Floodplain connectivity, disturbance and change: a palaeoentomological investigation of floodplain ecology from south‐west England

Abstract

Summary 1.Floodplain environments are increasingly subject to enhancement and restoration, with the purpose of increasing their biodiversity and returning them to a more 'natural' state. Defining such a state based solely upon neoecological data is problematic and has led several authors to suggest the use of a palaeoecological approach. 2. Fossil Coleopteran assemblages recovered from multiple palaeochannel fills in south-west England were used to investigate past floodplain and channel characteristics during the mid-to late-Holocene. Ordination of coleopteran data was performed using Detrended Correspondence Analysis (DCA) and produced clear and discrete clustering. This clustering pattern is related to the nature of the environment in which assemblages were deposited and hence channel configuration and dynamics. 3. The DCA clustering pattern is strongly related to measures of ecological evenness, and a strong relationship between these indices and the composition of the water beetle assemblage within samples was revealed. Repeating the ordination with presenceabsence data results in a similar pattern of clustering, implying that assemblage composition is crucial in determining cluster placement. 4. As assemblage composition is primarily a function of floodplain topography and hence disturbance regime, we attempt to relate these data to the Intermediate Disturbance Hypothesis (IDH). A significant positive correlation was found between ecological diversity (Shannon's H ′ ) and Axis 1 of all ordinations in predominantly aquatic assemblages.

Logjam controls on channel:floodplain interactions in wooded catchments and their role in the formation of multi-channel patterns

“…In turn this influences opportunities for seed dispersal and vegetation colonization and succession . Rare invertebrate and amphibian communities occupy the temporary pools found in floodplain channels and pools resulting in high biodiversity (Nicolet, 1997;Davis et al, 2007), whilst perennial secondary channels are important nursery habitat for juvenile salmonids (Beechie et al, 2005). The resulting dynamic floodplain patchwork is analogous to the Shifting Habitat Mosaic that Table 3 Comparisons between different metrics of channel pattern.…”

“…characterizes large piedmont alluvial floodplains and is associated with high biodiversity (Stanford et al, 2005;Davis et al, 2007). Similarly, Beechie et al (2006) have associated laterally stable channels with low biodiversity as a result of the low turnover rates of floodplain material.…”

Reconstructing riverine paleo-flow regimes using subfossil insects (Coleoptera and Trichoptera): the application of the LIFE methodology to paleochannel sediments

“…Potamonectes depressus elegans and Platambus maculatus), they are usually associated with slow flowing and lentic conditions (Lemdahl 2000;Smith et al 2001). Despite this limitation, their value as indicators of riverine landscape evolution and disturbance events associated with flooding has been increasingly acknowledged (Davis et al 2007;Smith and Howard 2004). …”

“…Subsequently, Coleoptera fauna have been associated with river discharge within low-gradient alluvial systems (Smith and Howard 2004), and they have been used to investigate floodplain connectivity and disturbance events (e.g. floods) within riverine sedimentary sequences (Davis et al 2007). …”

Ecohydrology on the edge: interactions across the interfaces of wetland, riparian and groundwater‐based ecosystems

“…In many anthropogenically modified systems, it may only be possible to achieve this with reference to past (palaeo) communities. These approaches have been pioneered within lake systems over a number of years (Bennion et al, 2011) and have begun to find wider application in studies of riparian and lotic ecosystems (Davis et al, 2007;Howard et al, 2010). With further inter-disciplinary endeavour the approach and methodologies proposed have application to other freshwater and wetland ecosystems.…”