Bryophyte community assembly on young land uplift islands – Dispersal and habitat filtering assessed using species traits

Abstract

Aim To assess habitat filtering and dispersal limitation in spore plant community assembly using bryophytes on recently emerged land uplift islands as study system. Location Gulf of Bothnia, northern Europe. Taxa Bryophytes, including the spore plant phyla Bryophyta (mosses) and Marchantiophyta (liverworts). Methods The species compositions of 20 coastal land uplift islands differing in age, area, connectivity and habitat composition were recorded in the field. In addition, we compiled a list of the regional species pool (446 species) and gathered data on species traits related to habitat affiliations (substrate, light, moisture, and pH) and dispersal capacity (regional abundance, spore size, sporophyte frequency, sexual system, vegetative propagules). For the 420 species with available trait data, we used multivariate generalized linear models to compare trait effects on species occurrence probabilities on the islands. Results Occurrence probabilities depended strongly on habitat affiliations. In addition, occurrence probabilities were lower for predominantly asexual species than for sexual species and for regionally rare than for regionally abundant species. Having specialized asexual propagules increased occurrence probabilities, but compensated only partly for the reductions in asexual species. No effect of the size of sexually produced spores was detected. Comparison of trait effects across island size and connectivity gradients revealed (a) reduced habitat filtering on larger islands and (b) decreasing negative effects of being predominantly asexual with increasing island connectivity. Conclusions Both habitat filtering and dispersal capacities affect the community assembly of spore plants on land uplift islands. Asexual mosses and liverworts show landscape scale (≤10 km) dispersal limitation. The weak or absent relationships between island connectivity and the effects of dispersal traits suggest that colonization is regulated mainly by habitat availability and the abundance of each species in a “regional spore rain” from which colonists are recruited.

Rapid post‐fire re‐assembly of species‐rich bryophyte communities in Afroalpine heathlands

“…A large proportion of the species observed in our study are fertile and produced sporophytes. The frequency of sporophytes is shown to be more important than for example terminal velocity (determined by spore size) in explaining colonization frequency in some systems (Lönnell & Hylander, 2018;Karlsson Tiselius et al, 2019). Studies show that spore-dispersed organisms can colonize sites hundreds or thousands of kilometres away if there is enough time (i.e.…”

Similar mechanisms underlie beta diversity of bryophytes in two archipelagos with different isolation time

“…The emergence of these inconsistent results is likely related to the species dispersal ability. Isolation is not the main factor limiting bryophytes’ distribution, but it has been noticed that the presence of bryophyte species is likely to depend on substrate availability, habitat quality, and habitat heterogeneity (Márialigeti et al 2009, Mota de Oliveira et al 2009, Tiselius et al 2019). For example, varied habitat quality among host types would increase dissimilarities among bryophyte communities (Kraichak 2014), and numerous studies have found that community composition (of epiphytic bryophytes) was mainly regulated by habitat heterogeneity (Pharo and Zartman 2007, Kraichak 2014, Mota de Oliveira and ter Steege 2015).…”

“…Relationships of observed beta diversity (Bray-Curtis dissimilarity) as a function of the difference in island area (a) and isolation (b) in Thousand Island Lake (TIL; red circles) and Zhoushan (ZS; blue squares) archipelago. Best-fit lines from multiple regression on distance matrices are shown in each panel: (a) TILR 2 = 0.139, P = 0.006; ZSR 2 = 0.132,P = 0.003; (b) TILR 2 = 0.003,P = 0.709; ZSR 2 = 0.001,P = 0.791. and habitat heterogeneity (M arialigeti et al 2009, Mota de Oliveira et al 2009, Tiselius et al 2019. For example, varied habitat quality among host types would increase dissimilarities among bryophyte communities (Kraichak 2014), and numerous studies have found that community composition (of epiphytic bryophytes) was mainly regulated by habitat heterogeneity Zartman 2007, Kraichak 2014, Mota de Oliveira and ter Steege 2015).…”

“…Understanding mechanisms of community assembly on islands has long been of interest to researchers, who frequently find that dispersal limitation and/or habitat heterogeneity shape community assembly in fragmented systems (e.g., Ernest et al 2008, Rominger et al 2016, Liu et al 2018, 2020). However, most such studies in fragmented landscapes focus on the assembly mechanisms of woody or herbaceous plants (e.g., Burns et al 2010, Keppel et al 2010, Carvajal‐Endara et al 2017), and we know little about other organisms, such as bryophytes (but see Tiselius et al 2019), which are broadly distributed (Hedenäs 2007, Frahm 2008) and play important functional roles in terrestrial ecosystems (Lindo and Gonzalez 2010, Deane‐Coe and Stanton 2017). As bryophytes require specific microhabitats, establish on spatially discrete habitats rapidly (Zartman 2003), and have strong dispersal ability due to their small unicellular spores (Hutsemekers et al 2008, Vanderpoorten et al 2019), they can give us the opportunity to examine the role of habitat heterogeneity and dispersal limitation in community assembly processes.…”

500 million years of charted territory: functional ecological traits in bryophytes

“…These traits shape species distributions and community structure (e.g. Patiño et al 2013, Löbel et al 2018, Tiselius et al 2019. For example, Sierra et al (2019) have shown that propagule characteristics predict succession in high diversity tropical epiphyll community.…”