Riverine landscapes: Biodiversity patterns, disturbance regimes, and aquatic conservation

“SH = shredders, FC = collector-filterers, GC = collector-gatherers, GS = grazers-scrapers, PR = predators stream management is needed to maintain or restore freshwater biodiversity, our study supports the idea that action plans should be designed at a landscape scale (Ward 1998).”

“Rivers play a vital role in the Earth’s hydrological, biological, and geomorphological processes Corresponding author: _Inci Güneralp, Texas A&M University, 810 Eller O&M Building, College Station, TX 77843, USA Email: iguneralp@geos.tamu.edu (e.g. Poole, 2002; Ward, 1997).”

“Specifically, landscape patterns related to disturbance, fragmentation, buffers, and land cover change have been shown to affect the abundance of rare and endangered species, levels of biodiversity, potential for invasion by exotic plants, habitat for birds, amphibians and other animals, water quality, and in-stream h…”

“The biodiversity of riverine ecosystems is closely related to habitat composition and habitat development, which are primarily controlled by natural fluvial disturbances (Ward 1998; Tockner et al. 2006).”

“Abandoned channels are recognized as large, structurally diverse features in floodplains (Bornette and others 1998; Ward 1998), and associations between abandoned channels and pioneer tree species have been emphasized in previous studies (Kalliola and others 1991; Shankman 1991, 1993; Cordes and…”

“As riparian and riverine habitats are amongst the most diverse yet threatened ecosystems world-wide (ECE – River Convention, 1992), they in particular deserve conservation attention (Ward, 1998; Naiman et al., 2005).”

“They are very sensitive to human induced activities and changes that transform their characteristics (Leuven & Poudevigne, 2002; Ward, 1998).”

“…challenging, given that their biodiversity is affected by (i) longitudinal processes along the stream size gradient, (ii) lateral interactions with the surrounding landscape, and (iii) within-stream vari- ability at the scale of stream sections and microhabitats (Allan, 1995; Ward, 1998).”

“These environments are essential resources for development (Ward 1998; Crisman et al. 2003) and face ever-increasing pressure especially in arid countries where freshwater is disproportionately important to humans and other species (Barnard and Shikongo 2000; Day 2003).”

“become “terrestrialized” by acquiring similar features to nearby soils (Figure 1a; Elosegi et al., 2010; Morandi et al., 2014; Thorp et al., 2006; Ward, 1998; Ward et al., 1998).”

“These disturbances operate over a broad range of spatial and temporal scales, and favour the development of complex mosaics of varying habitats that exhibit a wide spectrum of ecological succession (Minshall et al., 1985; Petts and Amoros, 1996; Ward, 1998; Tockner et al., 2000a).”

“River networks are particularly susceptible to fragmentation and habitat loss caused by anthropogenic activities (Ward 1998).”

“Accounting for landscape-scale spatial dynamics may significantly improve predictive models of the response of stream species to habitat perturbation (Fausch and others 1988, Harding and others 1998, Ward 1998).”

“Side arms, dead side arms, separated meander segments, and expansive floodplains, as they naturally appear in the lowland reach of a river, create a broad range of lotic, lentic, and semiaquatic habitats, leading to hot spots of biodiversity (37).”

“…is consistent with the known effects of dams and is related to restrictions on the downstream supply of fine sediments that deposit in the reservoir above the dam and increased scouring of sediments from the channel below the dam by hydropeaking operations (Ward, 1998; Stanford and Ward, 2001).”

“My results suggest a complex geomorphological structure of the riparian landscape with many interacting environmental factors (e.g. Frissell et al. 1986; Ward 1998; van Coller et al. 2000).”

“organisms with only restricted possibilities to respond to global environmental problems such as changes to climate and land use (Ward, 1998).”

“In many aquatic systems, changes to flow regimes are the major disturbance that influences biotic communities (Walker & Thoms, 1993; Ward, 1998).”

“CDMetaPOP was specifically developed for species living in dynamic riverine landscapes (‘riverscapes’; Ward 1998; Fausch et al. 2002).”

“…integrity of floodplain rivers is mainly defined by the extent of the intersection between geomorphology and hydrology, resulting in a reachspecific level of habitat diversity, and habitat characteristics (Junk et al., 1989; Bayley, 1995; Ward & Stanford, 1995; Ward, 1998; Schiemer et al., 2000).”

