zone and observation from tropical
rivers and identify the principal research directions for future study. While ecological comparisons have been made between temperate and
tropical streams previously (see Boulton et al.,
2008, for an overview) and the geomorphology
of tropical rivers has been reviewed (see Latrubesse et al., 2005, for a global review of tropical
systems and Gupta, 2005, for a regional overview), there is little available information on rivers within this region. Further, vegetation within
rivers and its interaction with fluvial processes
have not been previously considered in Southeast
Asia, with existing work on tropical rivers being
almost entirely confined to the Neotropics.
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Moggridge and Higgitt
719
II Southeast Asian rivers
and floodplains
A principal distinction between temperate and
tropical rivers is the flow regime, which is critical to determining vegetation distribution, survival and growth (Greet et al., 2011). Southeast
Asia exhibits a wet tropical climate, with annual
rainfall typically exceeding 2500 mm. This
drives the flow regime, as all the rivers within
the region are rain fed (Gupta, 2005). Seasonality within the region is driven by two opposite
patterns of monsoon winds and so can vary from
a long, wet season (9–10 months duration) and a
shorter dry season, or two monsoon seasons
(October–March and April–August) (Page
et al., 2006). Close to the equator, seasonality
is less pronounced, but still evident from the
variation in the Intertropical Convergence
Zone. This heterogeneity in seasonality is
reflected in the flow regimes of the river catchments. For example, small equatorial catchments often exhibit little seasonality, with a
flashy variation in discharge, mostly attributable to individual high-magnitude, shortduration storm events (Spencer et al., 1990).
In contrast, many of the larger systems are profoundly influenced by the monsoon, which creates a characteristic pattern of well-defined wet
and dry seasons, usually with the flood peak in
August–September (Dettinger and Diaz, 2000)
although with variation in timing across the
region (Dudgeon, 1992). The intensity of the
monsoon is linked with the El Niño-Southern
Oscillation phenomenon, which drives more
interannual variability in flood magnitude in
this region than is typically associated with tropical rivers (Boulton et al., 2008; Puckridge
et al., 1998). This is also confounded by the
influence of typhoons and tropical cyclones
(Boulton et al., 2008), whose seasonal arrival
coincides with the high flow period and can
cause large-scale flooding.
A defining characteristic of catchments
within this region is the large variation in size;
five of the world’s longest rivers are in tropical
Asia (Mekong, Indus, Brahmaputra, Ganges
and Irrawaddy). The largest river within the
region is the Mekong River, which drains
795,000km3 and has a mean discharge of
15,000 m3s-1 at the mouth (Gupta et al., 2002),
classifying it as a ‘mega-river’ (Latrubesse,
2008). The monsoon rainfall drives the flow
regime of these major river systems, but the
characteristics and behaviour of these rivers are
also fundamentally influenced by tectonics and
Quaternary sea-level changes (Gupta, 2005).
The region is characterized by rapid weathering, driven by heavy rainfall, a steep topography, erodible rocks and high levels of tectonic
activity. This generates high sediment loads,
particularly in the rivers draining large mountainous areas, such as the Brahmaputra, Mekong
and Irrawaddy, and rivers draining the highelevation oceanic islands, including the Fly and
Sepik in Papua New Guinea and small rivers
draining Java and Borneo (Latrubesse et al.,
2005). Sediment transport is tightly coupled to
the rainfall regime and thus strongly pulsed with
the heavy rainfall events (often tropical
cyclones) that characterize the region. Sediment
erosion, transport and deposition (and subsequently all channel-defining processes) exhibit
strong seasonality associated with the wet season (Gupta, 2011); it has been suggested that
over 50% of the sediment eroded within a tropical catchment can be transported in just a few
days in the year (Douglas, 1993).
An initial classification of river types in tropical
South East Asia is proposed in Table 1, based on a
very limited collection of morphological
descriptions of rivers within the region. The
classification distinguishes between confined,
bedrock-controlled rivers and alluvial rivers
with extensive floodplains. Confined systems
include small, steep rivers draining mountainous and volcanic areas, and confined sections
of larger rivers (e.g. Figure 2), which are common within the region. Three major types of
alluvial rivers are identified: meandering,
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Floodplain morphology
Characteristic wetlands and
riparian vegetation assemblages
B: Lowland, alluvial rivers with extensive floodplains
Seasonally inundated wetlands on scroll
B1: Single channel, meandering Floodplain morphology comprising
scroll complexes, abandoned
bars and alluvial plains.
channels, oxbow lakes, alluvial plains Lower elevations characterized by
of minor tributaries and
permanently inundated wetlands,
such as backswamps and blocked
backswamps.
valley swamps, and open-water
habitats, such as oxbow lakes.
Point and channel bars and islands occur Pioneer vegetation may colonize bar
B2: Braided planform, often
within and adjacent to main channel.
tops.
due to a high sediment
supply from draining
Natural levees may occur along
Seasonally inundated wetlands on levee
mountainous reaches
channel banks.
tops.
Permanently inundated wetlands, such
as swamps and shallow lakes, occur
between levees and floodplain.
Periodically inundated vegetation on
B3: Anabranching planforms,
Large bars and islands within the
island tops.
characteristic of the
channel, often with well-developed
Seasonally inundated wetlands on levee
lower reaches of the
vegetation. Floodplains charactervery large river systems
ized by scroll bars, crevasse splays
tops, scroll bars.
and levees (based on studies from
Permanently inundated wetlands at
lower elevations, such as
large Neotropical, anabranching
backswamps and open-water
systems).
habitats, such as shallow lakes.
A: Confined rivers with little or no floodplain
A1: Steep upland, headwater
Rivers are confined by steep banks, with No riparian wetlands. Riparian
streams
no floodplain, especially in upstream
vegetation confined to a narrow
reaches. Lateral bars may form
margin along the main channel.
further downstream.
Possible vegetation colonization of
A2: Narrow, incised rivers
No floodplain, rivers confined and often
in-channel bars and islands.
draining volcanic areas
deeply incised. Prone to significant
modification from episodic
sedimentation from volcanic activity.
A3: Bedrock channels in
Little or no floodplain development,
confined sections of
with channels flowing through
large rivers
gorges. In wider sections, rock cored
in-channel islands may be present
(e.g. Mekong) and bar deposits may
overlay bedrock (e.g. Irrawaddy).
Category description
Lower reaches of Irrawaddy, Ganges
and Mekong at Laos-Cambodia
border (‘4000 Islands’).
Gupta and Liew (2007); Jain et al.
(2012); Marchetti et al.
(2013); Stevaux et al. (2013)
Sections of the Brahmaputra in Assam, Dietrich et al. (1999); Sarma
northwest India.
(2005)
Wider, mountainous reaches in upper
sections of the Fly River, Papua New
Guinea.
