The influence of the groundlayer structure on the invasion of small balsam (Impatiens parviflora DC.) to natural and degraded forests

Abstract

<em>Impatiens parviflora</em> DC. was brought to European botanic gardens in 1837, from which it escaped and spread over almost the entire continent colonising predominantly synanthropic habitats. However, in the second half of the 20th century it also became permanently naturalised in natural deciduous forests. The causes of small balsam's success in colonisation of new habitats are not known. They may include either the continuous degradation of forest phytocoenoses or those properties of the alien species that allow it to colonise degraded habitats more effectively as compared to the native species. The aim of this paper was to verify the hypothesis on the relationship between the floristic and structural degradation of the herbaceous or groundlayer and its resistance to the invasion of <em>I. parviflora</em>. The investigations were carried out in the Forest Reserve "Las Bielański" in Warsaw using 30 transects that crossed natural floodplain forests and natural and degraded lime-hornbeam forests. The study has shown that: (1)there is a significant negative correlation between the species richness and cover of the groundlayer and the frequency, cover, and density of the population of <em>I. parviflora</em>; (2) small balsam easily penetrates into degraded and floristically impoverished communities; (3) dense groundlayer of the natural communities provides an effective barrier to the expansion of <em>I. parviflora</em>. This expansion is promoted by such disturbances of the groundlayer that induce formation of gaps providing safe microsites for seed germination and further growth of seedlings

Ecological lands for conservation of vascular plant diversity in the urban environment

“…The easiest is creating nature reserves -a regime with relatively small areas with high level of restrictions on visitation and use by the public. This form of nature conservation is used, for example, in Prague (Jarošík et al 2011a;Jarošík et al 2011b), Warsaw (Solińska-Górnicka and Symonides 1990; Obidziński and Symonides 2000), Budapest (Samu and Szinetár 2000) and in peri-urban areas of Zurich (Seeland et al 2002). However, there is difficulty in creating traditional, high-restrictive forms of nature conservation in highly-populated urban areas, where recreational areas are needed (Niemelä 1999;Seeland et al 2002;Jaszczak and Wajchman 2014).…”

Does Protection Really Matter? A Case Study from Central European Oak Forests

“…However, the most important factor responsible for the changes in species composition seems to be invasion of neophytes. The issue of the rapid invasion of Impatiens parviflora into PAs of Central Europe was raised among others by Pyšek et al [15], Obidziński & Symonides [45], Chmura & Sierka [46] and Łysik [47]. Impatiens parviflora is also often found in studied oak forests, constituting the most common of the listed neophytes.…”

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

“…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).…”