Facilitation of afforestation byLupinus nootkatensisand by black plastic mulch in south-west Iceland

Abstract

Afforestation has proven difficult in south-west Iceland in a region of degraded soils and high winds. Experiments at Keflavik International Airport began in 2002 to examine whether Nootka lupine (lupin; Lupinus nootkatensis) or black plastic mulch facilitates establishment of Sitka spruce (Picea sitchensis), Hooker willow (Salix hookeriana) or downy birch (Betula pubescens) by ameliorating microsite conditions. By 2008, both lupine and black plastic mulch facilitated growth of all species at most plots. However, survival of spruce and birch seedlings decreased where dense lupine was accompanied by dense grass (but not in dense lupine alone). This indirect mechanism (nurse plant stimulation of competitor species) differs from prior models of shifts in balance from facilitation to competition under the stress-gradient hypothesis. Hooker willow performed best in both lupine and plastic mulch. However, in areas without dense grass, Sitka spruce continued successful growth and has potential for longer term afforestation. Planting seedlings into shallow excavations in lupine improved growth of willow and birch but not spruce. For afforestation in south-west Iceland, it is recommended that a mix of tree seedlings be transplanted directly into young lupine stands with sparse grass cover, with shelterbelts of seedlings planted into black plastic mulch along the stand edges.

Provenance variability in establishment of native downy birch in a 14-year trial in southwest Iceland

“…Jónsson (2004) found substantial differences from prostrate shrubs to trees in stature of downy birch in a study encompassing many stands throughout Iceland. The high degree of variation among downy birch provenances in Iceland may be the result of hybridization and gene flow from dwarf birch, Betula nana (Thórsson BIRCH PROVENANCE TRIAL Riege & Sigurgeirsson (2009) found that survival of birch seedlings, but not growth of the survivors, was greatly reduced with thick lupine, especially when accompanied by dense grass cover. Thus, it is recommended that lupine be seeded, rather than transplanted, at the same time as downy birch seedlings are planted.…”

“…The birch trial plot was established on rocky, eroded soil with patches of moss-heath cover dominated by Racomitrium moss, crowberry (Empetrum nigrum), and heather (Calluna vulgaris). More information about the site conditions at Reykjanes can be found in Riege & Sigurgeirsson (2009).…”

“…Recent advances in fertilization procedures were applied, since afforestation on barren land without fertilization usually yields high mortality and long periods of stagnant growth in Iceland (Óskarsson & Sigurgeirsson 2001, Óskarsson et al 2006, Óskarsson & Brynleifsdóttir 2009). Nootka lupine (Lupinus nootkatensis Sims) was transplanted into the trial five years after establishment, as a nearby study (Riege & Sigurgeirsson 2009) found that lupine facilitated growth of downy birch seedlings in this stressful environment. Lupine has been found to improve tree seedling establishment by nitrogen fixation, addition of organic material, and amelioration of microclimate (Myrold & Huss-Danell 2003, Mattson et al 2007).…”

“…It is an area of strong winds, eroded soils, salt spray, and little soil nitrogen (Riege & Sigurgeirsson 2009 (Aradóttir & Eysteinsson 2005), including an ambitious program (Hekluskógar) to reclaim ~1000 km 2 of tephra covered lands near Mt. Hekla (Aradóttir 2007).…”

State and Progress of Andean Lupin Cultivation in Europe: A Review

“…The fourth is the only representative from the 185 species of the "New World" group named L. mutabilis (Andean lupin, pearl lupin), called either tarwi or chocho bean, in regard to the tall species with long branches and the short plant growth type with few branches [10]. Three other lupins worth mentioning, although only of regional agricultural importance, are L. pilosus L., an Old World lupin used as a coffee substitute (Altreier Kaffee) in Northern Italy [11], L. nootkatensis D. ex S. (Nootka lupin), used for land reclamation [12][13][14] and L. polyphyllus Lindl. (Washington lupin), used as an ornamental in many European countries including Germany, Poland, Russia, Spain, Sweden, Ukraine and the United Kingdom.…”