Lower reaches of Fly River, Papua New Deitrich et al., (1999); Gupta and
Liew (2007); Gupta et al.
Guinea. Mid- to lower reaches of
(2002); Pickup (1984); Pickup
Chao Phraya, Thailand. Reaches of
and Marshall (2009)
upper Mekong (downstream of
Vientiane, Lao PDR).
Gupta (2005); Gupta and Liew
(2007); Gupta et al. (2002);
Stamp (1940)
Gupta (2005)
Rivers draining volcanic areas of
Sumatra and Java.
Sections of Irrawaddy and upper
Mekong (downstream of
Savannakhet, Lao PDR).
Upper reaches of Chao Phraya,
Thailand.
Gupta (2005)
References
Headwaters of the Pahang, Malaysia.
Examples
Table 1. Classification of the major river types within Southeast Asia, with their characteristic wetlands and vegetation assemblages, with key examples.
Moggridge and Higgitt
721
Figure 2. Rock-cored in-channel island of the
Mekong River, upstream of Chiang Sean, Thailand
(A3). Fine sediment deposited on and between the
rock outcrops creates suitable habitat for colonization of vegetation.
braided and anabranching. The classification is
not intended to be exhaustive, but merely serves
as a framework for discussion. Of particular
note is that the morphology of these rivers can
vary within systems as much as between
them—a characteristic of tropical rivers worldwide (Latrubesse et al., 2005)—with many
larger rivers alternating between bedrockconstrained channels and alluvial channels
(Gupta, 2005) and thus appearing as several
river types in Table 1. For example, the 4880
km course of the Mekong changes from constrained narrow rocky valleys to wide alluvial
basins with meandering planforms (Gupta,
2011), with a complex 4000-island archipelago
at the Lao PDR/Cambodia border which creates
an anabranching planform (Latrubesse et al.,
2005). The smaller Fly River in Papua New
Guinea (catchment area 75,000 km3) exhibits
three distinct morphological zones along its
course (Pickup, 1984): a gorge section in the
mountainous upper reaches, which can be up
to 1000 m deep and has an active hillslope sediment supply, causing poorly developed braiding in the wider sections; a valley section,
characterized by a braided channel, interspersed with vegetated islands; and a meandering section in the lowland alluvial plains,
characterized by a single channel with a floodplain morphology derived from past channel
positions (Dietrich et al., 1999). In certain sections, rivers may traverse river types too; for
example, some meandering sections of the
Mekong exhibit bar-braided planforms at low
flows (Gupta and Liew, 2007) and the Brahmaputra has braided, anabranching reaches
(Sarma, 2005).
Within the active zone of all of these rivers,
flow and sediment dynamics interact to create
a diverse mosaic of vegetation communities,
particularly in the low-gradient rivers with
well-developed floodplains. There is little information on the riparian vegetation of the volcanic and steep, upland rivers (types A1 and
A2), although a description of upland streams
in Kalimantan (Indonesian Borneo) suggests a
diverse riparian fringe vegetation composed of
aroids and leguminous trees (MacKinnon
et al., 1996). No published information was
available on vegetation within the confined sections of larger rivers (A3), although observation
of a rock-confined section of the Mekong
showed vegetation establishment on in-channel
islands (see Figure 2).The floodplains of the
lowland, alluvial rivers (types B1–B3) are
naturally dominated by rainforest vegetation,
which is strongly associated with the flow
regime of the catchment. This is evident in
both the smallest freshwater swamps, found
in areas such as Nee Soon catchment in Singapore (Ng and Lim, 1992) to extensive floodplains, like the 15,000 km2 floodplain of
Tonle Sap (Cambodia) that is inundated during
the flood pulse of the Mekong river (MRC,
2005, cited in Arias et al., 2012). River processes drive heterogeneity within the floodplains. For example, the mosaic of rainforest
floodplain communities of the Fly River are
associated with specific geomorphic features
on the floodplain, such as scroll complexes,
backswamps, alluvial plains of minor tributaries, blocked valley swamp and lakes (Blake
and Oliver, 1971, cited in Dietrich et al., 1999).
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Progress in Physical Geography 38(6)
Figure 3. Extensive mid-channel island on the anabranching lower Irrawaddy, downstream of Pyay,
Burma (B3). Periodically inundated woody vegetation grows at the highest elevations (left) and the
scroll bar comprises seasonally inundated vegetation
and a small backswamp (centre).
While forested floodplains dominate within
the region, natural, non-forested floodplains
do occur in the lower basins of some of the
major rivers, such as the Irrawaddy, Chao
Phraya and Mekong (Corlett, 2009), as exemplified in Figure 3.
The biota of both the river and the associated
floodplains and wetlands shows an ecological
association with the flood pulse, although this is
very under-researched (Dudgeon, 2000a). For
example, seasonal patterns of phytoplankton and
zooplankton are related to the monsoonal flood
pulse, with a high abundance in the dry season and
a low abundance in the wet season (due to washout, dilution and high turbidity), although interstream variation in response has been observed
(Dudgeon, 2000a). Fish abundance is also associated with the flood pulse, with generally higher
numbers during stronger monsoons. Along the
Mekong River, life cycles are synchronised with
the flow regime, with upstream breeding migrations occurring during the wet season and downstream migrations occurring when water levels
recede (Welcomme, 1979). Similarly, the inundated floodplains in Bangladesh provide important nurseries for larvae and juvenile fish species
and fish abundances are positively correlated with
flood extent (De Graaf, 2003). Indeed, in areas
with two monsoonal pulses (e.g. south India), fish
may reproduce twice (Dudgeon, 1992). Ecological associations with the flood pulse are not
restricted to aquatic organisms either; many species of deer that occur in Asia (e.g. Hydropotesinermis, Elaphurusdavidianus, Axis porcinus) use
or are even confined to the seasonally inundated
floodplains and riparian wetlands and some show
adaptations such as splayed or very large hooves
for grazing these habitats (Dudgeon, 2000a). The
increased discharge associated with the flood
pulse also influences water chemistry, such as ion
concentrations, salinity, turbidity and dissolved
organic matter, which is likely to have a significant ecological impact, although this remains
under-researched (Dudgeon, 1992).
While some associations between hydrology
and ecology are described, links between fluvial
processes and the vegetation of these systems
have received very little research attention,
despite the fundamental functional importance
of vegetation within river systems that has been
acknowledged elsewhere (e.g. Corenblit et al.,
2009a, 2009b). Existing studies have tended to
be piecemeal and site-specific, but these are
synthesized here from two perspectives: the role
of hydrological and geomorphological processes on vegetation and the active role of vegetation in modifying physical processes.
III Interactions between hydrology,
geomorphology and vegetation
in Southeast Asian rivers
and floodplains
1 Hydrological and geomorphological
impacts on riparian vegetation
Literature on riparian and wetland vegetation
within the region has been heavily focused
towards botanical descriptions without strong
associations with physical processes. However,
these descriptions do show linkages between
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Moggridge and Higgitt
723
vegetation and the flood pulse. Research on the
floodplains of the very large rivers is sparse.
