Some features of invasive plants stipulating active spread within last decades

Abstract

Biological invasions are among the greatest threats to biodiversity of natural ecosystems. The majority of alien plant species were intensively spreading at the end of 19th and beginning of the 20th century. Most of invasive species of temperate climate zone are escapers from the warmer regions of the world. Due to ongoing climate change alien species are extending their invasive range of distribution towards more northern areas. Climate warming also has an impact to ecosystems leading to invasion process intensification. One of nowadays flourishing alien species in more southern Baltic States is wild cucumber (Echinocystis lobata (Michx.) Torr. et A. Gray). It is an annual vine, native in North America, brought to Europe as ornamental and medicinal plant which later escaped from cultivation and became invasive. According to Ellenberg indicatory values of plants in Central Europe, wild cucumber is highly thermophilic species. When rainfall is high enough, rise of ambient temperatures which are less than optimal for plant growth might have the positive impact to the plant development. Within decades of ongoing millennium wild cucumber has intensively spread along river banks of Lithuania. Such fact coincides with the 2011-2015 climate data assuming these years as the warmest period. For this interval annual mean temperature of Lithuania was 7.7 °C and mean temperature of vegetation period 13.3 °C. Therefore the aim of this study was to evaluate patterns of the plant dynamics. Study was funded by Lithuanian Research Council, Grant number No. SIT-02/2015. Wild cucumber was sampled in ruderal places and riverbanks. Morphological and gravimetric parameters highlighted huge potential of aboveground expansion for this species. Gravimetric and morphometric parameters per individual were much higher compared to what we may expect from the literature: maximum morphological parameters observed were as follows: [...]