Characterization of large wood and its relationship to pool formation and macroinvertebrate metrics in southeastern coastal plain streams, USA

Abstract

Large wood has important structural and functional roles in streams but there is little information on large wood dynamics in the southeastern coastal plains, USA. In this study, we surveyed 35 streams in the Choctawhatchee River watershed of southeastern Alabama. These streams were broadly classified into three categories based on land use: urban, forest, and mixed (agriculture plus forest). The number, volume, and functions of large wood were quantified. Pool number, pool spacing, and drainage areas of each stream were measured along with assessment of macroinvertebrate assemblages. Large wood number and volume plus pool number and spacing were used to examine the relationship among large wood characteristics and functions, pool characteristics, drainage area, and attributes of macroinvertebrate assemblages including species richness, Shannon-Wiener diversity (H 0 ), number of Ephemeroptera, Plecoptera, and Trichoptera (EPT) species, and the Invertebrate Community Index (ICI -a multimetric index that reflects biological integrity of streams). There were significant differences in large wood number and volume among the three different stream categories, with highest large wood number and volume in forest streams. More pools and storage sites for sediment and organic matter were found in forest streams than urban and mixed streams. Large wood appeared to be positively related to macroinvertebrate assemblages, as species richness, H 0 , EPT, and ICI were generally higher in forest streams as compared to those of urban and mixed streams. The outcome of this study suggests that large wood contributes to the physical and biological complexity of streams in the southeastern coastal plain streams of the USA.

Serial discontinuity in naturally alternating forest and floodplain habitats of a Michigan (USA) stream based on physicochemistry, benthic metabolism, and organismal assemblages

“…The increase in taxa richness among both benthic macroinvertebrate and adult caddisfly faunas at forest sites suggested the importance of habitat heterogeneity in promoting biological diversity. Many studies have noted a link between macroinvertebrate taxa richness and increased in-stream coarse woody debris due to its use as a food source and shelter, area for biofilm colonization, ability to stabilize stream banks and channels, and indirect effects on habitat variability (Rios and Bailey 2006, Urban et al 2006, Schneider and Winemiller 2008, Houghton et al 2011, Stewart et al 2012, Pilotto et al 2014. In our study, site 6 had the highest amount of both woody debris and species richness, adding further support to the idea.…”

All Logjams Are Not Created Equal

“…Where riparian forests shade a substantial portion of the channel and limit photosynthesis, POM introduced from the floodplain forms the foundation of the aquatic ecosystem’s trophic cascade (Tank et al., 2010) and retention of POM for even a few hours can substantially increase the availability of nutrients to microbial and macroinvertebrate communities (Battin et al., 2008). Backwater and scour pools, overhead cover, and organic substrate associated with logjams provide important habitat for aquatic organisms (Herdrich et al., 2018; Richmond & Fausch, 1995; Stewart et al., 2012) and logjams in abandoned channels that have accreted to the floodplain provide habitat for terrestrial organisms (Harmon et al., 1986; Pettit et al., 2005). Logjams increase pressure gradients within the channel that enhance hyporheic exchange flows (Doughty et al., 2020; Hester & Doyle, 2008; Sawyer et al., 2011) and logjams obstruct flow and enhance overbank flow and lateral channel migration, thus enhancing channel‐floodplain connectivity (Collins et al., 2012; Jeffries et al., 2003; Wohl, 2011).…”

“…Where riparian forests shade a substantial portion of the channel and limit photosynthesis, POM introduced from the floodplain forms the foundation of the aquatic ecosystem's trophic cascade (Tank et al, 2010) and retention of POM for even a few hours can substantially increase the availability of nutrients to microbial and macroinvertebrate communities (Battin et al, 2008). Backwater and scour pools, overhead cover, and organic substrate associated with logjams provide important habitat for aquatic organisms (Herdrich et al, 2018;Richmond & Fausch, 1995;Stewart et al, 2012) and logjams in abandoned channels that have accreted to the floodplain provide habitat for terrestrial organisms (…”

Geomorphic effects of natural flood management woody dams in upland streams

“…The NFM woody dams in the upper River Cover catchment resulted in pool formation in some study reaches and accumulation of finer sediments in others. Previous research has suggested that the diversity of channel units (Hilderbrand, Lemly, Dolloff, & Harpster, 1997; Stewart, Bhattarai, Mullen, Metcalf, & Reátegui‐Zirena, 2012) and sediment facies (Doeg, Marchant, Douglas, & Lake, 1989; Mathers, Rice, & Wood, 2017) can contribute to increases in local biodiversity. Further studies are necessary to investigate if this increased in‐stream habitat diversity has indeed led to the presence of more diverse ecosystems.…”