Many of the largest rivers exhibit anabranching
planforms, which are some of the most complex
and least understood systems (Latrubesse,
2008), and while research on floodplain vegetation of the large, anabranching systems in the
Neotropics has shown complex mosaics of
floodplain wetlands associated with hydrological and geomorphological processes (e.g. Latrubesse, 2012; Stevaux et al., 2013; and
previously cited examples) only a few isolated
studies exist within the study region. A study
by Arias et al. (2012) on Tonle Sap Lake (part
of the Mekong system) drew linkages between
the mosaic of floodplain vegetation types,
which included gallery forest (i.e. riparian forest
that occurs in an environment that is otherwise
unable to support forest), flooded shrubland and
open water, with the duration of inundation in
wet, normal and dry years. Similarly, although
peripheral to the study region, vegetation within
the active zone of the braided Brahmaputra
(category B2 in Table 1) shows a succession
with elevation (and thus inundation): short seasonal grass was found 0.5–2 m above bar height,
taller grass and shrubs were found at 2.5 m, and
4 m high grass and trees were found up to 8 m
above bar height (Sarma, 2005). Observation
of vegetation on an in-channel island on the anabranching Irrawaddy (B3) also showed a distinction between vegetation type according to
inundation regime (Figure 3).
More detailed research has been conducted
on smaller meandering systems within the
region. The geomorphic complexity of the
floodplain of the meandering sections of the Fly
River (B1) (Papua New Guinea) shows specific
vegetation assemblages with different landforms and is comprehensively described by Rau
and Reagan (2009). Open canopy forests, composed of Pometia, Terminalia, Alstonia, Planchonia, Bischofia, Cananga and Nauclea are
found on scroll bars and crevasse splays, while
Campnosperma, Terminalia, Syzygium, Nauclea
and Myristica dominate in the lower-elevation
backswamps of the system. In parts of the floodplain that are permanently inundated, open
swamp woodland dominated by Melaleucacajuputi or Naucleaorientale or aquatic grassland
species occurs (see Rau and Reagan, 2009, for
full species list). Similarly, vegetation communities on the monsoonal Adelaide River floodplain (B1) in Australia showed distinctions
along a seasonally flooded elevation gradient:
Syzgium spp. and Nauclea spp. dominated
in areas not flooded by more than 1 m, while Melaleuca spp. dominated in areas flooded by 2 m of
water (Bowman and McDonough, 1991). These
studies exemplify the rich diversity of vegetation
that can occur within floodplain environments,
but this is generally unrecorded in the region.
Other botanical descriptions in the region
have mainly been confined to small swamp forests, without information on the river system.
For example, Yamada (1997) describes the
vegetation composition of freshwater swamp
in Burma and showed that areas that differ in
inundation have distinct tree communities;
patches that were only inundated during the
monsoon were dominated by Albiziaprocera
and Buteafrondosa, among others, while continuously inundated areas that only dry out for
a few weeks per year were dominated by
Xanthophyllum spp. and Dalbergiareniformis.
Similarly, in the small, equatorial catchment
of Nee Soon in Singapore, forest composition
was related to the magnitude of water-level
fluctuation and the intensity of disturbance
(Corner, 1978). Within the freshwater swamp
of Nee Soon, forest community composition
varied with flood extent: Palaquiumxanthochymum dominated in areas that were frequently
flooded; Xylopiafusca dominated at higher elevations that were less prone to inundation; and
Lophopetalummultinervia, Cratoxylumarborescens and Alstoniaspathulata occurred adjacent
to river channels, where physical disturbance
was greatest. A similar relationship between
elevation and vegetation composition is
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Progress in Physical Geography 38(6)
described in Kalimantan by MacKinnon et al.
(1996).
Many of the trees observed in these environments have adaptations, such as stilt or buttress
roots or pneumatophores, to tolerate inundation
(Page et al., 1999). Corlett (2009) suggests that
high flows in riparian zones may facilitate plant
dispersal (and thus play a significant role in the
life cycles of those species), but also adds that
studies on this are absent. In Borneo, the dominant tree of freshwater swamp, Dryobalanopsrappa, can reproduce vegetatively following
mechanical disturbance, which may play an ecological role in maintaining the tree populations
within the swamp, by complementing seed
regeneration (Yamada and Suzuki, 2004). While
this process requires significant further research,
the observation of a complementary role of sexual and asexual reproduction in floodplain trees
has synergies with the Salicaceae in northern
temperate floodplains. Asexual reproduction is
important in maintaining Salicaceae populations,
as seed establishment is tightly coupled to flow
regimes and thus exhibits high interannual variability (Barsoum, 2002; Mahoney and Rood,
1998). While there has been no research into the
life cycle of floodplain vegetation in Southeast
Asia, observation has shown that significant variation from ‘average’ hydrological conditions
can have an adverse effect. For example, vegetation on the floodplain of the Mekong is adapted
to a ‘normal’ wet season and substantially longer
floods can lead to die-off and rotting, which can
contribute to de-oxygenated conditions in the
system (Welcomme and Halls, 2004).
The above case studies all demonstrate the
importance of lateral connectivity between rivers and floodplain systems for vegetation communities. Studies on other taxa (discussed in
the previous section) further confirm the ecological importance of these exchanges. Following
a synthesis of tropical Asian river ecology focusing on fish and invertebrates, Dudgeon (1992)
asserts the ecological significance of these lateral
exchanges, suggesting that longitudinal models
such as the River Continuum Concept (RCC)
(Vannote et al., 1980) present an incomplete
description of these processes. Further to this,
research from the Neotropics has suggested that
the Flood Pulse Concept may be too simplistic
for very large floodplain systems: water may
enter the floodplain from a variety of pathways,
including rainfall, flooding of local tributaries,
groundwater and main channel exchanges, which
interact with the morphological complexity of
the floodplain to create a mosaic of different
hydrological conditions (Mertes et al., 1995).
This is concurrent with conceptual advances
from temperate regions, where frameworks have
extended from a continuum approach and consider river systems as mosaics of heterogeneous,
dynamic patches, encompassing lateral, longitudinal and vertical exchanges (e.g. Frissell et al.,
1986; Poole, 2002) and geomorphological processes (Thorp et al., 2006). Such models may
be useful frameworks for Southeast Asian systems, but this has not been tested to date.