“Natural sinuosity is an important characteristic of river morphology, and it also forms a rich variety of river habitat [34].”

“…important to take into account the presence of natural potential barriers to dispersal (e.g., waterfalls) as well as other key riverscape variables (Ward 1998), such as elevation, channel width, and waterway distance, which have been shown to impact the distribution of genetic diversity in…”

“2002), the interest in better planning of protected areas aimed at freshwater wildlife conservation is increasing (Allan and Flecker 1993; Ward 1998; Lowe 2002).”

“waters and ground water (Ward, 1998).”

“However, many studies have highlighted the importance of linear structures such as riverine landscapes (Ward, 1998; Stohlgren et al., 2005), green lanes (Croxton et al., 2005), roads (Saarinen et al., 2005) and field edges (Croxton et al., 2002; Meek et al., 2002).”

“Describing riverine landscape and its relation to biodiversity patterns and disturbances, Ward (1998) observed that the river channels are part of an extensive interconnected series of biotopes and environmental gradients that together with their biotic communities constitute lotic ecosystems.”

“…floodplain ecosystem is typical of many other floodplain ecosystems and is under the strong physical control of the annual flood cycle (Bayley, 1995; Ward & Stanford, 1995; Ward, 1998; Ward et al., 1998; Tockner et al., 2000; Sommer et al., 2001, 2004; Baranyi et al., 2002; Schemel et al., 2004).”

“However, anthropogenic modification of flow regimes can alter the degree of lateral hydrological connectivity (hydrological transport onto the floodplain), resulting in altered soil nutrients, generating bare substrate and stressing established plants (Naiman and Décamps 1997; Ward 1998).”

“In this latter case, the clearest and most obvious explanation for increased richness in mountain regions at 20‐40∞N and elsewhere is that richness in river environments requires not only productive environments, but also geomorphologically complex riverine landscapes, in areas of high relief, with their associated di…”

“Floods spatially reorganize the resource template by redistributing nutrients and sediments into new biophysical patches (Ward 1998), influencing habitat available to plants (Kalliola et al.”

“When exploring relationships between flooding events and riparian diversity, researchers often use proxies for flood disturbance (Ward 1998).”

“Essas alterações diminuem a riqueza local porque homogeneizam os ambientes, diminuindo a disponibilidade de recursos e, criam ilhas de habitats que têm sua recolonização dependente da distância de outros habitats mais adequados (O’CONNOR 1991, ZWICK 1992, WARD 1998).”

“For example, in most streams and their adjacent riparian forests, habitat has been altered by two human activities, straightening channels (channelization) and removing riparian vegetation (Allan and Flecker 1993; Naiman and Décamps 1997; Ward 1998).”

“Ward (1998) reviews recent advances in the conceptual development of river ecology.”

“Floodplain rivers have always been highly valued environments for people in terms of settlement and exploitation (Ward, 1998; Junk & Wantzen, 2004; Winemiller, 2004; Jackson et al., 2005) and hence are impacted by multiple stressors (Tockner et al., 2010).”

“Whilst a few equate biodiversity with species richness (e.g., Ward, 1998), most accept that biodiversity in- corporates far more, but there is no universally agreed definition.”

“Increasing drought and flood intensity are liable to be met by greater human interventions in both river flow regime and morphology, in the form of intensified water abstraction/regulation for human use or engineering for flood prevention (Vaughan et al., 2009; Ward, 1998).”

“…the underlying geology, shaping the Handling editor: Sidinei Magela Thomaz A. L. dos Santos Fonseca Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Rua Carlos Wenceslau, 343, Rio de Janeiro, RJ CEP 21715-000, Brazil A. L. dos Santos Fonseca I. Bianchini Jr. Programa…”

“Floods spatially reorganize the resource template by creating patches and redistributing nutrients, sediments and propagules (Ward, 1998), which afterwards are available to a variety of plants (Kalliola et al., 1991).”

“Flow regimes, river connectivities (mainly with flood plains) and ecology of fluvial corridors became the main concerns [40].”

“The river flows determine the distribution patterns of back swamps, marshes and tributaries that make up the floodplain (Ward 1998).”

“regimes (Ward 1998), or combinations of the two”

“Structures along the rivers to stabilize the stream bed and reduce sediment movement became necessary due to the incision of major rivers (Ward 1998; Mauch & Zeller, 2008).”

