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Humans as long-distance dispersers of rural plant communities
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
2013 (English)In: PLoS ONE, ISSN 1932-6203, Vol. 8, no 5, e62763- p.Article in journal (Refereed) Published
Abstract [en]

Humans are known for their capacity to disperse organisms long distances. Long-distance dispersal can be important for speciesthreatened by habitat destruction, but research into human-mediated dispersal is often focussed upon few and/or invasive species.Here we use citizen science to identify the capacity for humans to disperse seeds on their clothes and footwear from a knownspecies pool in a valuable habitat, allowing for an assessment of the fraction and types of species dispersed by humans in analternative context. We collected material from volunteers cutting 48 species-rich meadows throughout Sweden. We counted 24354 seeds of 197 species, representing 34% of the available species pool, including several rare and protected species. However, 71species (36%) are considered invasive elsewhere in the world. Trait analysis showed that seeds with hooks or other appendageswere more likely to be dispersed by humans, as well as those with a persistent seed bank. More activity in a meadow resulted inmore dispersal, both in terms of species and representation of the source communities. Average potential dispersal distances weremeasured at 13 km. We consider humans capable seed dispersers, transporting a significant proportion of the plant communities inwhich they are active, just like more traditional vectors such as livestock. When rural populations were larger, people might havebeen regular and effective seed dispersers, and the net rural-urban migration resulting in a reduction in humans in the landscapemay have exacerbated the dispersal failure evident in declining plant populations today. With the fragmentation of habitat andchanges in land use resulting from agricultural change, and the increased mobility of humans worldwide, the dispersal role ofhumans may have shifted from providers of regular local and landscape dispersal to providers of much rarer long-distance andregional dispersal, and international invasion.

Place, publisher, year, edition, pages
2013. Vol. 8, no 5, e62763- p.
National Category
Natural Sciences Engineering and Technology
URN: urn:nbn:se:su:diva-89134DOI: 10.1371/journal.pone.0062763ISI: 000321200500037OAI: diva2:615900
Available from: 2013-04-12 Created: 2013-04-12 Last updated: 2013-08-20Bibliographically approved
In thesis
1. Seed mobility and connectivity in changing rural landscapes
Open this publication in new window or tab >>Seed mobility and connectivity in changing rural landscapes
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The success or failure of many organisms to respond to the challenges of habitat destruction and a warming climate lies in the ability of plant species to disperse between isolated habitats or to migrate to new ranges. European semi-natural grasslands represent one of the world's most species-rich habitats at small scales, but agricultural intensification during the 20th century has meant that many plant species are left only on small fragments of former habitat. It is important that these plants can disperse, both for the maintenance of existing populations, and for the colonisation of target species to restored grasslands. This thesis investigates the ecological, geographical and historical influences on seed dispersal and connectivity in semi-natural grasslands, and the mobility of plants through time and space. Seed dispersal by human activity has played a large role in the build-up of plant communities in rural landscapes, but patterns have shifted. Livestock are the most traditional, and probably the most capable seed dispersal vector in the landscape, but other dispersal methods may also be effective. Motor vehicles disperse seeds with similar traits to those dispersed by livestock, while 39% of valuable grasslands in southern Sweden are connected by the road network. Humans are found to disperse around one-third of available grassland species, including several protected and red-listed species, indicating that humans may have been valuable seed dispersers in the past when rural populations were larger. Past activities can also affect seed mobility in time through the seed bank, as seeds of grassland plant species are shown to remain in the soil even after the grassland had been abandoned. Today however, low seed rain in intensively grazed semi-natural grasslands indicates that seed production may be a limiting factor in allowing seeds to be dispersed in space through the landscape.

Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography and Quaternary Geology, Stockholm University, 2013. 38 p.
Dissertations from the Department of Physical Geography and Quaternary Geology, ISSN 1653-7211 ; 37
Biodiversity, Conservation, Functional connectivity, Historical ecology, Human-mediated dispersal, Invasive species, Landscape Ecology, Long-distance dispersal, Restoration, Seed bank, Seed dispersal, Seed rain, Structural connectivity
National Category
Physical Geography Ecology
Research subject
Physical Geography
urn:nbn:se:su:diva-89105 (URN)978-91-7447-692-7 (ISBN)
Public defence
2013-06-05, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)
Formas, 2006-2130

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Accepted. Paper 4: In press. Paper 5: Manuscript.

Available from: 2013-05-14 Created: 2013-04-11 Last updated: 2013-05-03Bibliographically approved

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Auffret, Alistair G.Cousins, Sara
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