2 The influence of vegetation on
hydrological and geomorphological
processes
The extensive variation in the size of rivers and
floodplains within Southeast Asia makes any
conceptual generalization of the active role of
vegetation problematic. Much existing regional
work in this field has been at the catchment
scale, where research has concentrated on the
impacts of large-scale deforestation, where
increases in river flow, stormflow, sediment
load and decreases in water quality and nutrients
have been observed following vegetation
removal (see Douglas, 1999, for a comprehensive review). In very large systems, vegetation
is unlikely to have a major direct geomorphic
role within the active zone, but large changes
in vegetation within the catchment can still be
hydrologically and geomorphologically significant. For example, within the Neotropics, studies of the Araguaia river catchment in Brazil
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Figure 4. Fallen trees, perpendicular to flow direction, create small jams and form step pools in the
Sungei Melinau Paku, Gunung Mulu National Park,
Sarawak, Malaysian Borneo.
(catchment area 375,000 km2, mean annual Q ¼
6500 m3 s-1), where 25% of the catchment has
been deforested, showed a 25% increase in
mean annual discharge from pre-deforestation
levels (Coe et al., 2011) and a 31% increase in bed
load transport (Latrubesse et al., 2009). This has
initiated a significant morphological response:
gullies have formed in the upper reaches of the
river, the number of islands in the channel has
decreased by 30%, the number of sandy bars
has risen substantially and the channel planform
has shifted from anabranching to braided
(Latrubesse et al., 2009). Thus, vegetation still
exerts a strong active control in very large
systems.
Within temperate systems, riparian vegetation has been shown to play an active role in
altering flow and sediment dynamics and influencing river planform (e.g. Gurnell et al., 2012).
Studies within Southeast Asia describe vegetation growing on braid bars (e.g. Brahmaputra,
Sarma, 2005; Fly, Pickup and Marshall, 2009)
and anabranch islands (e.g. Mekong, Gupta and
Liew, 2007, and observation of the Irrawaddy,
shown in Figure 3), but the potential active
role of this vegetation has not been explored.
A collection of studies from the region do
demonstrate an active role of vegetation, but
this is confined to the channel scale and is thus
only relevant to small river systems. At a patch
level, work has shown that riparian vegetation
alters the light, temperature and hydraulic conditions within small river channels, which influences the invertebrate communities present
(Dudgeon, 1989). Similarly, a study on the habitat requirements of fish on the floodplain wetlands of the meandering Mulgrave River in
northern Australia (B1) (catchment area 810
km2, mean annual Q ¼ approx. 50 m3 s-1)
showed that the riparian and in-channel vegetation supported the fish communities by creating
habitats which changed seasonally with the
flood pulse to meet the different requirements
of the fish at key stages of their life cycle
(Rayner et al., 2008).
Large wood deposited within river channels
can be an important influence on physical processes. For example, Figure 4 shows fallen trees
across a small channel in Sarawak, Borneo,
which have created a small jam and altered flow
patterns. Published work within the region also
demonstrates the importance of large wood. A
study of three small headwater streams in
Sabah, Malaysia (catchment area 0.5–10 km2),
showed that in small channels (i.e. a channel
width around 20 m where the channel can be
blocked by a single fallen log), tree fall was a
major influence on channel morphology and
processes (Spencer et al., 1990). Trees changed
the longitudinal profile of the channels by creating organic steps, with falls of 2–3 m in height.
The rate of rotting of the logs, lateral movement
of the channel and the magnitude of high flows
influenced the residence time of these jams,
which the authors suggest may be lower than for
temperate systems. Nonetheless, these jams
may still be morphologically important; in addition to the direct changes to the channel, the
jams collect and store sediment in minor and
moderate events and release it in major and
extreme events, increasing the importance of
high-magnitude, low-frequency events for the
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726
Progress in Physical Geography 38(6)
removal of fluvial sediment. These findings are
supported by observations of headwaters in the
forested Bukit Tarek catchment in Penninsula
Malaysia (A1) (catchment area 0.33 km2),
where 500–600 large wood accumulations per
ha of channel were observed, storing 20–40
m3 ha sediment (Gomi et al., 2006).
Within the typically nutrient-poor river systems of Southeast Asia, large wood can also
play an important role in retaining organic matter. Study of Neotropical streams has shown that
reduced hydraulic forces behind dams and the
accumulations of organic detritus provides
important shelter and food resources for a range
of animals, which promotes biodiversity (Wantzen and Junk, 2000).
In a global synthesis of the role of wood in
river systems, Gurnell (2013) compared the
storage of wood in tropical rivers, derived from
a small collection of studies from Central and
South America, to forest types in other ecoregions. Wood storage in rivers in tropical rainforest (mean 189 m3 ha-1, median 144 m3 ha-1) was
significantly less than for redwood or conifer
forest rivers, but significantly greater than
deciduous and Salicaceae dominated rivers. In
this comparison, Gurnell (2013) identifies two
factors which drive contrasts between wood
processes in different systems: (1) the wood
budget, i.e. the relative contribution and key
processes governing wood input, retention and
output within systems; (2) the ability of the
wood to regenerate. While the conclusions of
Spencer et al. (1990) from Borneo have not been
tested further within Southeast Asia, studies
from the wider tropics do suggest that further
research within this region could make an
important contribution to this field. For example, in an overview of tropical rainforests,
Walsh and Blake (2009) suggest that rainforest
vegetation may exert a greater role on channel
processes than in temperate zones and identify
this as a defining characteristic of tropical rivers. Further, Cadol and Wohl (2010) and Cadol
et al. (2009) make comparisons of wood budgets
between tropical and temperate river systems,
based on field studies in Costa Rican small
headwater streams (catchment area 0.1–8.5
km2). The studies showed that wood in the channel was transported from upstream sources
rather than occurring from local recruitment
(i.e. tree fall into the channel), which differed
to local recruitment-dominant temperate systems. Reduced wood loads and lower retention
times (mean residence time for a piece of wood
was 4.9 years) in tropical rivers compared to
temperate systems were also observed, which
the authors attribute to flashier flow regimes,
the branched structure of the trees and higher
decay rates in tropical environments. They also
infer that this may reduce the long-term geomorphological importance of wood jams in
these systems, which opposes Walsh and
Blake’s (2009) assertions and highlights the
need for further research in this field. Synergies
may be drawn between Southeast Asian and
Costa Rican systems, although the relative
importance of recruitment processes may differ
in Southeast Asia from what Cadol and Wohl
(2010) and Cadol et al. (2009) observed, on
account of the variation in storm and hurricane
frequency and intensity across the region.
Further to observations on the wood budget
in the Neotropics, Wantzen and Junk (2000)
found that large wood had the ability to regenerate roots and twigs, which further alters flow
patterns within the channel. While these observations are not within the study region, it is
entirely plausible that trees within Southeast
Asia may exhibit the same characteristics.
There is an acknowledged bias in large wood
studies from the temperate zone and a need to
expand understanding into different regions and
different river types (Collins et al., 2012; Gurnell, 2013). Existing studies from tropical rivers
do suggest a different morphological behaviour
of wood, but further work on Southeast Asian
river types, with different flow regimes and
sediment dynamics, could extend understanding
further.
