Quantifying the relationship between soil seed bank and plant community assemblage in sites harboring the threatened Ivesia webberi in the western Great Basin Desert

Abstract

Questions: The soil seed bank is an important ecosystem component that can be pivotal for long-term persistence of many plant species, especially after disturbances followed by the invasion of alien weeds. However, many Great Basin Desert perennials produce relatively few viable seeds, while large areas of the Great Basin are currently invaded by alien weeds. This could result in dissimilarity in floristic composition between the above-ground vegetative community and the soil seed bank, causing abrupt plant community shifts following disturbance. Therefore, we asked what is the relationship in the floristic composition between the above-ground communities and the soil seed bank in sites where the threatened Ivesia webberi occurs? Location: The Great Basin Desert, United States. Methods: We used Dice-Sorensen's similarity index to estimate similarity between the standing vegetation and the soil seed bank. Redundancy analysis and variation partitioning were used to quantify the relationship between the total abundance of the sampled above-ground flora and the soil seed bank, accounting for effects of spatial processes and environmental variables describing climate, soils, and vegetation in the 10 sites. Results: Findings reveal high dissimilarity in species assemblage and abundance between the above-ground plant communities and the soil seed bank. Most of the dominant native plant species sampled in the standing vegetation were absent in the soil seed bank, and the soil seed bank was dominated by invasive alien weeds. Conclusions: Divergence in the floristic composition between the above-ground communities and the soil seed bank in Ivesia webberi habitat indicates low resilience and high risk of native species loss following perturbation. Post-disturbance succession in these plant communities may be largely dominated by invasive annual species; therefore, reduction of invasive species and native plant seeding may be necessary to sustain the ecological legacies of the desert ecosystem.

Life in the desert: The impact of geographic and environmental gradients on genetic diversity and population structure of Ivesia webberi

“…This may explain field observations that suggest that the abundance of the invasive plant species does not prevent the annual vegetative regeneration of established matured I. webberi individuals. However, invasive alien species can hinder new recruitment of native plants by outcompeting the young and delicate seedlings (Borokini et al, 2021;Chambers et al, 2007).…”

“…Gamete dispersal (pollen) would result in pollination and hence admixture, whereas seed dispersal would not. Only through future Mantel tests were run in ECODIST R package, MRM analysis was conducted in phytools R package, both implemented with 10,000 permutations, while GDMs were fitted in the gdm R package with 1,000 permutations for the variable importance analysis a Species dissimilarity in both the aboveground vegetation and the soil seed bank were computed from 10 of the 16 I. webberi populations (Borokini et al, 2021). Therefore, pairwise genetic distance (F ST ) corresponding to the sampled 10 populations was used.…”

“…webberi individuals. However, invasive alien species can hinder new recruitment of native plants by outcompeting the young and delicate seedlings (Borokini et al, 2021; Chambers et al, 2007). Therefore, a significant relationship between beta diversity in the soil seed bank and the population genetic distance in the 10 surveyed sites may reflect effects of differing microhabitat conditions that affect seed‐based recruitment of I .…”

“…We tested the species-genetic diversity hypothesis, which posits that a relationship exists between I. webberi genetic diversity and the floristic dissimilarity across the sampled sites (Kahilainen et al, 2014;Whitlock, 2014). In a separate study (Borokini et al, 2021), species richness, abundance, and diversity of both the aboveground plant communities and the soil seed bank of 10 of the 16 sites were quantified (Appendix S5). Here, we conducted separate Spearman correlation tests between genetic diversity (i.e., allelic richness and mean observed heterozygosity), and floristic richness and diversity of both the aboveground vegetation and the soil seed bank in each of the 10 sites.…”

Spatial patterns of soil seed banks and their relationships with above‐ground vegetation in an arid desert

“…As for the relationship between SSB and above‐ground vegetation, much attention has been drawn to illustrate differences and similarities of species composition between these two communities by using statistical methods such as similarity index (Borokini et al, 2020), correlation coefficients and regression techniques (Tessema et al, 2017; Sanou et al, 2018). However, only a few studies concentrated on quantifying their spatial connections (Makarian et al, 2007).…”