The invasive effect of Solidago canadensis L. on the structural characteristics of soil nematode communities in the ecosystems of the eu-mesophytic meadows

Aim. To compare the eco-trophic structure of soil nematode communities in the ecosystems of the eu-mesophytic meadows in plots non-invaded and invaded by Solidago canadensis L. Methods. Soil samples from the rhizosphere of native meadow plants and those with S. canadensis were collected in September 2021 in two meadow ecosystems located on the outskirts of the villages Shostovytsia and Ladinka of the Chernihiv region. The nematodes were extracted by a modified Baermann's method from the 20 g samples. The exposure time was 48 h. The extracted nematodes were fixed in the triethanolamine–formalin (TAF, 2 % triethanolamine, 7 % formaldehyde solution, 91 % water), and mounted on the temporary hydroglyceric slides. The nematode abundance was expressed as specimens per 100 g of dry soil. The following parameters were analysed: abundance, taxonomic composition, dominance, trophic structure of soil nematode communities. The taxonomic wealth index, Menhinick's, Berger–Parker indexes, Jaccarda's index of similarity, and the maturity index were also calculated. Results. The average abundance of nematodes in the soil nematode communities was 1,075 individuals/100 g in the rhizosphere of native meadow plants and 636 individuals/100 g in the rhizosphere of S. canadensis. A total of 52 species were identified in the soil of meadow ecosystems: 44 — in the non-invaded plots and 29 — in the invaded plots; Menhinick's diversity index was 1.34 and 1.15, respectively. The taxonomic wealth index of nematode communities in the rhizosphere of native plants was also higher — ST = 116; in the rhizosphere of Canadian goldenrod — ST=84. Such families as Tylenchidae, Cephalobidae, Tylencholaimidae and Panagrolaimidae were more numerous in the soil samples of the native meadow plants (25 %, 18.4 %, 12.9 %, 10.3 % of the total number, respectively). Paratylenchidae, Tylenchidae, Cephalobidae and Aphelenchidae were more numerous in the plots with S. canadensis (37.1 %, 15.1 %, 14.3 %, 10.1 %, respectively). The taxonomic wealth index was higher in non-invaded plots (2.98) than those, invaded by Canadian goldenrod (2.75). The bacterivores and fungivores predominated quantitatively in nematode communities in the rhizosphere of native meadow plants. The proportion in the community amounted to 76.4 %. The plant parasites and fungivores were the most numerous in the plots with S. canadensis. The abundance of nematodes in other tropic groups were limited or not affected. Conclusions. It was determined that the species wealth and abundance, the taxonomic and trophic diversity of soil nematode communities were lower in the plots with the invasion by Canadian goldenrod. The abundance of plant parasites was higher (2.3 times); the ratio of fungivores to bacterivores was also higher in the invaded plots (1.2 times). The maturity index was lower in the invaded plots compared to the non-invaded ones (2.1 and 2.4) which demonstrates a more disturbed environmental conditions in the plots of the meadow with the invasion of the S. canadensis. The studies emphasize the need to monitor invasive species and develop strategies for their control in order to preserve soil biodiversity and support sustainable grassland management.