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The studies discussed above demonstrate the
geomorphological importance of in-channel
vegetation. A study by Iwata et al. (2003) on the
headwaters of Rayu River in Malaysian Borneo
(discharge of study reaches ¼ 0.01–1.17 m3 s-1)
extends this by demonstrating that living riverbank vegetation can influence in-stream habitat.
The research investigated the impact of deforestation on invertebrate communities, but
included field observations of stream habitat
next to primary and secondary riparian forest.
Channels bordered by primary riparian forest
were characterized by coarser substrate, stable
banks, a greater proportion of erosional habitat
and less channel cover, while channels with secondary riparian forest had finer substrate, more
eroded banks, more depositional habitat and
more tree cover on the water. This suggests a
reach-scale influence of particular vegetation
communities on sediment dynamics, but the
landform-scale morphological importance of
this is not considered (as it was not an objective
of the study) and more detailed, directed studies
are needed to confirm and extend these findings.
This synthesis of existing studies demonstrates that vegetation has an active role in influencing geomorphological processes at the
channel and reach scale within the smaller river
systems in the region (such as type A1 identified
in Table 1). Work on in-channel large wood in
the wider tropical region indicates that processes of wood entrainment, storage, geomorphic influence and decay differ to
temperate systems, but further work in Southeast Asia is required. Research to date has
mainly focused on vegetation within the river
channel; the active role of vegetation on inchannel landforms, such as bars and islands, and
on floodplains and their wetlands has not been
explored, despite studies in temperate systems
that show the critical geomorphological importance of this (e.g. Corenblit et al., 2009b; Gurnell and Petts, 2006). This raises a number of
pertinent research questions for the region,
which are discussed in the following section.
IV Directions for future research
There is a clear deficit in understanding of the
interaction between vegetation and fluvial processes in Southeast Asian rivers and wetlands,
which is reflective of a wider absence of fluvial
geomorphological research within tropical systems (Walsh and Blake, 2009). In 1990, the
urgent need for the most basic descriptive and
inventory information on forested wetlands
within the region was recognized by Jusoff and
Majid. Subsequent progress has been very slow
(although see, for example, Yamada, 1997),
which highlights the extent of the knowledge
gap.
Existing descriptions of floodplain vegetation have shown a relationship between species
distributions and variations in the flood pulse,
which demonstrates the ecological importance
of inundation and connectivity in tropical floodplain systems and is synonymous with existing
concepts (e.g. Flood Pulse Concept, Junk
et al., 1989) and field studies from temperate
environments (e.g. Auble et al., 1994; Hupp and
Osterkamp, 1985; Johnson, 2000). However,
these studies lack a process-based explanation
for the observed vegetation distributions, which
raises important questions for future research.
Although the influence of water levels is
acknowledged, the ecological importance of
particular characteristics of the pulse (as
researched in Neotropical rivers and described
by Welcomme and Halls, 2004) is not understood. Further, with the exception of Rau and
Reagan’s (2009) work on the Fly River in Papua
New Guinea, studies from Southeast Asia have
not been extended to consider hydrogeomorphological processes. Current research from
temperate systems (e.g. Stanford et al., 2005;
Steiger et al., 2005) and the Neotropics (e.g.
Marchetti et al., 2013) has progressed from the
Flood Pulse Concept, suggesting that simple linear gradients of inundation are insufficient in
explaining vegetation patterns; vegetation patterns reflect hydrogeomorphological processes
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Progress in Physical Geography 38(6)
which create heterogeneous and dynamic habitat mosaics within the river landscape. The
applicability of these concepts to Southeast
Asian systems is an important and worthwhile
area for future research. Boulton et al. (2008)
rightly caution against an uncritical extrapolation of temperate models into tropical rivers and
any comparative work must be supported by
robust field evidence. This is particularly
important when the large anabranching systems
are considered; the majority of these occur
within the tropical latitudes (Latrubesse, 2008)
and with most models of vegetation dynamics
developed through research on smaller meandering or braided systems within temperate
zones (e.g. Stanford et al., 2005; Steiger et al.,
2005) such models may be inappropriate to
these systems. Similarly, while some of the
findings on vegetation in the large meandering
and anabranching systems of the Neotropics
may be relevant to equivalent systems within
Southeast Asia, the different flow regimes and
species within the Southeast Asian systems may
also create important differences which could
extend understanding in this field. Thus, there is
a need to explore these processes across all different types of river identified in Table 1 (and indeed
in river types that might not have been considered), in systems of different size, flow regime
and with different vegetation communities.
Understanding the ecological requirements
of riparian and wetland species and the association with physical processes at each stage of
their life cycle is also fundamental. These processes are well researched in temperate floodplains where models of vegetation, flow and
sediment interactions are applied to floodplain
management and conservation (e.g. Mahoney
and Rood, 1998; Richards et al., 2002). However, they are not currently understood in the
exceptionally biodiverse Southeast Asian systems, where such models could effectively support conservation in the region. Research is
needed on reproduction and initial establishment of the dominant floodplain species and the
significance of the flood pulse and associated
disturbance on influencing these processes.
There are indications from the literature that
vegetation actively influences fluvial processes
in Southeast Asian systems, as evidenced predominantly from studies of large wood within
small river channels. This specific field has
been well researched in temperate systems and
there is a widely acknowledged need for studies
in other ecoregions (Collins et al., 2012; Gurnell, 2013; Montgomery and Piégay, 2003).
As outlined in the previous section, there are
notable contrasts in wood processes between
river systems and further research in Southeast
Asia could make an important contribution to
global knowledge in this field, due to the different species, disturbances and wood decay rates
(Spencer et al., 1990). Research on the role of
wood in the medium and large systems is also
needed, as this has not been considered at all
in tropical systems.
The active role of vegetation in influencing
fluvial processes extends beyond the morphological changes within the channel (Gurnell et al.,
2012) and broad catchment-scale processes.
Research outside of the tropics has shown vegetation to have a major influence on fluvial morphology and processes across the floodplain, but
no existing research on this within Southeast
Asian systems or the wider tropics was found
in this synthesis. There is a pertinent need to
research how vegetation influences landform
growth, development and residence time at different scales and across river types in the region
(e.g. B1B3). Many of the very large rivers
within the region have established vegetation
within the active zone and the physical role of
this needs researching, as there have been very
few studies on large systems. Across all of the
river types and catchment sizes within the
region, the different species found in tropical
floodplains and wetlands, with their faster
growth and decay rates, coupled with the flow
regimes and high sediment loads of these systems, could provide new, fresh insights and
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Moggridge and Higgitt
729
potentially extend existing temperate-focused
models such as Corenblit et al. (2009a). With
tropical catchments covering the largest area
of the Earth’s climatic zones, there is a need
for more representative research on these
processes, rather than broad extrapolation of
temperate models into the area (Boulton
et al., 2008).
