Latitudinal variation in soil nematode communities under climate warming-related range-expanding and native plants.

Current climate change has led to latitudinal and altitudinal range expansions of numerous species. During such range expansions, plant species are expected to experience changes in interactions with other organisms, especially with belowground biota that have a limited dispersal capacity. Nematodes form a key component of the belowground food web as they include bacterivores, fungivores, omnivores and root herbivores. However, their community composition under climate change-driven intracontinental range-expanding plants has been studied almost exclusively under controlled conditions, whereas little is known about actual patterns in the field. Here, we use novel molecular sequencing techniques combined with morphological quantification in order to examine nematode communities in the rhizospheres of four range-expanding and four congeneric native species along a 2,000 km latitudinal transect from South-Eastern to North-Western Europe. We tested the hypotheses that latitudinal shifts in nematode community composition are stronger in range-expanding plant species than in congeneric natives and that in their new range, range-expanding plant species accumulate fewest root-feeding nematodes. Our results show latitudinal variation in nematode community composition of both range expanders and native plant species, while operational taxonomic unit richness remained the same across ranges. Therefore, range-expanding plant species face different nematode communities at higher latitudes, but this is also the case for widespread native plant species. Only one of the four range-expanding plant species showed a stronger shift in nematode community composition than its congeneric native and accumulated fewer root-feeding nematodes in its new range. We conclude that variation in nematode community composition with increasing latitude occurs for both range-expanding and native plant species and that some range-expanding plant species may become released from root-feeding nematodes in the new range.

Chemotype diversity of indigenous Dalmatian sage (Salvia officinalis L.) populations in Montenegro.

To identify how many chemotypes of Salvia officinalis exist in Montenegro, the chemical composition of the essential oils of 12 wild-growing populations was determined by GC-FID and GC/MS analyses. Among the 40 identified constituents, the most abundant were cis-thujone (16.98-40.35%), camphor (12.75-35.37%), 1,8-cineol (6.40-12.06%), trans-thujone (1.5-10.35%), camphene (2.26-9.97%), borneol (0.97-8.81%), viridiflorol (3.46-7.8%), limonene (1.8-6.47%), α-pinene (1.59-5.46%), and α-humulene (1.77-5.02%). The composition of the essential oils under study did not meet the ISO 9909 requirements, while the oils of populations P02-P04, P09, and P10 complied with the German Drug Codex. A few of the main essential-oil constituents appeared to be highly intercorrelated. Strong positive correlations were observed between α-pinene and camphene, camphene and camphor, as well as between cis-thujone and trans-thujone. Strong negative correlations were evidenced between cis-thujone and α-pinene, cis-thujone and champhene, cis-thujone and camphor, as well as between trans-thujone and camphene. Multivariate analyses allowed the grouping of the populations into three distinct chemotypes, i.e., Chemotype A, rich in total thujones, Chemotype B, with intermediate contents of thujones, α-pinene, camphene, and camphor and high borneol contents, and Chemotype C, rich in camphor, camphene, and α-pinene. The chemotypes did not significantly differ in the total essential-oil content and the cis/trans-thujone ratio.

Range-expansion effects on the belowground plant microbiome.

Plant range expansion is occurring at a rapid pace, largely in response to human-induced climate warming. Although the movement of plants along latitudinal and altitudinal gradients is well-documented, effects on belowground microbial communities remain largely unknown. Furthermore, for range expansion, not all plant species are equal: in a new range, the relatedness between range-expanding plant species and native flora can influence plant-microorganism interactions. Here we use a latitudinal gradient spanning 3,000 km across Europe to examine bacterial and fungal communities in the rhizosphere and surrounding soils of range-expanding plant species. We selected range-expanding plants with and without congeneric native species in the new range and, as a control, the congeneric native species, totalling 382 plant individuals collected across Europe. In general, the status of a plant as a range-expanding plant was a weak predictor of the composition of bacterial and fungal communities. However, microbial communities of range-expanding plant species became more similar to each other further from their original range. Range-expanding plants that were unrelated to the native community also experienced a decrease in the ratio of plant pathogens to symbionts, giving weak support to the enemy release hypothesis. Even at a continental scale, the effects of plant range expansion on the belowground microbiome are detectable, although changes to specific taxa remain difficult to decipher.

Beach litter along various sand dune habitats in the southern Adriatic (E Mediterranean).

Marine litter accumulates on sandy beaches and is an important environmental problem, as well as a threat to habitat types that are among the most endangered according to EU legislation. We sampled 120 random plots (2 × 2 m) in spring 2017 to determine the distribution pattern of beach litter along the zonation of habitat types from sea to the inland. The most frequent litter items were plastic, polystyrene and glass. A clear increase of litter cover along the sea-inland gradient is evident, and foredunes and pine forests have the highest cover of litter. Almost no litter was present in humid dune slacks. Shoreline and recreational activities are the major source of beach litter, while ocean/waterway activities are more important in the aphytic zone and strandline.