Does tree seedling growth and survival require weeding of Himalayan balsam (Impatiens glandulifera)?

Abstract

The effect of Himalayan balsam (Impatiens glandulifera) on survival and growth of naturally regenerated silver birch (Betula pendula) and planted Norway spruce (Picea abies) and silver fir (Abies alba) seedlings was studied in a weeding experiment over 3 years. Three different treatments were applied: control, mowing, and hand weeding by pulling out the entire plant. There were no consistent treatment effects on height and diameter of the tree seedlings. The coverage of Rubus fruticosus had a negative impact on diameter increment of Norway spruce and silver fir. As opposed to growth, treatment effects on seedling survival could be found for planted Norway spruce and silver fir. However, it is very likely that these effects, namely higher seedling survival after mowing, have to be attributed to the control of bramble (Rubus fruticosus) rather than to that of Himalayan balsam. It is concluded that Himalayan balsam is not able to seriously affect the growth of already established seedlings.

The invasive Impatiens glandulifera Royle (Himalayan balsam) in the Republic of Macedonia: first record and forecast

“…However, Maule et al (2000) showed that in the UK I. glandulifera could successfully compete with native plants, including tree seedlings with the potential to inhibit the regeneration cycle of woodlands. This was not the case, in Germany, Ammer et al (2011), found no impact of I. glandulifera on established tree seedlings.…”

“…This was not the case, in Germany, Ammer et al . (), found no impact of I. glandulifera on established tree seedlings.…”

Species- and developmental stage-specific effects of allelopathy and competition of invasive Impatiens glandulifera on co-occurring plants

“…In contrast, other studies did not find such negative effects. Thus, seed germination [ 33 ], and forest recruitment were not restricted in invaded forest sites [ 34 ]. These varied outcomes may be caused by context-dependencies, because all these studies were conducted with different settings regarding study conditions, target plants, their developmental stages and the parts of I .…”

Wasserkraft und Nachhaltigkeit

“…Dennoch wird in der aktuellen Forschung parallel dazu diskutiert, ob die Bedeutung von Impatiens glandulifera Royle nicht überschätzt wird. So wird beispielsweise argumentiert, dass das Indische Springkraut lediglich eine freie ökologische Nische innerhalb der Auenbestände besetzen würde oder maximal in Konkurrenz zu anderen dominanten Nitrophyten wie der Großen Brennnessel (Urtica dioica) treten würde (Ammer et al, 2011;Hejda & Pyšek, 2006;Hejda et al, 2009;Kowarik, 2003).…”