Southeast Asian systems are inherently very
variable, both in river types and in the large variation in size. Thus, it is problematic to make
wide generalizations about the interaction of
vegetation and fluvial processes and to what
extent existing models can be appropriately
applied. Boulton et al. (2008) also recognize this
and suggest that the extrapolation of (ecological) models may not be an issue of temperate
against tropical systems, but that the model
needs to be applied to an appropriate and comparable system. Similarly, direct comparison
between tropical and temperate systems does
not necessarily have to be the focus for further
research; empirical data on vegetation and fluvial processes must be the priority and this may
even yield new models in addition to advancing
global knowledge of these processes. This supports the argument made by Douglas (1993:
104) for a greater focus on research within tropical regions across the discipline of geography:
‘it is high time the whole world sees the tropics
as the ‘‘norm’’’.
Vegetation and hydrogeomorphological processes provide the physical habitat that underpins all the other biotas in this exceptionally
biodiverse environment. It supports the functional integrity of the ecosystem and thus its
long-term sustainability. The environment
within this region is undergoing rapid rates of
loss and human alteration (Dudgeon, 2000b),
with few rivers of Southeast Asia still in a natural state (Gupta, 2005). Therefore, in addition to
the academic value of this research, there is an
urgent need to understand these systems, to
support and inform effective conservation and
management.
Acknowledgements
H. Moggridge would like to thank the University of
Sheffield for funding this fellowship and the
National University of Singapore for their kind hospitality. Thanks also go to Paul Coles (University of
Sheffield) for his assistance with the production of
Figure 1 and to the two anonymous reviewers for
their helpful and constructive comments.
Funding
This publication was the product of a University of
Sheffield Faculty of Social Science Visiting Fellowship to the National University of Singapore.
References
Anderson JA (1983) The tropical peat swamps of western
Malaise. In: Gore AJ (ed.) Ecosystems of the World.
Amsterdam: Elsevier, 181–200.
Arias ME, Cochrane TA, Piman T, et al. (2012) Quantifying changes in flooding and habitats in the Tonle Sap
Lake (Cambodia) caused by water infrastructure
development and climate change in the Mekong Basin.
Journal of Environmental Management 112: 53–66.
Auble GT, Friedman JM and Scott ML (1994) Relating
riparian vegetation to present and future streamflows.
Ecological Applications 4: 544–554.
Barsoum N (2002) Relative contributions of sexual and
asexual regeneration strategies in Populus nigra and
Salix alba during the first years of establishment on a
braided gravel bed river. Evolutionary Ecology 15:
255–279.
Bendix J and Hupp CR (2000) Hydrological and geomorphological impacts on riparian plant communities.
Hydrological Processes 14: 2977–2900.
Bertoldi W, Drake NA and Gurnell AM (2011) Interactions between river flows and colonizing vegetation on
a braided river: Exploring spatial and temporal
dynamics in vegetation cover using satellite data. Earth
Surface Processes and Landforms 36: 1474–1486.
Boulton AJ, Boyero L, Covich AP, et al. (2008)Are tropical streams ecologically different from temperate
streams? In: Dudgeon D (ed.) Tropical Stream Ecology. Amsterdam: Elsevier, 257–284.
Bowman JL and McDonough L (1991) Tree species distribution across a seasonally flooded elevation gradient
in the Australian monsoon tropics. Journal of Biogeography 18: 203–212.
Downloaded from ppg.sagepub.com at PENNSYLVANIA STATE UNIV on May 13, 2016
730
Progress in Physical Geography 38(6)
Cadol D and Wohl E (2010) Wood retention and transport
in tropical headwater streams, La Selva Biological
Station, Costa Rica. Geomorphology 123: 61–73.
Cadol D, Wohl E, Goode JR, et al. (2009) Wood distribution in Neotropical forested headwater streams of La
Selva Costa Rica. Earth Surface Processes and Landforms 34: 1198–1215.
Coe MT, Latrubesse EM, Ferreira ME, et al. (2011) The
effects of deforestation and climate variability on the
streamflow of the Araguaia River, Brazil. Biogeochemistry 105: 119–131.
Collins BD, Montgomery DR, Fetherston KL, et al.
(2012) The floodplain large-wood cycle hypothesis:
A mechanism for the physical and biotic structuring
of temperate forested alluvial valleys in the North
Pacific coastal ecoregion. Geomorphology 139–140:
460–470.
Corenblit D, Steiger J, Gurnell AM, et al. (2009a) Plants
intertwine fluvial landform dynamics with ecological
succession and natural selection: Aniche construction
perspective for riparian systems. Global Ecology and
Biogeography 18: 507–520.
Corenblit D, Steiger J, Gurnell AM, et al. (2009b) Control of
sediment dynamics by vegetation as a key function
driving biogeomorphic succession within fluvial corridors. Earth Surface Processes and Landforms 34:
1790–1810.
Corenblit D, Tabacchi E, Steiger J, et al. (2007) Reciprocal
interactions and adjustments between fluvial landforms
and vegetation dynamics in river corridors: A review of
complementary approaches. EarthScience Reviews 84:
56–86.
Corlett RT (2009) The Ecology of Tropical East Asia.
Oxford: Oxford University Press.
Corner E (1978) The freshwater swamp-forest of south
Johore and Singapore. Gardens Bulletin Supplement
No1. Singapore: Botanic Gardens, Parks and Recreation Department.
Coulthard TJ (2005) Effects of vegetation on braided stream
pattern and dynamics. Water Resources Research 41:
W04003.
De Graaf G (2003) Dynamics of floodplain fisheries in
Bangladesh, results of 8 years fisheries monitoring in
the compartmentalization pilot project. Fisheries
Management and Ecology 10: 191–199.
Dettinger MD and Diaz HF (2000) Global characteristics
of stream flow seasonality and variability. Journal of
Hydrometeorology 1: 289–310.
Dietrich W, Day G and Parker G (1999) The Fly River,
Papua New Guinea: Inferences about river dynamics
floodplain sedimentation and fate of sediment. In:
Miller AJ and Gupta A (eds) Varieties of Fluvial Form.
Chichester: Wiley, 345–376.
Douglas I (1993) The tropics: Environments and
human impacts understood and reinterpreted. Singapore Journal of Tropical Geography 14(2):
103–122.
Douglas I (1999) Hydrological investigations of forest
disturbance and land cover impacts in Southeast Asia:
A review. Philosophical Transactions of the Royal
Society of London B 354: 1725–1738.
Dudgeon D (1989) The influence of riparian vegetation on
the functional organisation of four Hong Kong stream
communities. Hydrobiologia 179: 183–194.
Dudgeon D (1992) Endangered ecosystems: A review of
the conservation status of tropical Asian rivers.
Hydrobiologia 248: 167–191.
