Long‐term Vegetation Dynamics After High‐density Seedling Establishment: Implications for Riparian Restoration and Management

Abstract

Human disturbances have contributed to the deterioration of many western US rivers in the past century. Cottonwood-willow communities, present historically along the Colorado River, protect watersheds and provide wildlife habitat, but are now among the most threatened forests. As a result, restoration efforts have increased to re-establish and maintain cottonwood-willow stands. While successful establishment has been observed using multiple strategies with varying investments, few projects are evaluated to quantify efficacy and determine long-term sustainability. We monitored a seeded cottonwood-willow site over a five-year period beginning in 2007, with particular interest in how density affected vegetation diversity and stand structure over time. Fremont cottonwood (Populus fremontii) and volunteer tamarisk (Tamarix ramosissma) were the only abundant riparian trees at the site after one year. P. fremontii, compared to T. ramosissma, had higher growth rates, lower mortality, and dominated overstory and total cover each year. Vegetation diversity decreased from 2007-2009, but was similar from 2009-2011 as a result of decreased herbaceous and increased shrub species richness. Diversity was highest in the lowest density class (1-12 stems/m 2 ), but similar among all other classes (13-24, 25-42, 43+). High initial woody species densities resulted in single-stemmed trees with depressed terminal and radial growths. Allometry, relating height to DBH at different densities, could prove to be an important tool for long-term restoration management and studying habitat suitability. Understanding long-term trends at densely-planted or seeded sites can benefit restoration managers who aim to establish specific community structure and vegetation diversity for wildlife habitat.

“The rich get richer” concept in riparian woody species – A case study of the Warta River Valley (Poznań, Poland)

“…There are species which constitute an extraordinary threat for native vegetation of river valleys, such as Elaeagnus angustifolia and Tamarix spp. in the USA (Cooper et al, 2003;Friedman et al, 2005;Jarnevich and Reynolds, 2011;Bunting et al, 2013) or Acer negundo in the European temperate zone (Saccone et al, 2010(Saccone et al, , 2013Lamarque et al, 2012).…”

Determining Characteristic Vegetation Areas by Terrestrial Laser Scanning for Floodplain Flow Modeling

“…Generally, flow-vegetation interactions affect sediment and solute transport, channel morphology, and habitat quality. In environmentally sensitive engineering practices, vegetation is used for riverbank stabilization, increasing biodiversity, and forming riparian buffer zones, where the monitoring of vegetation structure and diversity is essential for improving future practices [6]. For the monitoring and modeling of riverine environments and floodplain flows, vegetation characteristics describing the structure and distribution of vegetation are needed.…”

Large herbivores as a driving force of woodland-grassland cycles : the mutual interactions between the population dynamics of large herbivores and vegetation development in a eutrophic wetland

“…In the past few centuries, the large natural rivers and floodplains have dramatically changed through embankments, canalizations, dams, weirs, groynes, and reclamation of the floodplain for agriculture (e.g. Dynesius and Nilsson 1994;Rosenberg et al 2000;Tockner and Stanford 2002;Bunting et al 2013). As a consequence, natural floodplains have become endangered landscapes, and many riverine habitat types such as floodplain forest have become rare (e.g.…”

“…As a consequence, natural floodplains have become endangered landscapes, and many riverine habitat types such as floodplain forest have become rare (e.g. Dynesius and Nilsson 1994;Brown et al 1997;Olson and Dinerstein 1998;Tockner and Stanford 2002;Bunting et al 2013). Restoration and conservation of these floodplain forests have become an important goal in river management (e.g.…”

“…Restoration and conservation of these floodplain forests have become an important goal in river management (e.g. Brown et al 1997;Leyer et al 2012;Bunting et al 2013). …”