Traits of Heracleum sosnowskyi Plants in Monostand on Invaded Area

Abstract

The ability of giant hogweeds to form monodominant communities and even pure monostands in invaded areas has been well documented. Understanding of the mechanisms leading to monostand formation can aid in determining the limitations of existing community ecology models and establishing an effective management plan for invasive species elimination. The aim of this observational study was to investigate traits of Heracleum sosnowskyi plants (demography, canopy structure, morphology and physiology) of the plants in a pure stand in an invaded area useful for understanding potential monostand formation mechanisms. All measurements were performed in one typical Heracleum sosnowskyi monostand located in an abandoned agriculture field located in Syktyvkar city suburb (North-east Russia). This monostand consisted of five main plant growth stages: seed, seedling, juvenile, vegetative adult, and generative adult. Plants of all stages began to grow simultaneously shortly after the snowmelt, at the same time as spring ephemeral plant species grew. The density of generative plants did not change during the vegetation period, but the density of the other plant stages rapidly decreased after the formation of a tall (up to 2–2.5 m) and dense (Leaf area index up to 6.5) canopy. The canopy captured approximately 97% of the light. H. sosnowskyi showed high (several orders of magnitude higher than average taiga zone grasses) photosynthetic water use efficiency (6–7 μM CO2/μM H2O). Formation of H. sosnowskyi monostands occurs primarily in disturbed areas with relatively rich and well-moistened soils. Early commencement of growth, rapid formation of a dense canopy, high efficiency of light and water use during photosynthesis, ability of young plants to survive in low light conditions, rapid recovery of above-ground plant parts after damage, and the high density of the soil seed bank are the most important traits of H. sosnowskyi plants for monostand formation in invaded areas.

How does an invasive Heracleum sosnowskyi affect soil nematode communities in natural conditions?

“…This applies in particular to the Pp 3 functional guild nematodes (Geocenamus, Helicotylenchus, Pratylenchus and Tylenchorhynchus), which clearly confirms our earlier findings from the H. sosnowskyi-invaded habitats in Lithuania (Renčo & Baležentiené, 2015). This is probably caused partially by modification in undergrowth vegetation and root depletion in all habitats where H. sosnowskyi be-comes prevalent, due to strong shading and allelopathic impact (Kabuce & Priede, 2010;Dalke et al, 2015). Additionally, Heracleum spp.…”

“…Heracleum sosnowskyi is a biennial or perennial plant that has the ability to form pure monostands in invaded areas (Kabuce & Priede, 2010;Baležentienė & Bartkevičius, 2013;Dalke et al, 2015). Heracleum sosnowskyi grew in all the investigated habitats but in the 'wet-dump ground depression' it did not expand to become the dominant species (Table 1).…”

Seed Viability of Heracleum mantegazzianum (Apiaceae) Is Quickly Reduced at Temperatures Prevailing in Biogas Plants

“…Heracleum mantegazzianum Sommier & Levier, giant hogweed, is one of the most successful invader weed species in Europe [1], causing biodiversity loss and reduced ecosystem functioning [2][3][4]. Due to its rapid, competitive growth and reproduction potential giant hogweed species have a high potential for further infestation and strong survival [5][6][7]. Preserving biodiversity is part of the Convention on Biodiversity, particularly with regard to taking precautions against alien species and, if necessary, controlling them [8].…”

The impact of Sosnowsky’s Hogweed on feeding guilds of birds

“…Second, based on reproductive potential studied on different invasive Caucasian hogweeds, one plant may produce 5-50 thousand seeds per year (Orlov et al 1990;Perglová et al 2007), which can germinate for 5-6 years (Orlov et al 1990). These seeds are extremely abundant in upper soil layers (Moravcová et al 2007;Dalke et al 2015) and easily accessible for granivorous and omnivorous birds (although it was not studied whether birds use those seeds). On the other hand, it can also lead to habitat monopolization and impoverishment of the environment potentially used by foraging birds.…”