“, 2004), natural expansion and contraction dynamics (sensu Stanley, Fisher, & Grimm, 1997) are influenced by human alterations to riverine landscapes (“riverscapes” hereafter; Ward, 1998).”

“The formation of oxbow lakes fundamentally changes local and regional ecosystem structure and processes [Knight and Welch, 2004; Ward, 1998], but less is known about changes to intrameander hyporheic exchange structure and processes during meander evolution through neck cutoff.”

“The riverine landscape is increasingly viewed as a ‘‘riverscape,’’ a term coined by Ward (1998).”

“Changes to the natural disturbance regime provided by flow regulation and the introduction of exotic taxa and landuse practices have all suppressed the natural environmental heterogeneity in riverine landscapes, resulting in dramatic impacts on biodiversity and ecological processes in rivers (Ward, 1998).”

“Flood channels, backswamps, braids, marshes, distributaries, billabongs and wetlands make up the floodplain of a large lowland river ( Ward, 1998 ).”

“…small scale measures and solutions and neglect that stream ecosystems are strongly governed by catchment scale processes (Allan, 2004; Palmer, 2010; Ward, 1998; Wiens, 2002; Sundermann and Stoll, 2011; P.C. dos Reis Oliveira et al. Journal of Environmental Management 264 (2020) 110417 Kuglerov�a…”

“Anthropogenic disturbances can intervene in the hydrological patterns of the basin (Ward, 1998) and modify the physical attributes of the aquatic habitat (Karr, 1981; Melo et al., 2003), which include such biological features (Maddock, 1999) as its riparian vegetation.”

“Flood disturbances are an integral component of active floodplain ecosystems ( Ward, 1998 ) and are considered as fundamental for the maintenance of biodiversity (Adis & Junk, 2002).”

“It is recognized that riparian zones and fringing floodplains form an integral part of a river ecosystem and contribute functionally to the overall integrity of these systems (see Ward 1998).”

“Ward (1998) described the pathways by which landscape disturbances organize and constrain instream habitats.”

“At the catchment scale, montane flood plains, typically located in the middle reaches of river systems, are the richest in plant and animal species (Tabacchi et al., 1998; Ward, 1998) likely owing to intermediate levels of flood disturbance (sensu Connell, 1978; Ward and Stanford, 1983).”

“Studies on the effects of river regulation support the thesis that a reduction in channel-forming floods is one of the primary causes of a decline in macroinvertebrate diversity downstream from dams (e.g., Ward 1998).”

“…and (2) the river system should maintain sufficient hydrological dynamism to allow erosive and overbank floods to occur, in order to entrain and deposit trees, to deposit propagules and organic materials, and to form scour features (e.g. Ward 1998; Gurnell et al. 2002; Pettit and Naiman 2005).”

“Both of these analyses are described in detail in Welsh et al. (2005). Results of these analyses provided subsets of independent variables used to build models for predicting the occurrence of the different herpetofaunal assemblages found in the Mattole (see below).”

“…1997), aquatic macrophyte loss (Körner, 1997), habitat loss (Jansen and Healey, 2003), eutrophication (Morris et al., 2003) and river regulation (Ward, 1998) on shallow lakes is well recognized, the historical development of such processes has typically been poorly monitored and understood,…”

“The challenge for the future lies in protecting the ecological integrity and biodiversity of aquatic systems in the face of increasing pressures on freshwater resources (Ward, 1998).”

“Natural disturbance regimes and environmental gradients are required to maintain river–flood plain connectivity and habitat heterogeneity (Sparks et al. 1990; Ward 1998).”

“The ecological health and integrity of floodplain waterbodies, including those supporting Taxodium-Nyssa stands, are directly influenced by their hydrological connectivity with the active main stem river (Poff et al., 1997; Ward, 1998).”

“Over the recent past we have learned that these systems perform multiple functions, which heavily depend on climate, catchment area, habitat structure and diversity, trophy, and several other factors (Ward, 1998; Arscott et al., 2000; Tockner et al., 2002).”

“However, human-induced alterations in watersheds caused by clearing of forests, increased agriculture, overgrazing, urbanization and modification of stream channels can profoundly disrupt natural function, transport massive quantities of material downstream (Ward 1998), and deliver increasing amounts of pollutants to…”