Soil Seed Bank of Alien and Native Cornus (Cornaceae) Taxa in Lithuania: What Determines Seed Density and Vertical Distribution in Soil?

Abstract

Soil seed banks of alien plant species are sources of propagules that play a crucial role in plant population dynamics. Studies on seed banks of woody alien species are crucial for understanding mechanisms of their encroachment on natural habitats. This study aimed to compare vertical distribution, density and composition of seed banks formed by native Cornus sanguinea subsp. sanguinea and alien C. alba, C. sericea and C. sanguinea subsp. australis in the Southern Hemiboreal zone of Europe. Five sites for each of four taxa were selected for the study, and seeds were sampled using the soil core method (400 samples in two soil layers: the upper, 0–5 cm, and the lower, 5–10 cm). Extracted seeds were tested with tetrazolium chloride stain to assess their viability. Differences in the seed banks among taxa were compared using generalised linear mixed models (GLMM). The GLMM analysis revealed significant differences in soil seed bank densities in the upper soil between the studied taxa (p < 0.001). We found that two of the alien taxa (C. alba and C. sanguinea subsp. australis) formed a much denser seed bank containing more viable seeds than the native Cornus sanguinea subsp. sanguinea. All three alien species contained more viable seeds (from 40.7% to 45.2% in the upper soil layer) than the native C. sanguinea subsp. sanguinea (19.4% in the upper and 18.2% in the lower soil layer). The cover of Cornus and habitat type had no significant effect on the density of the seed bank, according to GLMM. This study supports the hypothesis that seed banks of alien C. alba and C. sanguinea subsp. australis are denser than those of native C. sanguinea subsp. sanguinea. Furthermore, the seed bank of alien taxa contained more viable seeds than the seed bank of C. sanguinea subsp. sanguinea. Results of this study contribute to the understanding of the invasiveness of alien Cornus taxa.

Soil seed bank dynamics of two invasive alien plants in Nigeria: implications for ecosystem restoration

“…However, in this study, the highest number of seeds of H. suaveolens per m 2 is 161. This low density of seeds of the plant in this study could be attributed to the habitat conditions and stand characteristics ( Petrulaitis et al . 2022 ).…”

“…Plots of size 2 m × 2 m were used as sampling plots. At each site, soil samples were collected using soil cores made of steel frames (dimension: height = 10 cm, size = 10 × 10 cm 2 ) ( Petrulaitis et al . 2022 ).…”

“…The 600 dried soil subsamples (invaded and non-invaded sites inclusive) were hand-crushed, and the seeds were separated using different sets of sieves of sizes 3, 2, 1 and 0.25 mm ( Petrulaitis et al . 2022 ).…”

“…This was conducted on all the undamaged seeds obtained from the soil seed bank. The viability test was done using TTC test which has been recognized as a standard staining method ( Baskin and Baskin 1998 ; Petrulaitis et al . 2022 ).…”

“…We analysed the seed density by counting the number of seeds per subsample per study site. This gives us the mean seed density per unit square metre ( Petrulaitis et al . 2022 ).…”