Calcicolous plants colonize limed mires after long‐distance dispersal

Abstract

Aim Dispersal range is a key factor for understanding species' persistence in dynamic landscapes. However, dispersal, especially over long distances, is inherently difficult to study. Making use of a unique system of anthropogenically disturbed, geographically isolated mires, we assessed dispersal ranges for a group of plants restricted to wet calcareous conditions via empirical studies of colonization patterns. We hypothesized that more species would have colonized the less isolated mires and that colonization frequencies would be related to traits influencing propagule pressure. Location Sweden. Taxon Calcicolous vascular plants and bryophytes. Methods The study system consisted of 52 acidic mires that had acquired a high pH through active liming by the Swedish government during the past two decades. These conditions killed off mat‐forming peat mosses, rendering the mires open to colonization by other species. In each mire, we recorded the presence of rich fen plant species typically found in high pH wet soils throughout the country. We used citizen science‐collected records of occurrences of obligate‐rich fen species surrounding each mire to examine the likely dispersal distances that were involved in creating the colonization patterns. Results A lower proportion of vascular plants than bryophytes from their respective species pools colonized the limed mires (27% vs. 67%, p = .001). The number of colonized rich fen species per site was 0–6 for vascular plants and 10–31 for bryophytes, and was positively related to potential diaspore sources >20 km from the mires (p = .026 and p = .012, respectively). The proportion of colonized mires was positively related to the species' regional frequency, but not with their diaspores' terminal velocity. Main conclusions Many bryophyte species can effectively disperse over long distances (tens of kilometres) and variation among species in total diaspore production seems to be an important regulator of colonization across landscapes, for both vascular plants and bryophytes, in communities that are open to colonization.

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

“…In our results, this abundance effect is indicated by the strong negative effect on occurrence probability of being regionally non‐abundant (Figures c and b). Paralleling our findings, Lönnell and Hylander () found a high dependence on the regional spore output for the colonization probability of calcicolous bryophytes in limed acidic mires. The probability of a species colonizing at least one limed mire was dependent on both the sporophyte production frequency and the regional occurrence frequency of the species.…”

Genetic variation and reproductive patterns in wetland mosses suggest efficient initial colonization of disturbed sites

“…Scorpidium cossonii spores that colonize the unoccupied limed fens represent the overall genetic variation in the spore rain of the study region, and the sampled shoots represent this spore rain after chance effects and environmental filtering during establishment. This agrees with the generally excellent dispersal abilities of bryophytes (Lönnell & Hylander, 2018, Lönnell et al, 2012, Zanatta et al, 2016but see Löbel et al, 2006, Virtanen & Oksanen, 2007. The early-successional stage sites are alike in their genetic makeup and in the overall balanced sex ratios, due to the homogeneous spore rain and their similar recent history and environmental settings.…”

“…Fieldwork was conducted, and plant material of S. cossonii and C. stellatum was sampled, in limed mires (Lönnell and Hylander (2018) and in natural rich fens (N. Lönnell, unpublished data) in Central to Northern Sweden during July-September 2012. At each study site with an ample cover of both or at least one of the study species, the species were sampled from a central 50 × 50 m square in limed fens, or from a corresponding or slightly larger central area in natural rich fens, respectively (Lönnell & Hylander, 2018). At each site, we collected five samples, that is, patches of the study species of ca.…”

“…It is difficult to find natural systems to study colonization patterns at the landscape scale, the prime example being newly formed volcanic islands (Karadimou et al, 2018 ; Magnússon et al, 2014 ). However, Lönnell and Hylander ( 2018 ) showed that a unique system of acidic mires that were recently disturbed by regular liming, and that therefore attained a totally different chemical edaphic condition, was perfectly suited to examine colonization processes of vascular plants and bryophytes over large geographic areas. A limed acidic mire is, at least temporarily, transferred into a habitat that in many respects, such as water chemistry and wetness (Löfgren, 2007 ), resembles a natural rich fen in an early succession stage.…”

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.…”