No abstract

In this work, potential contamination by invasive plant propagules as a result of trade exchange between Slovakia and Romania, was assessed. National lists, describing biology and ecology of 30 worst invasive plant taxa, were formulated, and trading in period 2006-2010 between countries analysed. Using norms for commodity impurity level, information on species habitat occupancy and literature data dealing with seed/fruit attachment on roads we calculated then potential invasive plant propagule export (PE) for each taxon. We found three fold higher total good export from Slovakia than in opposite direction, increasing export of commodities potentially containing invasive plant propagules exported from Romania to Slovakia and rise of road compared to railway transport. PEs for Slovak invasive plant taxa were one-two orders higher than those for Romanian ones. Potentially most exported taxa for Slovakia were: Amaranthus sp., Ambrosia artemisiifolia, Galinsoga sp., Kochia scoparia and Sorghum halepense (tens to hundreds tonnes each). And these could mostly be exported from Romania: Amaranthus sp., Ambrosia artemisiifolia, Artemisia annua, Conyza canadensis, Cuscuta campestris, Datura stramonium, Erigeron annus, Galinsoga sp., Iva xanthiifolia, Kochia scoparia, Lycium barbarum, Sorghum halepense, Veronica persica and Xanthium orientale subsp. italicum (units to tens tonnes each). High PE was significantly associated with cereals export. Our formula for PE is applicable for any inter- and intra-continental trade exchange.

Ornamental plantations in cities and particularly botanical gardens and arboreta are rich sources of alien flora. Mlyňany Arboretum, established in 1892, cultivates 1049 non-native woody plant species on the area of 67 ha. In this work we answered following questions: 1. How many taxa are spontaneously spreading in the arboretum and how is the spreading intensity related to their ecological demands and reproduction traits? 2. How many taxa appear behind the fence? 3. How far from the arboretum they can get? 4. Do private gardens and historical aristocratic park in the studied village cluster contribute to species escapes from culture? 5. Which from the widely spread taxa can represent future risk of invasiveness on the national level? We found that about one tenth of taxa spread across the arboretum (particularly Cotoneaster spp., Prunus laurocerasus, P. serotina and Quercus rubra) and number of their seedlings corresponded only with the mother plant number. Almost one third of these species left the arboretum and their seedlings were observed in distance up to 500 m from the village (mainly Mahonia aquifolium, P. serotina). Private gardens were a large source of Juglans regia seedlings, frequency of which decreased with the distance from villages (no species escaped from the historical park). Weed risk assessment revealed potential invasion danger only for Amorpha fruticosa.

Diverse communities of bacterial endophytes inhabit plant tissues, and these bacteria play important roles for plant growth and health. Cherry laurel (Prunus laurocerasus L.) is a broadleaf evergreen shrub that is widely grown in temperate zones for its ornamental and medicinal properties, however virtually nothing is known about its associated bacterial community. In this study, we analysed the matured one-year-old leaves of this plant using Illumina-based 16S rRNA gene metabarcoding to reveal the community structure of endophytic bacteria and understand its shifts during the seasonal transition from winter dormancy to a spring vegetative state. The overall community was composed of four dominant phyla (Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes). Corynebacterium, Acinetobacter, and Chryseobacterium genera were the most prevalent bacteria, comprising 13.3%, 6.9%, and 6.8% of the amplicon sequence variants (ASVs), respectively. The ASV richness and diversity increased significantly in May as compared to other sampling months (February, March, and April). We observed high variation in the overall community structure of endophytic bacteria among collection dates. The variation was only reflected by a few core community members, suggesting that the changes of the endophytic community during winter/spring seasonal transition are mostly associated with the less abundant community members. We identified biomarker taxa for late winter, mid spring, and late spring collection dates. This study is the first one to report on the diversity and composition of bacterial endophytes in the leaves of cherry laurel and its shifts across the dormancy-to-vegetative seasonal transition.