Dynamics of Plains Cottonwood (Populus deltoides) Forests and Historical Landscape Change along Unchannelized Segments of the Missouri River, USA

Demographic response of Piping Plovers suggests that engineered habitat restoration is no match for natural riverine processes

“…On the Missouri River, a byproduct of managing for flood control has been the dramatic alteration of the ecosystem, leading to decreases in a variety of taxa, primarily due to habitat loss (U.S. Fish and Wildlife Service 2003, Dixon et al 2012, Johnson et al 2015. When the Missouri River flooded in 2010 and 2011, there was extensive damage to human infrastructure (NOAA 2012), but the floodwaters also increased the amount of Piping Plover nesting habitat substantially, contributing to a decline in nesting densities and increases in almost all measured demographic rates.…”

“…This river was historically dynamic, exhibiting 2 flow pulses per year that coincided with snow melt in the Great Plains, and in the mountains (Hesse andMestl 1993, Galat andLipkin 2000). Between 1937 and 1964 the U.S. Army Corps of Engineers (USACE) constructed 6 dams on the main stem of the river and channelized much of the lower Missouri River (U.S. Army Corps of Engineers 2006), which reduced flood frequency and suppressed within-year flood pulses (Hesse andMestl 1993, Galat andLipkin 2000), and ultimately resulted in a decrease of 96% of Missouri River sandbar habitat (Dixon et al 2012). The current water management regime has resulted in fewer flood events and has led to a decrease in habitat for a suite of species including the Piping Plover (Charadrius melodus), Least Tern (Sternula antillarum), pallid sturgeon (Scaphirhynchus albus), and plains cottonwood (Populus deltoides; U.S. Fish and Wildlife Service 2003, Dixon et al 2012, Johnson et al 2015.…”

“…Between 1937 and 1964 the U.S. Army Corps of Engineers (USACE) constructed 6 dams on the main stem of the river and channelized much of the lower Missouri River (U.S. Army Corps of Engineers 2006), which reduced flood frequency and suppressed within-year flood pulses (Hesse andMestl 1993, Galat andLipkin 2000), and ultimately resulted in a decrease of 96% of Missouri River sandbar habitat (Dixon et al 2012). The current water management regime has resulted in fewer flood events and has led to a decrease in habitat for a suite of species including the Piping Plover (Charadrius melodus), Least Tern (Sternula antillarum), pallid sturgeon (Scaphirhynchus albus), and plains cottonwood (Populus deltoides; U.S. Fish and Wildlife Service 2003, Dixon et al 2012, Johnson et al 2015. In response, the USACE initiated ecosystem management specifically to recover these species and from 2004 to 2009 created 255 ha of emergent sandbar habitat for Piping Plovers and Least Terns (U.S. Wildlife Service 2000, 2003).…”

Evidence of increase in woody vegetation in a river corridor, Northwest England, 1984–2007

“…Likewise, vegetation changes have been studied both in riverine and other environments, many studies using satellite imagery (Bertoldi, Drake, & Gurnell, 2011) but many, especially on decadal timescales, have used aerial photographs, as here (Dixon & Johnson, 1999;Garófano-Gómez et al, 2013;Gonzalez, Gonzalez-Sanchis, Cabezas, Comin, & Muller, 2010;Kondolf, Piegay, & Landon, 2007;Lunt, Winsemius, McDonald, Morgan, & Dehaan, 2010;Yang & Tien, 2010). Increases in woody riparian area have been found but many of the cases are associated with change in river regime (Dixon & Johnson, 1999;Johnson, 1994;Perona, Molnar, Savina, & Burlando, 2009), especially due to dam control (Dixon, Johnson, Scott, Bowen, & Rabbe, 2012;Gonzalez et al, 2010;Merritt & Cooper, 2000). Other causes of change such as land-use management impacts have been investigated or demonstrated (Sawtschuk, Delisle, Mesmin, & Bernez, 2014), as well as climatic and natural hydrologic variations (e.g.…”

Dismantling artificial levees and channel revetments promotes channel widening and regeneration of riparian vegetation over long river segments

“…In degraded floodplains constrained by human activities, the regeneration of riparian vegetation is limited to narrow, unprotected areas running parallel to a main channel that no longer migrates (Cordes et al, 1997;Dixon et al, 2012;Martinez-Fernandez et al, 2017). In these cases, the removal and setback of artificial levees and rip-rap channel revetments to re-activate channel migration, generally referred in this paper to as longitudinal structures manipulation, have been suggested as the most effective strategies for restoring endangered riparian plant communities (Biron et al, 2014;Gonzalez et al, 2010;Gothe et al, 2016;Scott et al, 1996).…”