Non-indigenous plant species and their ecological range in Central European pine (Pinus sylvestrisL.) forests

Abstract

-In this study, forest ecosystems were analysed with regard to the occurrence and ecological range of non-indigenous plant species. Pine forests in the NE German lowland, which naturally and anthropogenically occur on a broad range of different sites, were taken as an example. The analysis is based on a data set of about 2 300 vegetation plots. The ecological range was assessed applying Ellenberg's ecological indicator values. Out of a total of 362 taxa recorded in the pine forests, only 12 non-indigenous species, including trees, shrubs, annual and perennial herbs, and one bryophyte were found. They commonly grow on sites with relatively high nitrogen availability and soil reaction values. Most species are native to North America. Taking into account that a high proportion of the investigated pine forests is of anthropogenic origin and will naturally develop towards broad-leaved forests with beech and oak, it is hypothesised that most of the observed invasions are reversible.

Interaction between invasive and potentially invasive shrub species does not influence relationships between their ecological success and distance from propagule sources

“…Together with higher frequency in coniferous tree stands (27/95 vs. 6/56), this may show that C. alternifolia occurs in coniferous tree stands rather than in broadleaved stands, similar to P. serotina . It also confirms observations of Zerbe and Wirth (2006), which found that tree stands of Pinus sylvestris host numerous alien species, including many invasive species. This case may also be considered as an invasional meltdownplantations of ecologically (and mostly also geographically) alien coniferous species facilitate dispersal distance of secondary invaders-P. serotina and C. alternifolia, and both species invade the most invasible stands.…”

“…Introduction of coniferous species, which are ecologically alien (according to potential natural vegetation) and in most cases geographically alien, is also an introduction of alien species, which resulted in changes of ecosystem properties (transformers sensu Richardson et al 2000). Although we did not measure this transformation, there are a lot of studies describing how coniferous trees planted in habitats of broadleaved forests affect light conditions (e.g., Knight et al 2008;Niinemets 2010;Mueller et al 2016) or soil chemistry (e.g., Binkley and Valentine 1991;Reich et al 2005;Mueller et al 2012), which generally facilitated invasion of alien species (Obidziński and Symonides 2000;Chmura 2004Chmura , 2014Zerbe and Wirth 2006;Paritsis and Aizen 2008). Both species studied coexist in the arboretum, similar to their native range (Burns and Honkala 1990;Coladonato 1994).…”

“…Modifying effects of invasive woody species on habitat was also reported from several biomes across the world (e.g., Vitousek 1990; Ehrenfeld 2003;Stohlgren and Rejmánek 2014;Castro-Díez et al 2014;Menge and Chazdon 2016). Among woody species, some guilds are especially responsible for ecosystem change, e.g., nitrogenfixing species (e.g., Ehrenfeld 2003; Rice et al 2004;Castro-Díez et al 2014;Jo et al 2015) or coniferous trees planted on sites typical to broadleaved trees (e.g., Binkley and Valentine 1991;Augusto et al 2002;Zerbe and Wirth 2006;Jagodziński et al 2015).…”

“…Propagule pressure is also connected with the presence of dispersal agents, in the case of species producing edible fruits, with presence of frugivorous birds. Behavior of dispersal agents may influence spread of some species-for example presence of coniferous tree stands as places for perching and defecation ( _ Zywiec et al 2013). …”

Patterns of plant invasions at small spatial scale correspond with that at the whole country scale

“…Impatiens parviflora is a widely-dispersed therophyte, which is able to invade most forest plant communities (Tokarska-Guzik 2005; Zerbe and Wirth 2006;Chmura 2014). In the study area, I. parviflora occurred in all types of forest plant communities (Ratyńska, 2001;Dyderski and Jagodziński 2014;Dyderski and Wrońska-Pilarek 2015), being a frequent and persistent understory element.…”