Dudgeon D (2000a) The ecology of tropical Asian rivers
and streams in relation to biodiversity conservation.
Annual Review of Ecological Systems 31: 239–263.
Dudgeon D (2000b) Large-scale hydrological changes in
tropical Asia: Prospects for riverine biodiversity.
Bioscience 50:793–806.
Fisher SG, Heffernan JB, Sponseller RA, et al. (2007)
Functional ecomorphology: Feedbacks between form
and function in fluvial landscape ecosystems. Geomorphology 89: 84–96.
Frissell CA, Liss WJ, Warren CE, et al. (1986) A hierarchical framework for stream habitat classification.
Environmental Management 10: 199–214.
Gomi T, Sidle RC, Noguchi S, et al. (2006) Sediment and
wood accumulations in humid tropical headwater
streams: Effects of logging and riparian buffers. Forest
Ecology and Management 224: 166–175.
Greet J, Angus Webb J and Cousens RD (2011) The
importance of seasonal flow timing for riparian vegetation dynamics: A systematic review using causal
criteria analysis. Freshwater Biology 56: 1231–1247.
Gupta A (2005) Rivers of Southeast Asia. In: Gupta A (ed.)
The Physical Geography of Southeast Asia. Oxford:
Oxford University Press, 65–79.
Gupta A (2011) Tropical Geomorphology. Cambridge:
Cambridge University Press.
Gupta A and Liew SC (2007) The Mekong from satellite
imagery: A quick look at a large river. Geomorphology
85: 259–274.
Downloaded from ppg.sagepub.com at PENNSYLVANIA STATE UNIV on May 13, 2016
Moggridge and Higgitt
731
Gupta A, Hock L, Huang XJ, et al. (2002) Evaluation of
part of the Mekong River using satellite imagery.
Geomorphology 44(34): 221239.
Gurnell A (2013) Wood in fluvial systems. In: Shroder JF
(ed.) Treatise on Geomorphology 9. San Diego: Academic Press, 163–188.
Gurnell A and Petts G (2006) Trees as riparian engineers:
The Tagliamento river, Italy. Earth Surface Processes
and Landforms 31: 1558–1574.
Gurnell AM, Bertoldi W and Corenblit D (2012) Changing
river channels: The roles of hydrological processes,
plants and pioneer fluvial landforms in humid temperate, mixed load, gravel bed rivers. Earth Science
Reviews 111: 129–141.
Gurnell A, Tockner K, Edwards P, et al. (2005) Effects of
deposited wood on biocomplexity of river corridors.
Frontiers in Ecology and the Environment 3: 377–382.
Hamilton SK, Kellndorfer J, Lehner B, et al. (2007)
Remote sensing of floodplain geomorphology as a
surrogate for biodiversity in a tropical river system
(Madre de Dios, Peru). Geomorphology 89: 23–38.
Hughes FMR (1990) The influence of flooding regimes on
forest distribution and composition in the Tana River
floodplain, Kenya. Journal of Applied Ecology 27:
475–491.
Hupp CR and Osterkamp WR (1985) Bottomland vegetation distribution along Passage Creek Virginia in
relation to fluvial landforms. Ecology 66: 670–681.
Iwata T, Nakano S and Inoue M (2003) Impacts of past
riparian deforestation on stream communities in a tropical rain forest in Borneo. Ecological Applications 13:
461–473.
Jain V, Tandon SK and Sinha R (2012) Application of
modern geomorphic concepts for understanding the
spatio-temporal complexity of the large Ganga river
dispersal system. Current Science 103(11): 1300–1319.
Johnson WC (2000) Tree recruitment and survival in rivers: Influence of hydrological processes. Hydrological
Processes 14: 3051–3074.
Junk WJ and Wantzen KM (2004) The Flood Pulse
Concept: New aspects, approaches and applications –
anupdate. In: Welcomme R and Petr T (eds) Proceedings of the Second International Symposium on the
Management of Large Rivers for Fisheries, Volume II.
Bangkok:Food and Agriculture Organization of the
United Nations, 117–140.
Junk WJ, Bayley PB and Sparks RE (1989) The floodpulse concept in river-floodplain systems. Special
Publication of the Canadian Journal of Fisheries and
Aquatic Sciences 106: 110–127.
Jusoff K and Majid M (1990) Inventory and monitoring of
forested–wetland resources of ASEAN. Forest Ecology
and Management 33–34: 63–79.
Kalliola R, Puhakka M, Salo J, et al. (1991) The dynamics,
distribution and classification of swamp vegetation in
Peruvian Amazonia. Annales Botanici Fennici 28:
225–239.
Keogh TM, Keddy PA and Fraser LH (1999) Patterns of
tree species richness in forested wetlands. Wetlands 19:
639–647.
King RT (2003) Succession and micro-elevation effects
on seedling establishment of Calophyllum brasiliense
camb (Clusiaceae) in an Amazonian river meander
forest. Biotropica 35: 462–471.
Lamotte S (1990) Fluvial dynamics and succession in the
lower Ucayali River basin, Peruvian Amazonia. Forest
Ecology and Management 33–34: 141–156.
Latrubesse E (2008) Patterns of anabranching channels:
The ultimate end-member adjustment of mega rivers.
Geomorphology 101: 130–145.
Latrubesse E (2012) Amazon lakes. In: Bengtsson L,
Herschy RW and Fairbridge RW (eds) Encyclopedia of
Lakes and Reservoirs. Encyclopedia of Earth Sciences
Series. Dordrecht: Springer,13–26.
Latrubesse EM, Amsler ML, Morais RP, et al. (2009) The
geomorphologic response of a large pristine alluvial
river to tremendous deforestation in the South American tropics: The case of the Araguaia River. Geomorphology 113: 239–325.
Latrubesse EM, Stevaux JC and Sinha R (2005) Tropical
rivers. Geomorphology 70: 187–206.
MacKinnon K, Hatta G, Halim H, et al. (1996) The Ecology of Kalimantan. Hong Kong: Periplus Editions.
Mahoney JM and Rood SB (1998) Steamflow requirements for cottonwood seedling recruitment – an integrative model. Wetlands 18: 634–645.
Marchetti ZY, Latrubesse EM, Pereira MS, et al. (2013)
Vegetation and its relationship with geomorphologic
units in the Parana River floodplain, Argentina. Journal
of South American Earth Sciences 46: 122–136.
Medley KE (1992) Patterns of forest diversity along the
Tana River, Kenya. Journal of Tropical Ecology 8:
353–371.
Mertes LAK, Daniel DL, Melack JM, et al. (1995) Spatial
patterns of hydrology, geomorphology, and vegetation on the floodplain of the Amazon River in Brazil
Downloaded from ppg.sagepub.com at PENNSYLVANIA STATE UNIV on May 13, 2016
732
Progress in Physical Geography 38(6)
from a remote sensing perspective. Geomorphology
13: 215–232.
Montgomery DR and Piégay H (2003) Wood in rivers:
Interactions with channel morphology and processes.
Geomorphology 51(1–3): 1–5.
Ng PKL and Lim KKP (1992) The conservation status of
the Nee Soon freshwater swamp forest of Singapore.
Aquatic Conservation: Marine and Freshwater Ecosystems 2: 255–266.
Page SE, Rieley JO, Shotyk OW, et al. (1999) Interdependence of peat and vegetation in a tropical peat
swamp forest. Philosophical Transactions of the Royal
Society of London B 354: 1885–1897.
Page SE, Rieley JO and Wust R (2006) Lowland tropical
peatlands of Southeast Asia. In: Martini IP, Martinez A
and Chesworth W (eds) Peatlands: Evolution and
Records of Environmental and Climate Changes.
Amsterdam:Elsevier, 145–172.
Perucca E, Camporeale C and Ridolfi L (2007) Significance of the riparian vegetation dynamics on
meandering river morphodynamics. Water Resources
Research 43: W03430.
Pickup G (1984) Geomorphology of tropical rivers 1:
Landforms, hydrology and sedimentation in the Fly and
lower Purari, Papua New Guinea. In: Schick AP (ed.)
Channel Processes: Water, Sediment and Catchment
Controls. Catena Supplement 5. Reiskirchen: Catena,
1–17.
Pickup G and Marshall AR (2009) Geomorphology,
hydrology and climate of the Fly River system. In:
Boulton BR (ed.) The Fly River, Papua New Guinea:
Environmental Studies in an Impacted Tropical River
System. Development in Earth and Environmental
Sciences 9. Amsterdam: Elsevier, 3–47.
Poole GC (2002) Fluvial landscape ecology: Addressing
uniqueness within the river discontinuum. Freshwater
Biology 47: 641–660.
Puckridge JT, Sheldon F, Walker KF, et al. (1998) Flow
variability and the ecology of large rivers. Marine and
Freshwater Research 49: 55–72.
Rau MT and Reagan DP (2009) Vegetation of the Ok TediFly River system. In: Bolton BR (ed.) The Fly River,
Papua New Guinea: Environmental Studies in an
Impacted Tropical River System. Amsterdam: Elsevier,
515–548.
Rayner TS, Pusey BJ and Pearson RG (2008) Seasonal
flooding, instream habitat structure and fish assemblages in the Mulgrave River, north-east Queensland:
Towards a new conceptual framework for understanding fish-habitat dynamics in small tropical rivers.
Marine and Freshwater Research 59: 97–116.
Richards K, Brasington J and Hughes F (2002) Geomorphic dynamics of floodplains: Ecological implications and a potential modelling strategy. Freshwater
Biology 47: 559–579.
Sarma JN (2005) Fluvial process and morphology of the
Brahmaputra River in Assam, India. Geomorphology
70: 226–256.
Spencer T, Douglas I, Greer T, et al. (1990) Vegetation and
fluvial geomorphic processes in south-east Asian tropical rainforests. In: Thornes J (ed.) Vegetation and Erosion. Chichester: Wiley, 451–469.
Stamp LD (1940) The Irrawaddy River. The Geographical
Journal 5: 329352.
Stanford JA (1998) Rivers in the landscape: Introduction to
the special issue on riparian and groundwater ecology.
Freshwater Biology 40: 402–406.
Stanford JA, Lorang MS and Hauer FR (2005) The shifting
habitat mosaic of river ecosystems. Verhandlungen der
Internationale Vereinigung fur Theoretische und
Angewandte Limnologie 29: 123–136.
Steiger J, Tabacchi E, Dufour S, et al. (2005) Hydrogeomorphic processes affecting riparian habitat within
alluvial channel–floodplain river systems: A review for
the temperate zone. River Research and Applications
21: 719–737.
Stevaux JC, Corradini FA and Aquino S (2013) Connectivity processes and riparian vegetation of the upper
Parana River, Brazil. Journal of South American Earth
Sciences 46: 113–121.
Tabacchi E, Lambs L, Guilloy H, et al. (2000) Impacts of
riparian vegetation on hydrological processes. Hydrological Processes 14: 2959–2976.
Tal M, Gran K, Murray A-B, et al. (2004) Riparian vegetation as a primary control on channel characteristics in
multi-thread rivers. In: Bennet SJ and Simon A (eds)
Riparian Vegetation and Fluvial Geomorphology.
Water Science and Application 8. Washington, DC:
American Geophysical Union, 43–58.
Thorp JH, Thoms MC and Delong MD (2006) The riverine
ecosystem synthesis: Biocomplexity in river networks
across space and time. River Research and Applications 22: 123–147.
Tockner K, Malard F and Ward JV (2000) An extension of
the flood pulse concept. Hydrological Processes 14:
2861–2883.
Downloaded from ppg.sagepub.com at PENNSYLVANIA STATE UNIV on May 13, 2016
Moggridge and Higgitt
733
Tooth S and Nanson GC (1999) Anabranching rivers on
the Northern Plains of arid central Australia. Geomorphology 29: 211–233.
Tooth S and Nanson GC (2000) The role of vegetation in
the formation of anabranching channels in an ephemeral river, northern plains, arid central Australia.
Hydrological Processes 14: 3099– 3117.
Vannote RL, Minshall GW, Cummins KW, et al. (1980)
The river continuum concept. Canadian Journal of
Fisheries and Aquatic Sciences 37: 130–137.
Walsh RPD and Blake WH (2009) Tropical rainforests. In:
Slaymaker O, Spencer T and Embleton-Hamann C
(eds) Geomorphology and Global Environmental
Change. Cambridge: Cambridge University Press,
214–247.
Wantzen KM and Junk WJ (2000) The importance of
stream-wetland-systems for biodiversity: A tropical
perspective. In: Gopal B, Junk WJ and Davis JA (eds)
Biodiversity in Wetlands: Assessment Function and
Conservation. Leiden: Backhuys, 11–34.
Welcomme R (1979) Fisheries Ecology of Floodplain
Rivers. London: Longman.
Welcomme R and Halls A (2004) Dependence of tropical
river fisheries on flow. In: Welcomme R and Petr T
(eds) Proceedings of the Second International Symposium on the Management of Large Rivers for Fisheries,
Volume II. Bangkok: Food and Agriculture Organization of the United Nations, 267–283.
Yamada T (1997) Tropical Rain Forests of Southeast Asia:
A Forest Ecologist’s View. Honolulu: University of
Hawaii Press.
Yamada T and Suzuki E (2004) Ecological role of vegetative sprouting in the regeneration of Dryobalanopsrappa, an emergent species in a Bornean tropical
wetland forest. Journal of Tropical Ecology 20:
377–384.
Downloaded from ppg.sagepub.com at PENNSYLVANIA STATE UNIV on May 13, 2016